Indium surface segregation in AlSb and GaSb

The effect of indium surface segregation during the molecular beam epitaxial growth of AlSb and GaSb on In(As,Sb) is investigated using various techniques including reflection high-energy electron diffraction (RHEED), high-resolution transmission electron microscopy (HRTEM), and high-resolution X-ray diffraction (HRXRD). The peculiar RHEED intensity variation observed during the growth of AlSb and GaSb on In(As,Sb) is interpreted as the consequence of indium surface segregation. This is confirmed by HRTEM investigation. The interface width associated with In segregation is found to increase with the growth temperature, as expected for a kinetically limited surface segregation phenomenon. In the investigated growth temperature range (400–540°C), the In segregation length is always higher for GaSb than for AlSb. Finally, a very good agreement between simulated and experimental HRXRD data corresponding to a GaSb/InAs superlattice is obtained by taking into account the In segregation profile deduced from the RHEED data.