Defect levels through hybrid density functionals: Insights and applications

被引:263
作者
Alkauskas, Audrius [1 ,2 ]
Broqvist, Peter [1 ,2 ]
Pasquarello, Alfredo [1 ,2 ]
机构
[1] Ecole Polytech Fed Lausanne, Inst Theoret Phys, CH-1015 Lausanne, Switzerland
[2] PHB Ecublens, Inst Romand Rech Numer Phys Mat, CH-1015 Lausanne, Switzerland
来源
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS | 2011年 / 248卷 / 04期
基金
瑞士国家科学基金会;
关键词
defects; defect levels; density functional theory; hybrid functionals; BAND-GAPS; ELECTRONIC-PROPERTIES; HARTREE-FOCK; ENERGIES; EXCHANGE; SEMICONDUCTORS; IMPURITIES; CHEMISTRY; VACANCIES; OFFSETS;
D O I
10.1002/pssb.201046195
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
Hybrid density functional calculations applied to defect charge transition levels are explored in the attempt to overcome the band-gap problem of semilocal density functionals. Charge transition levels of a large set of point defects calculated with semilocal and hybrid density functionals are found to correspond closely when aligned with respect to the average electrostatic potential. This strongly suggests that the defect levels defined in this way are already accurately described at these levels of theory. In particular, this then also applies to the energy separation between different defect levels, which is directly accessible experimentally. At variance, within the same alignment scheme, the band edges obtained with hybrid functionals are found to undergo significant shifts with respect to those obtained with semilocal functionals. While these shifts systematically give larger band gaps, the agreement with experiment is not always satisfactory when a fixed fraction of exact exchange is admixed. This describes a current limitation of hybrid functional schemes. In the attempt of identifying a viable theoretical description within the class of one-parameter hybrid functionals based on bare exchange, we explore the validity of the empirical procedure which consists in tuning the fraction of nonlocal exchange to a value which gives a theoretical band gap reproducing the experimental one. Comparisons with experiment for band offsets and specific defect levels record very encouraging results. Despite its inherent limitations, such an empirical scheme based on hybrid functionals represents a definite improvement with respect to semilocal functionals. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
引用
收藏
页码:775 / 789
页数:15
相关论文
共 91 条
[1]   Band alignment and defect states at SiC/oxide interfaces [J].
Afanas'ev, VV ;
Ciobanu, F ;
Dimitrijev, S ;
Pensl, G ;
Stesmans, A .
JOURNAL OF PHYSICS-CONDENSED MATTER, 2004, 16 (17) :S1839-S1856
[2]   Intrinsic n-Type Behavior in Transparent Conducting Oxides: A Comparative Hybrid-Functional Study of In2O3, SnO2, and ZnO [J].
Agoston, Peter ;
Albe, Karsten ;
Nieminen, Risto M. ;
Puska, Martti J. .
PHYSICAL REVIEW LETTERS, 2009, 103 (24)
[3]  
Alkauskas A., UNPUB
[4]   Effect of improved band-gap description in density functional theory on defect energy levels in α-quartz [J].
Alkauskas, Audrius ;
Pasquarello, Alfredo .
PHYSICA B-CONDENSED MATTER, 2007, 401 :670-673
[5]   Alignment of hydrogen-related defect levels at the Si-SiO2 interface [J].
Alkauskas, Audrius ;
Pasquarello, Alfredo .
PHYSICA B-CONDENSED MATTER, 2007, 401 (546-549) :546-549
[6]   Charge state of the O2 molecule during silicon oxidation through hybrid functional calculations [J].
Alkauskas, Audrius ;
Broqvist, Peter ;
Pasquarello, Alfredo .
PHYSICAL REVIEW B, 2008, 78 (16)
[7]   Defect energy levels in density functional calculations: Alignment and band gap problem [J].
Alkauskas, Audrius ;
Broqvist, Peter ;
Pasquarello, Alfredo .
PHYSICAL REVIEW LETTERS, 2008, 101 (04)
[8]  
[Anonymous], LANDOLTBORNSTEIN DAT
[9]   DENSITY-FUNCTIONAL THERMOCHEMISTRY .3. THE ROLE OF EXACT EXCHANGE [J].
BECKE, AD .
JOURNAL OF CHEMICAL PHYSICS, 1993, 98 (07) :5648-5652
[10]   Multiscale modeling of oxygen diffusion through the oxide during silicon oxidation [J].
Bongiorno, A ;
Pasquarello, A .
PHYSICAL REVIEW B, 2004, 70 (19) :1-14