ICDS Conference, Sendai, Japan, 7.95
Abstract
Local--density--functional calculations using a real--space cluster approach are used to model interstitial hydrogen in GaAs and the dissociation of the C--H and C--H$^-$ complexes. The equilibrium site is found to be on a Ga--As bond axis for H$^0$ and H$^+$ an d at a Ga anti--bonding site for H$^-$. It is also shown that a H$_2$ molecule is stable in interstitial space and has a lower energy than the two possible H$_2^*$ defects and than widely separated single interstitial hydrogen atoms. The study of hydrogen in pure GaAs also yields the result that interstitial hydr ogen is a negative--U defect. It is found that the energy barrier to the dissociation of the C--H complex is 1.8 eV, but that this is reduced to 0.9 eV for C--H$^-$. Comparison is made with recent experimental results and implications for current containing devices are discussed.
Keywords: C-H, dissocation, interstitial hydrogen, GaAs, ab initio
C.E. 7.95