NUCLEATION AND GROWTH OF GASE ON GAAS BY VAN-DER-WAAL EPITAXY

Nucleation and growth of GaSe on GaAs(111)B substrate was studied to d evelop a better understanding of the Van der Waals epitaxy (VDWE) proc ess. A complementary combination of RHEED, XPS, AFM and HREM were used . The initial GaAs(111)B surface reacts with incoming flux, forming a compound similar to GaSe at the surface. After one monolayer coverage, further growth of GaSe is on GaSe; the system changes from a heteroep itaxial to homoepitaxial system. Nucleation in the VDWE process is cha racterized by the formation of small oriented clusters with the weak V an der Waals bond dictating the orientation relationship. Further grow th is found to be limited by surface kinetics, with a large diffusion barrier at the growing step edge. This barrier leads to islanding with the island shape dictated by the substrate temperature. A modified de position procedure was developed to obtain uniform layer-by-layer grow th of well-aligned flat GaSe domains without islanding.