Si衬底上分子束外延Ge,Si时的反射式高能电子衍射强度振荡观察

本文观察了在Si(100)和Si(111)衬底上分子束外延Si,Ge时的反射式高能电子衍射(RHEED)强度振荡现象。其振荡特性表明,外延一定厚度的缓冲层可以改善表面的平整性,较慢的生长速率或中断生长一段时间有利于外延膜晶体质量的提高。Si(100)上外延Si或Ge时,沿100]和110]方位观测到的振荡特性均为单原子模式,起因于表面存在双畴(2×1)再构;而Si(111)上外延Ge时,112]方位观测到的振荡为双原子层模式,但在110]方位观察到不均匀周期的强度振荡行为。两种衬底上保持RHEED

RHEED INTENSITY OSCILLATIONS IN THE PROCESS OF MOLECULAR BEAM EPITAXY GROWTH OF Ge AND Si ON Si SUBSTRATES

RHEED intensity oscillations in the process of MBE growth of Ge and Si on Si (100) and Si (111) substrates were observed. It is revealed that a finite-thick buffer layer can improve the surface flatness of Si substrates, and the employment of lower growth rate or growth interruption procedure can improve tke crystal quality of epilayers. During the growth of Ge and Si on Si (100), a single atomic layer mode RHEED intensity oscillation was observed along either 100] or 110] azimuthal direction, which is due to the existance of double domain (2×1)+(1×2) reconstruction on the surface. During the growth of Ge on Si (111) substrates, RHEED intensity oscillation show a bilayer mode observed along 112] azimuth, but a non-uniform periodicity along 110] azimuth. The oscillations for continuosly growing Ge-on either Si (100) or Si (111) could exist up to an epilayer thickness of 6ML, which corresponds to the critical thickness of pseudomorphic growth of Ge on Si.