epitaxial growth of gaas on 100 silicon 34 journal of applied physics vol 61 5 mar 1 1987 the purpose and necessity of low or room temperature deposition is to deposit at a sufficiently low temperature so that deposited atoms are not significantly mobile upon contact with support 12 thereby signaificantly reducing their tendency at higher temperatures to have sufficient mobility at the depositing surface to form islands rather at such low deposition temperatures the deposited atoms will have only sufficient energy to bond and register with the underlying lattice intially forming a uniform continuous film low temperature and or high fluxes are employed in mbe to kinetically capture a thin buffer film 14 with similar growth conditions maintained for initial stages of growth of overlayer 16 until film 14 is uniformly overlayered or encapsulated by the cubic zinc blend compound material once buffer layer 14 has been deposited at or near room temperature it is preferred that the initial stages of epitaxial deposition of overlayer 16 be conducted at a low temperature otherwise if overlayer 16 were deposited at normally higher temperatures required for good deposition the underlying buffer layer 14 would coagulate or ball up forming thick islands or even evaporate therefore the initial stage of low temperature deposition of overlayer 16 has the effect to confine the continuous buffer layer 14 and not permit coagulation due to is weaker bonding properties the low temperature of this initial deposition is dependent upon the chosen compounds for film 14 and overlayer 16 e g it may be between room temperature.