Liquid Phase Epitaxy

Abstract

Liquid phase epitaxy (LPE) is the deposition from a liquid phase (a solution or melt) of a thin single crystalline layer isostructural with the substrate crystal [5.1]. Usually LPE is performed using a solution as the liquid phase, because this is advantageous against the cases when a melt is used. In comparison to the growth from melts, growth from solutions:(i)allows for epitaxy at lower temperatures(ii)enables better control of the amount of the crystalline phase grown or removed by dissolution(iii)leads to crystallization of layers with lower densities of defects, whether intrinsic (point defects) or extrinsic (e.g., impurities dissolved from crucible material)(iv)makes it possible to grow layers sequentially from a series of solutions of differing composition, but with very similar and readily controlled liquidus temperature (liquidus is the border-line on the ``temperature---concentration (composition)'' phase diagram between the pure liquid region and the solid---liquid co-existence region (see Sect. 11.3)), and last but not least(v)allows for considerable reduction of the vapor pressure of volatile components of the compounds (e.g., P in the case of InP and As in the case of GaAs) by working at temperatures far below the melting point.