The homoepitaxial growth of GaAs(111)A and (111)B by molecular beam epitaxy: an investigation of the temperature-dependent surface reconstructions and bulk electrical conductivity transitions

Static surface phase maps of GaAs(111)A and (111)B have been generated for a variety of incident As4 flux and substrate temperature conditions. Below a critical As4 flux of JAs4c approximately=5*1015 molecules/cm2 four GaAs(111)B surface reconstructions were identified (namely (2*2), (1*1)LT, ( square root 19* square root 19), and (1*1)HT); however, above JAs4c the ( square root 19* square root 19) surface phase was eradicated such that the (1*1)LT and (1*1)HT structures were linked together to form a single (1*1) phase. Only a (2*2) reconstruction was observed on the GaAs(111)A surface. Si-doped GaAs(111) variable growth temperature (TG) studies were performed, resulting in p-type GaAs(111)A and n-type GaAs(111)B epilayers. Growth temperature-induced bulk electrical conductivity transitions were found on both of the GaAs(111) crystallographic orientations. These conducting/nonconducting transitions were accompanied by a degradation in the 'quality' of the GaAs(111)A surface structure, and were related in the GaAs(111)B case to a change in the dynamic surface reconstruction. During deposition the GaAs(111)A (2*2) reconstruction was found to persist for TG>or=525 degrees C; but for TG<525 degrees C faceted surfaces were produced.