Spatial distribution study of a nitrogen plasma in an ion-filtered inductively coupled plasma used to grow GaN films

Abstract

The spatial distribution of N2 plasma in the reactor chamber of an ion-filtered inductively-coupled-plasma metal-organic-chemical-vapor-deposition (IF-ICP-MOCVD) was studied. The selective absorption of the ion filter with a showerhead structure was simulated based on the simplification of the reaction model of N2 plasma and demonstrated by the optical emission spectroscopy and the growth of GaN film. The simulation shows that the number density of nitrogen ions on the pedestal was reduced by one order of magnitude with the showerhead ion filter compared to the counterpart without any ion filter, and that matches the measured spectra of OES. Meanwhile, N2(A3)—a nitrogen metastable particle crucial to the growth of III-nitrides—keeps a moderate number density and the ratio of the number density of N2(A3) to the number density of nitrogen ions was increased up to 4–5 times as the showerhead ion filter has a relatively high transmission to nitrogen metastable particles. GaN films were successfully grown with our home-made IF-ICP-MOCVD at 480 °C, which shows great potential in the epitaxy of III-nitrides at low temperature.