Behavior of N atoms after thermal nitridation of Si1 − xGex surface

Abstract

Behavior of N atoms after thermal nitridation of Si1−xGex (100) surface in NH3 atmosphere at 400°C 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 H2 at 400°C. For nitrided Si0.3Ge0.7(100), the bonding between N and Si atoms forms Si3N4 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), Si0.3Ge0.7(100) and Ge(100). From these results, it is suggested that penetration of N atoms through around a few atomic layers for Si, Si0.3Ge0.7 and Ge occurs during nitridation, and the N atoms for the nitrided Si0.3Ge0.7(100) dominantly form a Si3N4 structure which stably remains even during heat treatment in H2 at 400°C.