Behavior of N atoms after thermal nitridation of Si_(1-x)Ge_x surface

摘要

Behavior of N atoms after thermal nitridation of Si_(1-x)Ge_x(100) surface in NH_3 atmosphere at 400 ℃ was investigated. X-ray photoelectron spectroscopy (XPS) results show that N atomic amount after nitridation tends to increase with increasing Ge fraction, and amount of N atoms bonded with Ge atoms decreases by heat treatment in H_2 at 400 ℃. For nitrided Si_(0.3)Ge_(0.7) (100), the bonding between N and Si atoms forms Si_3N_4 structure whose amount is larger than that for nitrided Si(100). Angle-resolved XPS measurements show that there are N atoms not only at the outermost surface but also beneath surface especially in a deeper region around a few atomic layers for the nitrided Si(100), Si_(0.3)Ge_(0.7)(100) and Ge(100). From these results, it is suggested that penetration of N atoms through around a few atomic layers for Si, Si_(0.3)Ge_(0.7) and Ge occurs during nitridation, and the N atoms for the nitrided Si_(0.3)Ge_(0.7)(100) dominantly form a Si_3N_4 structure which stably remains even during heat treatment in H_2 at 400 ℃.