SURFACTANT-MEDIATED GROWTH OF INDIUM ON GAAS(001)

The influence of antimony as surfactant on the growth mode of indium o n GaAs(001) has been investigated for deposition at various temperatur es. Clean surfaces of (2 x 4) reconstruction were prepared in UHV by t hermal desorption of a protective arsenic cap deposited on top of homo epitaxially grown MBE layers. Before In deposition, 2 ML Sb were pre-d eposited 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 occurr ing during In growth on GaAs without an Sb interlayer. After removal o f the samples from UHV, SEM investigations show regularly shaped, flat In islands oriented along the [110] substrate directions. In comparis on, 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 formatio n of a continuous In layer, which tears during warm up to room tempera ture. An exchange between surfactant material and indium during growth is found for both low- and room-temperature In deposition. X-ray diff raction measurements show a strong influence of the Sb surfactant on t he crystallinity of the In film.