CHARACTERIZATION AND SUBSTRATE-TEMPERATURE DEPENDENCE OF CRYSTALLINE STATE OF GaAs GROWN BY MOLECULAR BEAM EPITAXY.

A crystal growth technique, MBE (Molecular Beam Expitaxy), is defined as epitaxial growth onto a substrate resulting from the condensation of directed beam of molecules or atoms effused from cells in an ultrahigh vacuum system. MBE technique is a modification of the three temperature method in which the constituent molecules or atoms are supplied by molecular beams. The deposition process on the substrate is far from a thermal equilibrium, and is governed mainly by kinetics. In the case of GaAs, the sticking coefficient of Ga on GaAs surface is unity and that of As is about unity only when there is excess Ga on the surface, otherwise that is nearly equal to zero. This makes it possible to grow a film with stoichiometry. This technique has advantages such as precise controllability of layer thickness and impurity.