Self-sustaining step-flow growth: Preset nano-terraces as diffusion rails for Si-doped AlN by low-temperature MOCVD

Abstract

Low-temperature doping presents a promising approach to address the challenge of conductivity control in aluminum nitride (AlN), a candidate for next-generation optoelectronics and electronics. However, the metal-organic chemical vapor deposition for high-quality AlN growth typically requires elevated temperatures. To achieve low-temperature AlN growth, we have developed a method to realize a kind of “self-sustaining step-flow growth” by exploiting the inherent controllability of Al adatoms, benefiting from their limited diffusion capability. A comparative study at a growth temperature of 1050 °C demonstrates that this method helps sustain stable step-flow growth, yielding 3 μm high-quality Si-doped AlN with a conductivity of 56.1 kΩ−1 cm−1. The growth temperature can be further reduced to 980 °C, the record-low growth temperature, and the corresponding conductivity is 115 kΩ−1 cm−1. This advancement offers critical insights into the AlN surface kinetics under doping and paves the way for industrial AlN applications as a semiconductor.