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	Author	Saniz, R.; Vercauteren, S.; Lamoen, D.; Partoens, B.; Barbiellini, B.
	Title	Accurate description of the van der Waals interaction of an electron-positron pair with the surface of a topological insulator			Type	P1 Proceeding
	Year	2014	Publication	Journal of physics : conference series	Abbreviated Journal
	Volume	505	Issue		Pages	012002
	Keywords	P1 Proceeding; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	Positrons can be trapped in localized states at the surface of a material, and thus quite selectively interact with core or valence surface electrons. Hence, advanced surface positron spectroscopy techniques can present the ideal tools to study a topological insulator, where surface states play a fundamental role. We analyze the problem of a positron at a TI surface, assuming that it is a weakly physisorbed positronium (Ps) atom. To determine if the surface of interest in a material can sustain such a physisorption, an accurate description of the underlying van der Waals (vdW) interaction is essential. We have developed a first-principles parameterfree method, based on the density functional theory, to extract key parameters determining the vdW interaction potential between a Ps atom and the surface of a given material. The method has been successfully applied to quartz and preliminary results on Bi2Te2Se indicate the existence of a positron surface state. We discuss the robustness of our predictions versus the most relevant approximations involved in our approach.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Bristol	Editor
	Language		Wos	000338216500002	Publication Date	2014-04-28
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1742-6588;1742-6596;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor		Times cited	2	Open Access
	Notes	; We thank A. Weiss for very useful conversations. We acknowledge financial support from FWO-Vlaanderen (projectG.0150.13). This work was carried out using the HPC infrastructure of the University of Antwerp (CalcUA), adivision of the Flemish Supercomputer Center (VSC), funded by the Hercules foundation and the Flemish Government (EWI Department). B. B. is supported by DOE grants Nos. DE-FG02-07ER46352 and DE-AC02-05CH11231 for theory support at ALS, Berkeley, and a NERSC computer time allocation. ;			Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:118264			Serial	46
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	Author	Dixit, H.; Tandon, N.; Cottenier, S.; Saniz, R.; Lamoen, D.; Partoens, B.; van Speybroeck, V.; Waroquier, M.
	Title	Electronic structure and band gap of zinc spinel oxides beyond LDA : ZnAl₂O₄, ZnGa₂O₄ and ZnIn₂O₄			Type	A1 Journal article
	Year	2011	Publication	New journal of physics	Abbreviated Journal	New J Phys
	Volume	13	Issue	6	Pages	063002-063002,11
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We examine the electronic structure of the family of ternary zinc spinel oxides ZnX2O4 (X=Al, Ga and In). The band gap of ZnAl2O4 calculated using density functional theory (DFT) is 4.25 eV and is overestimated compared with the experimental value of 3.83.9 eV. The DFT band gap of ZnGa2O4 is 2.82 eV and is underestimated compared with the experimental value of 4.45.0 eV. Since DFT typically underestimates the band gap in the oxide system, the experimental measurements for ZnAl2O4 probably require a correction. We use two first-principles techniques capable of describing accurately the excited states of semiconductors, namely the GW approximation and the modified BeckeJohnson (MBJ) potential approximation, to calculate the band gap of ZnX2O4. The GW and MBJ band gaps are in good agreement with each other. In the case of ZnAl2O4, the predicted band gap values are >6 eV, i.e. ~2 eV larger than the only reported experimental value. We expect future experimental work to confirm our results. Our calculations of the electron effective masses and the second band gap indicate that these compounds are very good candidates to act as transparent conducting host materials.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Bristol	Editor
	Language		Wos	000292137500002	Publication Date	2011-06-03
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1367-2630;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.786	Times cited	98	Open Access
	Notes	Iwt; Fwo; Bof-Noi			Approved	Most recent IF: 3.786; 2011 IF: 4.177
	Call Number	UA @ lucian @ c:irua:89555			Serial	1008
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	Author	Sarmadian, N.; Saniz, R.; Partoens, B.; Lamoen, D.; Volety, K.; Huyberechts, G.; Paul, J.
