Dependence of Polarity and Crystal Quality of the HVPE GaN Buffer Layers on the Surface Treatment of Substrates (GaAs and Sapphire)

Abstract

To investigate crystal quality and polarity of the buffer layer grown by the halide vapor phase epitaxy (HVPE), buffer layers were grown both on GaAs (111) and on sapphire substrates. The buffer layer grown on the GaAs(111) substrate pre-treated with GaCl was high quality with Ga polarity, but only an amorphous GaN buffer could be deposited on the sapphire substrate pre-treated with GaCl. The buffer layer grown on a nitridated sapphire substrate was crystallized with c-axis oriented but it aggregated by annealing at 1000 °C and polarity could not be determined. However, GaN grown at high temperatures on the nitridated sapphire substrate gave Ga polarity.