Real time in situ observation of (001)GaAs in OMCVD by reflectance difference spectroscopy

Abstract

We report the first direct observation of reconstructions of semiconductor surfaces in atmospheric pressure (AP) environments. We use reflectance difference spectroscopy (RDS), a surface-sensitive optical probe, to bridge the gap between ultrahigh vacuum (UHV) and AP, and show that the primary surface reconstructions that occur on (001)GaAs surfaces in UHV also occur in the AP environments used with organometallic chemical vapor deposition (OMCVD). Our results justify the applicability of the results of UHV surface science to understanding surfaces under non-UHV environments. Our results also show that during OMCVD growth conditions the surface is terminated with multilayers of As, contrary to generally accepted models. We also apply our newly developed approach, multi-transient spectroscopy (MTS), to the study of atomic layer epitaxy (ALE). Using MTS, we observe surface spectra within a time resolution of 100 ms during actual ALE growth cycles, thus allowing the dynamics of surface reactions to be investigated.