	Title	High throughput first-principles calculations of bixbyite oxides for TCO applications			Type	A1 Journal article
	Year	2014	Publication	Physical chemistry, chemical physics	Abbreviated Journal	Phys Chem Chem Phys
	Volume	16	Issue	33	Pages	17724-17733
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We present a high-throughput computing scheme based on density functional theory (DFT) to generate a class of oxides and screen them with the aim of identifying those that might be electronically appropriate for transparent conducting oxide (TCO) applications. The screening criteria used are a minimum band gap to ensure sufficient transparency, a band edge alignment consistent with easy n- or p-type dopability, and a minimum thermodynamic phase stability to be experimentally synthesizable. Following this scheme we screened 23 binary and 1518 ternary bixbyite oxides in order to identify promising candidates, which can then be a subject of an in-depth study. The results for the known TCOs are in good agreement with the reported data in the literature. We suggest a list of several new potential TCOs, including both n- and p-type compounds.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge	Editor
	Language		Wos	000341064800041	Publication Date	2014-07-07
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1463-9076;1463-9084;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.123	Times cited	23	Open Access
	Notes	; We gratefully acknowledge financial support from the IWT-Vlaanderen through the ISIMADE project (IWT-n 080023), the FWO-Vlaanderen through project G.0150.13 and a GOA fund from the University of Antwerp. This work was carried out using the HPC infrastructure of the University of Antwerp (CalcUA) a division of the Flemish Supercomputer Center VSC, which is funded by the Hercules foundation and the Flemish Government (EWI Department). ;			Approved	Most recent IF: 4.123; 2014 IF: 4.493
	Call Number	UA @ lucian @ c:irua:118263			Serial	1469
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	Author	Bekaert, J.; Saniz, R.; Partoens, B.; Lamoen, D.
	Title	Native point defects in CuIn_1-xGa_xSe₂ : hybrid density functional calculations predict the origin of p- and n-type conductivity			Type	A1 Journal article
	Year	2014	Publication	Physical chemistry, chemical physics	Abbreviated Journal	Phys Chem Chem Phys
	Volume	16	Issue	40	Pages	22299-22308
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We have performed a first-principles study of the p- and n-type conductivity in CuIn1−xGaxSe2 due to native point defects, based on the HSE06 hybrid functional. Band alignment shows that the band gap becomes larger with x due to the increasing conduction band minimum, rendering it hard to establish n-type conductivity in CuGaSe2. From the defect formation energies, we find that In/GaCu is a shallow donor, while VCu, VIn/Ga and CuIn/Ga act as shallow acceptors. Using the total charge neutrality of ionized defects and intrinsic charge carriers to determine the Fermi level, we show that under In-rich growth conditions InCu causes strongly n-type conductivity in CuInSe2. Under increasingly In-poor growth conditions, the conductivity type in CuInSe2 alters to p-type and compensation of the acceptors by InCu reduces, as also observed in photoluminescence experiments. In CuGaSe2, the native acceptors pin the Fermi level far away from the conduction band minimum, thus inhibiting n-type conductivity. On the other hand, CuGaSe2 shows strong p-type conductivity under a wide range of Ga-poor growth conditions. Maximal p-type conductivity in CuIn1−xGaxSe2 is reached under In/Ga-poor growth conditions, in agreement with charge concentration measurements on samples with In/Ga-poor stoichiometry, and is primarily due to the dominant acceptor CuIn/Ga.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge	Editor
	Language		Wos	000343072800042	Publication Date	2014-09-05
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1463-9076;1463-9084;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.123	Times cited	43	Open Access
	Notes	; We gratefully acknowledge financial support from the science fund FWO-Flanders through project G.0150.13. The first-principles calculations have been carried out on the HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Centre (VSC), supported financially by the Hercules foundation and the Flemish Government (EWI Department). We also like to thank Prof. S. Siebentritt of the University of Luxembourg for a presentation of her work on GIGS during a visit to our research group and for helpful discussions of our results. ;			Approved	Most recent IF: 4.123; 2014 IF: 4.493
	Call Number	UA @ lucian @ c:irua:120465			Serial	2284
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	Author	Amini, M.N.; Dixit, H.; Saniz, R.; Lamoen, D.; Partoens, B.
