Optimization of parameters for generating nitrogen plasma in plasma-assisted MOCVD growth of InGaN thin films

Pepen Arifin,Sugianto Sugianto,Heri Sutanto,Agus Subagio,Muhammad A Mustajab

doi:10.1063/1.5126943

Abstract

The deposition of InGaN thin films by plasma-assisted metalorganic chemical vapor deposition is achieved using nitrogen plasma as a nitrogen source. The generation of nitrogen plasma is optimized using optical emission spectroscopy, and the plasma is dominated by excited molecular nitrogen, which emits in the range 300–420 nm. The emission intensity of the plasma significantly depends on the flow rate of nitrogen gas and heater temperature and are optimally 70 SCCM and 650 °C, respectively. A further increase in these parameters results in a decrease in the intensity of the nitrogen plasma emission. An optimal flow rate and heater temperature are used to grow InGaN thin films on c-sapphire substrates. InGaN thin films grown with a TMIn vapor concentration (xv) of 0%, 50%, and 100% at a growth temperature of 650 °C are highly oriented to the (0002) plane in a hexagonal structure. The film grown with a vapor concentration of 50% has an indium concentration of 55% and no indication of phase separation. Increasing the growth temperature above 650 °C results in a decrease in the growth rate.

Highlights

The growth of GaN and its alloys by metalorganic chemical vapor deposition (MOCVD) is challenging because the molecular nitrogen used as a nitrogen source is inert at normal growth temperatures
An ECR plasma source has been successfully employed to produce reactive nitrogen species that react with TMGa and/or TMIn at substantially low substrate temperatures during the growth of InGaN by plasma-assisted MOCVD
The emission intensity of the plasma relates to the population of generated reactive nitrogen species and depends significantly on the substrate temperature and flow rate of the nitrogen gas

Summary

INTRODUCTION

The growth of GaN and its alloys by metalorganic chemical vapor deposition (MOCVD) is challenging because the molecular nitrogen used as a nitrogen source is inert at normal growth temperatures. Growth of InGaN thin films by MOCVD is challenging if a high concentration of indium is required in ternary alloys. Several investigations of nitrogen plasma using OES have focused on the identification of the active species produced by several plasma generator sources and on the growth of group IIInitrides using RF-plasma-assisted MBE growth. Since MBE growth requires high vacuum, the use of nitrogen to generate reactive nitrogen species most often involves low flow rates of nitrogen gas, typically around 1 SCCM–5 SCCM.. The characteristics of nitrogen plasma produced at high nitrogen flow rates are important for a better understanding of plasma-assisted MOCVD growth of group III-nitrides. We investigate the growth characteristics of InGaN for various flow rates of nitrogen gas, growth temperatures, and indium compositions

EXPERIMENTAL DETAILS

Plasma-assisted MOCVD growth of InGaN

OES measurement

Growth of InGaN

CONCLUSION