Perspectives of the concept of van der Waals epitaxy: growth of lattice mismatched GaSe (0001) films on Si(111), Si(110) and Si(100)

The preparation of high quality epitaxial heterointerfaces of lattice misma tched dissimilar materials is one of the challenging tasks for advanced sem iconductor devices. We have used the concept of van der Waals epitaxy, name ly the deposition of two-dimensional layered materials like GaSe onto prope rly terminated three-dimensional substrates to prepare new heterointerfaces on Si of different surface orientation. Film growth and properties were in vestigated in situ by low-energy electron diffraction (LEED) and soft X-ray photoemission (SXPS) using integrated UHV preparation and analysis chamber s. On Si(111) a hexagonal GaSe epitaxial layer grows on top of a preformed Si-Ga-Se van der Waals-like termination layer. A distorted Si-Ga-Se layer i s also formed on Si(110), which evidently leads to an hexagonal surface mes h as substrate for further growth of crystalline GaSe. On Si(100), two doma ins of azimuthally aligned GaSe(0001) films are deposited. The usually give n constraints in lattice mismatch, and even of different surface symmetry, can evidently be overcome by the use of van der Waals-like surface terminat ion layers of the substrates. Thus, novel device structures combining compo und semiconductors with Si seem to be feasible. (C) 2000 Elsevier Science B .V. All rights reserved.