	Title	The origin of p-type conductivity in ZnM₂O₄ (M = Co, Rh, Ir) spinels			Type	A1 Journal article
	Year	2014	Publication	Physical chemistry, chemical physics	Abbreviated Journal	Phys Chem Chem Phys
	Volume	16	Issue	6	Pages	2588-2596
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	ZnM2O4 (M = Co, Rh, Ir) spinels are considered as a class of potential p-type transparent conducting oxides (TCOs). We report the formation energy of acceptor-like defects using first principles calculations with an advanced hybrid exchange-correlation functional (HSE06) within density functional theory (DFT). Due to the discrepancies between the theoretically obtained band gaps with this hybrid functional and the – scattered – experimental results, we also perform GW calculations to support the validity of the description of these spinels with the HSE06 functional. The considered defects are the cation vacancy and antisite defects, which are supposed to be the leading source of disorder in the spinel structures. We also discuss the band alignments in these spinels. The calculated formation energies indicate that the antisite defects ZnM (Zn replacing M, M = Co, Rh, Ir) and VZn act as shallow acceptors in ZnCo2O4, ZnRh2O4 and ZnIr2O4, which explains the experimentally observed p-type conductivity in those systems. Moreover, our systematic study indicates that the ZnIr antisite defect has the lowest formation energy in the group and it corroborates the highest p-type conductivity reported for ZnIr2O4 among the group of ZnM2O4 spinels. To gain further insight into factors affecting the p-type conductivity, we have also investigated the formation of localized small polarons by calculating the self-trapping energy of the holes.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge	Editor
	Language		Wos	000329926700040	Publication Date	2013-12-03
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1463-9076;1463-9084;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.123	Times cited	47	Open Access
	Notes	Fwo; Goa; Hercules			Approved	Most recent IF: 4.123; 2014 IF: 4.493
	Call Number	UA @ lucian @ c:irua:114829			Serial	2525
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	Author	Amini, M.N.; Saniz, R.; Lamoen, D.; Partoens, B.
	Title	The role of the V_Zn-N_O-H complex in the p-type conductivity in ZnO			Type	A1 Journal article
	Year	2015	Publication	Physical chemistry, chemical physics	Abbreviated Journal	Phys Chem Chem Phys
	Volume	17	Issue	17	Pages	5485-5489
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	Past research efforts aiming at obtaining stable p-type ZnO have been based on complexes involving nitrogen doping. A recent experiment by (J. G. Reynolds et al., Appl. Phys. Lett., 2013, 102, 152114) demonstrated a significant ([similar]1018 cm−3) p-type behavior in N-doped ZnO films after appropriate annealing. The p-type conductivity was attributed to a VZnNOH shallow acceptor complex, formed by a Zn vacancy (VZn), N substituting O (NO), and H interstitial (Hi). We present here a first-principles hybrid functional study of this complex compared to the one without hydrogen. Our results confirm that the VZnNOH complex acts as an acceptor in ZnO. We find that H plays an important role, because it lowers the formation energy of the complex with respect to VZnNO, a complex known to exhibit (unstable) p-type behavior. However, this additional H atom also occupies the hole level at the origin of the shallow behavior of VZnNO, leaving only two states empty higher in the band gap and making the VZnNOH complex a deep acceptor. Therefore, we conclude that the cause of the observed p-type conductivity in experiment is not the presence of the VZnNOH complex, but probably the formation of the VZnNO complex during the annealing process.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge	Editor
	Language		Wos	000349616400080	Publication Date	2015-01-20
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1463-9076;1463-9084;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.123	Times cited	20	Open Access
	Notes	FWO G021614N; FWO G015013; FWO G018914N; GOA; Hercules			Approved	Most recent IF: 4.123; 2015 IF: 4.493
	Call Number	c:irua:123218			Serial	3592
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	Author	Dixit, H.; Saniz, R.; Cottenier, S.; Lamoen, D.; Partoens, B.
	Title	Electronic structure of transparent oxides with the Tran-Blaha modified Becke-Johnson potential			Type	A1 Journal article
	Year	2012	Publication	Journal of physics : condensed matter	Abbreviated Journal	J Phys-Condens Mat
	Volume	24	Issue	20	Pages	205503-205503,9
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We present electronic band structures of transparent oxides calculated using the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. We studied the basic n-type conducting binary oxides In2O3, ZnO, CdO and SnO2 along with the p-type conducting ternary oxides delafossite CuXO2 (X = Al, Ga, In) and spinel ZnX2O4 (X = Co, Rh, Ir). The results are presented for calculated band gaps and effective electron masses. We discuss the improvements in the band gap determination using TB-mBJ compared to the standard generalized gradient approximation (GGA) in density functional theory (DFT) and also compare the electronic band structure with available results from the quasiparticle GW method. It is shown that the calculated band gaps compare well with the experimental and GW results, although the electron effective mass is generally overestimated.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000303507100009	Publication Date	2012-04-27
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0953-8984;1361-648X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.649	Times cited	113	Open Access
	Notes	Iwt; Fwo			Approved	Most recent IF: 2.649; 2012 IF: 2.355
	Call Number	UA @ lucian @ c:irua:98222			Serial	1017
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	Author	Dabaghmanesh, S.; Saniz, R.; Amini, M.N.; Lamoen, D.; Partoens, B.
