Molecular Layer Epitaxy

TLDR

The study demonstrates the first successful molecular layer epitaxy (MLE) of GaAs using trimethyl‑gallium and an arsenic‑containing gas. The authors investigated single‑layer MLE growth conditions varying substrate temperature, chamber pressure, cycle admittance, and photoirradiation. MLE growth at 500 °C produced monolayer films whose thickness per cycle saturated with admittance, while higher temperatures and TMG admittance increased growth; electrical properties varied with chamber pressure, with carrier density decreasing as pressure rose and TMG pressure fell, yet all films remained p‑type, and photoirradiation during growth markedly improved surface morphology and electrical performance.

Abstract

We report, for the first time, the success of molecular layer epitaxy (MLE) using as an As containing gas and trimethyl‐gallium (TMG) as a Ga containing gas. Growth conditions for a single layer by layer deposition process were investigated as a function of the substrate temperature, the pressure in the growth chamber, the admittance quantity per cycle, and photoirradiation. The substrate temperature of 500°C fulfilled the conditions for a monolayer growth, where the film thickness per one cycle is saturated with the admittance quantity, at the higher temperature that increased with the TMG admittance quantity. The electrical properties of the film grown by MLE method strongly depended on the gas admittance rate, i.e., pressure in the growth chamber. The carrier density of the film proportionally decreased with increasing pressure and decreasing TMG pressure. However, all growth films show p‐type behavior with a carrier density of . Photoirradiation during the growth by a high pressure Hg lamp, Ar laser (514.5 nm), and with a doubler (257.3 nm) largely improved the surface morphology and electrical properties of the films by MLE.