Surfactant-mediated growth of indium on GaAs(001)

The influence of antimony as surfactant on the growth mode of indium on GaAs(001) has been investigated for deposition at various temperatures. Clean surfaces of (2 x 4) reconstruction were prepared in UHV by thermal desorption of a protective arsenic cap deposited on top of homoepitaxially grown MBE layers. Before In deposition, 2 ML Sb were pre-deposited on top of the clean GaAs surface of part of the samples. The In growth mode was then monitored by AES and compared with that occurring during In growth on GaAs without an Sb interlayer. After removal of the samples from UHV, SEM investigations show regularly shaped, flat In islands oriented along the [110] substrate directions. In comparison, In islands grown without an Sb interlayer also show a preferential orientation along the [110] substrate directions, but differ in shape and size. Low-temperature In deposition (120 K) leads to the formation of a continuous In layer, which tears during warm up to room temperature. An exchange between surfactant material and indium during growth is found for both low- and room-temperature In deposition. X-ray diffraction measurements show a strong influence of the Sb surfactant on the crystallinity of the In film.