Surface science at atmospheric pressure: Reconstructions on (001) GaAs in organometallic chemical vapor deposition

We report the first observation of reconstructions on semiconductor surfaces in atmospheric pressure (AP) environments. Using reflectance-difference spectroscopy we show that the primary reconstructions that occur on (001) GaAs in ultrahigh vacuum (UHV) also occur under AP, H₂, He, and N₂. These results demonstrate that dimer formation is not restrited to surfaces in UHV and justify the use of UHV studies to determine (001) GaAs chemistry during AP organometaliic chemical vapor deposition (OMCVD). Reconstructions observed during OMCVD growth are inconsistent with previous models and provide new insights concerning growth.