INVESTIGATION OF THE GROWTH-MECHANISM OF LAYERED SEMICONDUCTOR GASE

Heteroepitaxial films of lamellar semiconductor GaSe were grown on MoS 2 cleaved surfaces by molecular beam epitaxy and its growth mechanism was investigated by atomic force microscope. At the initial stage of t he growth, triangular islands of GaSe with a unit layer thickness are formed, There exist two types of domains, which have opposite orientat ions of the triangles, It is suggested that the difference in the orie ntation corresponds to the difference in stacking positions of Se-Ga-G a-Se four hexagonal atomic sheets in the unit layer. It is also reveal ed that stacking polytypes of GaSe can he determined by observing the orientation of triangular islands in each unit layer in a multilayer f ilm. Most of GaSe films have the epsilon- and/or gamma-type slacking. But some domains really have the beta-type one which rarely appear in a hulk single-crystal of GaSe.