Open AccessBipolaron mechanism of DX center in AlxGa1-xAs:Si
Author(s) -
Weifeng Li,
Liang Ying-Xin,
Jin Ye,
Jianhua Wei
Publication year - 2010
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.59.8850
Subject(s) - bipolaron , polaron , condensed matter physics , ground state , lattice (music) , electron , doping , materials science , thermal conduction , electronic structure , conduction band , physics , atomic physics , thermodynamics , quantum mechanics , acoustics
The free-carrier concentration in Si-doped AlxGa1-xAs has been calculated by grand-canonical-ensemble statistics without any fitting parameters. Our results are quantitatively in agreement with various experimental data in the temperature range 77—300 K, which indicates that the physical picture of the ground state of DX center (DX-) is of an electronic bipolaron due to the interaction between excess electrons and lattice. When exposed to light, one bipolaron can turn into a polaron, meantime release one electron to the conduction band accompanied by lattice relaxations. Our calculations also prove that DX0 is unstable at thermal equilibrium, which further confirms our bipolaron mechanism.