Chlorine-Assisted Growth of Epitaxial InGaN and AlGaN Crystals at Low Temperatures Using Plasma-Enhanced Chemical Vapor Deposition

Abstract

The chlorine-assisted growth of epitaxial indium gallium nitride (InGaN) and aluminum gallium nitride (AlGaN) crystals was achieved with high reproducibility at the low temperature of 600 °C in the plasma-enhanced chemical vapor deposition (PECVD) reactor via the reaction between the metal trichlorides with high vapor pressures and nitrogen plasma. After adding hydrogen gas to the growth processes of InGaN and AlGaN, the problems for the etching of chlorine plasma on the as-grown InGaN crystals and the appearance of crystal planes different from (002), derived from the worse and the better bonding abilities of materials, respectively, were solved effectively. Inside AlGaN crystals, the phase separation of gallium nitride (GaN) and aluminum nitride (AlN) can be avoided by controlling the amount of precursor aluminum. The epitaxial InGaN and AlGaN crystals have the same (002) crystal plane as the GaN(002) bottom layers and exhibit the same ⟨0001⟩ crystallographic growth direction along the axial direction of GaN microrods, representing the consistent growth orientation of the epitaxial crystals. The process temperatures of InGaN and AlGaN can be greatly decreased using chlorine gas and plasma so that the related applications of low-temperature growth may be expanded drastically in the future.

Plasma-Assisted Halide Vapor Phase Epitaxy for Low Temperature Growth of III-Nitrides

“…At the same time, plasma has a negative effect on indium concentration because plasma simultaneously activates chlorine-containing species. The relatively poor bonding ability of In compared to Ga in InGaN means that In can be more easily etched by the highly reactive plasma-activated chlorine-containing species and that will result in a lower In concentration [31,32]. In addition, it is also known that the growth of InGaN does not occur when InCl is used since the equilibrium constant of the reaction between InCl and NH 3 is small [33].…”