	Title	Perovskite transparent conducting oxides : an ab initio study			Type	A1 Journal article
	Year	2013	Publication	Journal of physics : condensed matter	Abbreviated Journal	J Phys-Condens Mat
	Volume	25	Issue	41	Pages	415503
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
	Abstract	We present an ab initio study of the electronic structure and of the formation energies of various point defects in BaSnO3 and SrGeO3. We show that La and Y impurities substituting Ba or Sr are shallow donors with a preferred 1 + charge state. These defects have a low formation energy within all the suitable equilibrium growth conditions considered. Oxygen vacancies behave as shallow donors as well, preferring the 2 + charge state. Their formation energies, however, are higher in most growth conditions, indicating a limited contribution to conductivity. The calculated electron effective mass in BaSnO3, with a value of 0.21 me, and the very high mobility reported recently in La-doped BaSnO3 single-crystals, suggest that remarkably low scattering rates can be achieved in the latter. In the case of SrGeO3, our results point to carrier density and mobility values in the low range for typical polycrystalline TCOs, in line with experiment.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000324920400011	Publication Date	2013-09-24
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0953-8984;1361-648X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.649	Times cited	17	Open Access
	Notes	FWO;Hercules			Approved	Most recent IF: 2.649; 2013 IF: 2.223
	Call Number	UA @ lucian @ c:irua:110495			Serial	2574
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	Author	Dixit, H.; Saniz, R.; Lamoen, D.; Partoens, B.
	Title	The quasiparticle band structure of zincblende and rocksalt ZnO			Type	A1 Journal article
	Year	2010	Publication	Journal of physics : condensed matter	Abbreviated Journal	J Phys-Condens Mat
	Volume	22	Issue	12	Pages	125505,1-125505,7
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We present the quasiparticle band structure of ZnO in its zincblende (ZB) and rocksalt (RS) phases at the Γ point, calculated within the GW approximation. The effect of the pd hybridization on the quasiparticle corrections to the band gap is discussed. We compare three systems, ZB-ZnO which shows strong pd hybridization and has a direct band gap, RS-ZnO which is also hybridized but includes inversion symmetry and therefore has an indirect band gap, and ZB-ZnS which shows a weaker hybridization due to a change of the chemical species from oxygen to sulfur. The quasiparticle corrections are calculated with different numbers of valence electrons in the Zn pseudopotential. We find that the Zn20 + pseudopotential is essential for the adequate treatment of the exchange interaction in the self-energy. The calculated GW band gaps are 2.47 eV and 4.27 eV respectively, for the ZB and RS phases. The ZB-ZnO band gap is underestimated compared to the experimental value of 3.27 by ~ 0.8 eV. The RS-ZnO band gap compares well with the experimental value of 4.5 eV. The underestimation for ZB-ZnO is correlated with the strong pd hybridization. The GW band gap for ZnS is 3.57 eV, compared to the experimental value of 3.8 eV.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000275496600010	Publication Date	2010-03-13
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0953-8984;1361-648X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.649	Times cited	53	Open Access
	Notes	Iwt; Fwo; Bof-Nio			Approved	Most recent IF: 2.649; 2010 IF: 2.332
	Call Number	UA @ lucian @ c:irua:81531			Serial	2802
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	Author	Sarmadian, N.; Saniz, R.; Partoens, B.; Lamoen, D.
	Title	Ab initio study of shallow acceptors in bixbyite V₂O₃			Type	A1 Journal article
	Year	2015	Publication	Journal of applied physics	Abbreviated Journal	J Appl Phys
	Volume	117	Issue	117	Pages	015703
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We present the results of our study on p-type dopability of bixbyite V2O3 using the Heyd, Scuseria, and Ernzerhof hybrid functional (HSE06) within the density functional theory (DFT) formalism. We study vanadium and oxygen vacancies as intrinsic defects and substitutional Mg, Sc, and Y as extrinsic defects. We find that Mg substituting V acts as a shallow acceptor, and that oxygen vacancies are electrically neutral. Hence, we predict Mg-doped V2O3 to be a p-type conductor. Our results also show that vanadium vacancies are relatively shallow, with a binding energy of 0.14 eV, so that they might also lead to p-type conductivity.
