GaN growth via tri-halide vapor phase epitaxy using solid source of GaCl3: investigation of the growth dependence on NH3 and additional Cl2

Gallium nitride (GaN) growth via a tri-halide vapor phase epitaxy method using a solid source of GaCl3 and gaseous NH3 was investigated both on Ga-polar and N-polar GaN templates. The relationship between gallium precursor molecule and growth polarity was clarified; it was found that a small amount of GaCl3 could be reduced by H2 originating from the decomposition of NH3 to produce GaCl, and additional Cl2 could suppress the reduction process. Accordingly, GaCl3 was found to be a proper Ga precursor for N-polar GaN growth, whereas GaCl was the proper precursor for Ga-polar GaN growth. The state of the Ga precursor molecule could be predicted by thermodynamic analysis. Furthermore, the decomposition ratio of NH3 could be determined by a combination of the experimental results and the calculated value of the thermodynamic analysis.