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

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.