Diffusion properties of n-type dopants diffused from spin on glass into Ge

Abstract

Solid phase diffusion properties of three typical n-type dopants (P, As, and Sb) in Ge have been studied through experimental depth profiles of dopants diffused from spin on glass (SOG) films. Numerical calculations of dopant profiles in Ge are performed to extract the diffusion constant through comparison with the experimental profiles. It is pointed out that experimental results of diffusion at low temperature are important to correctly examine the influence of negative charge states of a vacancy on dopant diffusion. It is found that vacancies with the charge states of −2 mediate the diffusion of P and As without implantation-induced defects. The diffusion constants of P and As, obtained in this study, are larger than those for intrinsic diffusion, while that of Sb is almost the same as that for intrinsic diffusion. The present larger diffusion constants of P and As can be explained by the supply of vacancies from Ge surfaces via E-centers during diffusion from SOG.