Fotoenergetikada nanostrukturali yarimo‘tkazgich materiallar II xalqaro ilmiy anjumani

 

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Fotoenergetikada nanostrukturali yarimo‘tkazgich materiallar

II xalqaro ilmiy anjumani 
 
19-20 noyabr 2021 yil 
30 
IONIZATION ENERGY AND DIFFUSION PROFILE OF HYDROGEN IN 
SILICON FROM FIRST-PRINCIPLES CALCULATIONS
 
K. Ruzimov
1
, M. Ganchenkova
3
, and S. Zh. Karazhanov
2,3 
1
Faculty of Physics and Mathematics, Urgench State University, 
 220100 Urgench,Khorezm, Uzbekistan 
2
Department for Solar Energy, Institute for Energy Technology, 
 PO Box 40, 2027 Kjeller, Norway 
3
Department of Materials Science, National Research Nuclear University 
"MEPhI", 31 Kashirskoe sh, 115409, Moscow, Russia 
 
Si is one of the important materials to be used in modern electronic, 
photovoltaic devices and sensors. Hydrogen (H) is one of the light-weight 
elements, which is often present in Si and plays key role in its electrical, optical, 
and structural properties. It can passivate shallow donors and shallow acceptors, 
deep level impurities, interface states, exhibit bistability upon forming complex 
with some group-V impurities, enhance oxygen diffusion in 
p
-Si, lead to formation 
of nanoclusters, etc. Knowledge of its energy levels in the band gap and 
development of methods of studies of them are crucial.
This work presents a study of ionization energy of hydrogen (H) located at 
(or near to) the bond center (BC) in positively charged (H
+
) and neutral states (H
0
) 
and at the antibonding (AB) site in negative charged state (H
-
) for silicon by first-
principles calculations by including the corrections such as the vibrational zero-
point energy, finite-size-scaling, band gap correction, and by hybrid functional. 
Vienna 
ab initio
simulation package (VASP) has been used that calculates the 
Kohn-Sham eigenvalues within the framework of density functional theory (DFT). 
Studies of ground state properties and electronic structure have been performed by 
the generalized gradient approximation with Perdew–Burke–Ernzerhof exchange-
correlation functional and the projector-augmented wave (PAW) method as well as 
Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional.
By considering the 64, 216, 288, 512, and 1000 atom supercells the error 
coming from the artificial interaction between the defect and its images in 
neighboring supercells has been estimated for BC H
+
, BC H
0
, and for AB H
-
. We 
have calculated formation energy for the above models of H and analyzed relative 
stability of them as a function of Fermi level. We show that H
+
is stable for Fermi 
levels from the topmost valence band to E(+/-). At higher Fermi levels up to the 
conduction band negatively charged H is found to be stable. We found that neutral 
state of H is metastable at all Fermi levels. Our theoretical study shows negative-
U
behavior of H in Si. Energy levels of different models of H in Si estimated in this 
work within hybrid functional agrees well with previous theoretical estimations by 
marker method.

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