	Address
	Corporate Author				Thesis
	Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
	Language		Wos	000347958600067	Publication Date	2015-01-05
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-8979;1089-7550;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.068	Times cited	3	Open Access
	Notes	FWO G015013; Hercules			Approved	Most recent IF: 2.068; 2015 IF: 2.183
	Call Number	c:irua:122728			Serial	35
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	Author	Bekaert, J.; Saniz, R.; Partoens, B.; Lamoen, D.
	Title	First-principles study of carbon impurities in CuInSe₂ and CuGaSe₂, present in non-vacuum synthesis methods			Type	A1 Journal article
	Year	2015	Publication	Journal of applied physics	Abbreviated Journal	J Appl Phys
	Volume	117	Issue	117	Pages	015104
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	A first-principles study of the structural and electronic properties of carbon impurities in CuInSe2 and CuGaSe2 is presented. Carbon is present in organic molecules in the precursor solutions used in non-vacuum growth methods for CuInSe2 and CuGaSe2 based photovoltaic cells. These growth methods make more efficient use of material, time, and energy than traditional vacuum methods. The formation energies of several carbon impurities are calculated using the hybrid HSE06 functional. C Cu acts as a shallow donor, CIn and interstitial C yield deep donor levels in CuInSe2, while in CuGaSe2 CGa and interstitial C act as deep amphoteric defects. So, these defects reduce the majority carrier (hole) concentration in p-type CuInSe2 and CuGaSe2 by compensating the acceptor levels. The deep defects are likely to act as recombination centers for the photogenerated charge carriers and are thus detrimental for the performance of the photovoltaic cells. On the other hand, the formation energies of the carbon impurities are high, even under C-rich growth conditions. Thus, few C impurities will form in CuInSe2 and CuGaSe2 in thermodynamic equilibrium. However, the deposition of the precursor solution in non-vacuum growth methods presents conditions far from thermodynamic equilibrium. In this case, our calculations show that C impurities formed in non-equilibrium tend to segregate from CuInSe2 and CuGaSe2 by approaching thermodynamic equilibrium, e.g., via thorough annealing.
	Address
	Corporate Author				Thesis
	Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
	Language		Wos	000347958600055	Publication Date	2015-01-07
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-8979;1089-7550;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.068	Times cited	6	Open Access
	Notes	FWO G015013; Hercules			Approved	Most recent IF: 2.068; 2015 IF: 2.183
	Call Number	c:irua:122064			Serial	1215
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	Author	Amini, M.N.; Saniz, R.; Lamoen, D.; Partoens, B.
	Title	Hydrogen impurities and native defects in CdO			Type	A1 Journal article
	Year	2011	Publication	Journal of applied physics	Abbreviated Journal	J Appl Phys
	Volume	110	Issue	6	Pages	063521,1-063521,7
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We have used first-principles calculations based on density functional theory to study point defects in CdO within the local density approximation and beyond (LDA+U). Hydrogen interstitials and oxygen vacancies are found to act as shallow donors and can be interpreted as the cause of conductivity in CdO. Hydrogen can also occupy an oxygen vacancy in its substitutional form and also acts as a shallow donor. Similar to what was found for ZnO and MgO, hydrogen creates a multicenter bond with its six oxygen neighbors in CdO. The charge neutrality level for native defects and hydrogen impurities has been calculated. It is shown that in the case of native defects, it is not uniquely defined. Indeed, this level depends highly on the chemical potentials of the species and one can obtain different values for different end states in the experiment. Therefore, a comparison with experiment can only be made if the chemical potentials of the species in the experiment are well defined. However, for the hydrogen interstitial defect, since this level is independent of the chemical potential of hydrogen, one can obtain a unique value for the charge neutrality level. We find that the Fermi level stabilizes at 0.43 eV above the conduction band minimum in the case of the hydrogen interstitial defect, which is in good agreement with the experimentally reported value of 0.4 eV.
	Address
	Corporate Author				Thesis
	Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
	Language		Wos	000295619300041	Publication Date	2011-09-23
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-8979;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.068	Times cited	13	Open Access
	Notes	; The authors gratefully acknowledge financial support from the IWT-Vlaanderen through the ISIMADE project, the FWO-Vlaanderen through Project G.0191.08 and the BOF-NOI of the University of Antwerp. This work was carried out using the HPC infrastructure at the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center VSC. ;			Approved	Most recent IF: 2.068; 2011 IF: 2.168
	Call Number	UA @ lucian @ c:irua:93613			Serial	1533
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	Author	Saniz, R.; Norman, M.R.; Freeman, A.J.
