Bandgap engineering of indium gallium nitride layers grown by plasma-enhanced chemical vapor deposition

This paper reports on the fabrication of In xGa 1 - xN (InGaN) layers with various compositions ranging from InN to GaN using a cost-effective low-temperature plasma-enhanced chemical vapor deposition (PECVD) method and analyzes the influence of deposition parameters on the resulting films. Single-phase nanocrystalline InGaN films with crystallite size up to 30 nm are produced with deposition temperatures in the range of 180-250 ? using the precursors trimethylgallium, trimethylindium, hydrogen, nitrogen, and ammonia in a parallel-plate type RF-PECVD reactor. It is found that growth rate is a primary determinant of crystallinity, with rates below 6 nm/min producing the most crystalline films across a range of several compositions. Increasing In content leads to a decrease in the optical bandgap, following Vegard's law, with bowing being more pronounced at higher growth rates. Significant free-carrier absorption is observed in In-rich films, suggesting that the highly measured optical bandgap (about 1.7 eV) is due to the Burstein-Moss shift. (C) 2022 Author(s).

Automated summary

This paper reports on the fabrication of InGaN layers with various compositions using a low-temperature PECVD method and analyzes the influence of deposition parameters on the resulting films. The growth rate and In content are found to affect the crystallinity and optical properties of the films.