Liquid‐Phase Epitaxy

Abstract

Liquid‐phase epitaxy (LPE) is a crystal growth method that produces single‐crystal films or layers of semiconductors and other types of materials on a supporting substrate. LPE‐grown structures include light‐emitting diodes (LEDs), laser diodes, and photodetectors; energy conversion devices such as photovoltaic cells, and various magnetic and optical devices. LPE is typically affected by solidifying a film comprising solute components precipitated from a molten metallic solution at temperatures ranging from several hundred to >1200 °C. A common LPE technology is based on a crucible slider apparatus in a temperature‐programmed furnace with a hydrogen ambient at atmospheric pressure. Multiple layer depositions generate a wide range of structures, and LPE has proven especially useful for III–V compound semiconductor heterostructures. Present‐day uses of LPE stem from favorable features such as fast growth rates, low defect densities, a wide choice of impurity dopants, and straightforward formulations based on phase equilibria and kinetics data and models. While LPE was a prominent epitaxy technology in the 1970s and 1980s, nowadays LPE is relegated to niche applications. Compared to competing epitaxy technologies such as molecular beam epitaxy (MBE) and metal–organic chemical vapor deposition (MOCVD), LPE falls short with regard to the achievement of ultrathin layered structures, strained or lattice‐mismatched structures, abrupt interfaces, and areal uniformity. Still, there are significant application areas well served by LPE or by modified LPE techniques, as reviewed here.