	Title	Orbital mixing and nesting in the bilayer manganites La_2-2xSr_1+2xMn₂O₇			Type	A1 Journal article
	Year	2008	Publication	Physical review letters	Abbreviated Journal	Phys Rev Lett
	Volume	101	Issue	23	Pages	236402-236404
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	A first principles study of La(2-2x)Sr(1+2x)Mn(2)O(7) compounds for doping levels 0.3 <= x <= 0.5 shows that the low energy electronic structure of the majority spin carriers is determined by strong momentum-dependent interactions between the Mn e(g) d(x)(2)-y(2) and d(3z)(2)-r(2) orbitals, which, in addition to an x-dependent Jahn-Teller distortion, differ in the ferromagnetic and antiferromagnetic phases. The Fermi surface exhibits nesting behavior that is reflected by peaks in the static susceptibility, whose positions as a function of momentum have a nontrivial dependence on x.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York, N.Y.	Editor
	Language		Wos	000261431200045	Publication Date	2008-12-03
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0031-9007;1079-7114;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	8.462	Times cited	14	Open Access
	Notes				Approved	Most recent IF: 8.462; 2008 IF: 7.180
	Call Number	UA @ lucian @ c:irua:102602			Serial	2498
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	Author	Saniz, R.; Dixit, H.; Lamoen, D.; Partoens, B.
	Title	Quasiparticle energies and uniaxial pressure effects on the properties of SnO₂			Type	A1 Journal article
	Year	2010	Publication	Applied physics letters	Abbreviated Journal	Appl Phys Lett
	Volume	97	Issue		Pages	261901-261901,3
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We calculate the quasiparticle energy spectrum of SnO2 within the GW approximation, properly taking into account the contribution of core levels to the energy corrections. The calculated fundamental gap is of 3.85 eV. We propose that the difference with respect to the experimental optical gap (3.6 eV) is due to excitonic effects in the latter. We further consider the effect applied on uniaxial pressure along the c-axis. Compared to GW, the effect of pressure on the quasiparticle energies and band gap is underestimated by the local-density approximation. The quasiparticle effective masses, however, appear to be well described by the latter.
	Address
	Corporate Author				Thesis
	Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
	Language		Wos	000285768100015	Publication Date	2010-12-28
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0003-6951;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.411	Times cited	23	Open Access
	Notes	Iwt; Fwo; Bof-Noi			Approved	Most recent IF: 3.411; 2010 IF: 3.841
	Call Number	UA @ lucian @ c:irua:85759			Serial	2803
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	Author	Saniz, R.; Xu, Y.; Matsubara, M.; Amini, M.N.; Dixit, H.; Lamoen, D.; Partoens, B.
	Title	A simplified approach to the band gap correction of defect formation energies : Al, Ga, and In-doped ZnO			Type	A1 Journal article
	Year	2013	Publication	The journal of physics and chemistry of solids	Abbreviated Journal	J Phys Chem Solids
	Volume	74	Issue	1	Pages	45-50
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	The calculation of defect levels in semiconductors within a density functional theory approach suffers greatly from the band gap problem. We propose a band gap correction scheme that is based on the separation of energy differences in electron addition and relaxation energies. We show that it can predict defect levels with a reasonable accuracy, particularly in the case of defects with conduction band character, and yet is simple and computationally economical. We apply this method to ZnO doped with group III elements (Al, Ga, In). As expected from experiment, the results indicate that Zn substitutional doping is preferred over interstitial doping in Al, Ga, and In-doped ZnO, under both zinc-rich and oxygen-rich conditions. Further, all three dopants act as shallow donors, with the +1 charge state having the most advantageous formation energy. Also, doping effects on the electronic structure of ZnO are sufficiently mild so as to affect little the fundamental band gap and lowest conduction bands dispersion, which secures their n-type transparent conducting behavior. A comparison with the extrapolation method based on LDA+U calculations and with the HeydScuseriaErnzerhof hybrid functional (HSE) shows the reliability of the proposed scheme in predicting the thermodynamic transition levels in shallow donor systems.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York, N.Y.	Editor
	Language		Wos	000311062500009	Publication Date	2012-08-10
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0022-3697;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.059	Times cited	36	Open Access
	Notes	Fwo; Bof-Nio			Approved	Most recent IF: 2.059; 2013 IF: 1.594
	Call Number	UA @ lucian @ c:irua:101782			Serial	3004
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