Method for Producing Group III Nitride Semiconductor

A method for growing Group III nitride semiconductor on a substrate made of a material different from Group III nitride semiconductor, the method comprising:

• forming a buffer layer of AlN or AlxInyGa1-x-yN (0<x<1, 0≦y<1, 0<x+y≦1) containing Al as an essential element, in a polycrystal, amorphous or polycrystal/amorphous mixed state, on the substrate;
• forming a capping layer of GaN, InuGa1-uN (0<u≦1), or AlvInwGa1-v-wN (0<v<1, 0≦w<1, 0<v+w≦1) having an Al composition ratio lower than 1/2 of that of the buffer layer on the buffer layer at a temperature lower than a temperature at which an oxide of element constituting the buffer layer is formed;
• performing heat treatment of the substrate having the buffer layer covered by the capping layer at a heat treatment temperature which is higher than a temperature at which a crystal of body semiconductor comprising Group III nitride semiconductor grows, without exposing the surface of the buffer layer;
• and
• after the heat treatment, lowering the substrate temperature to a temperature at which a crystal of the body semiconductor grows, and growing the body semiconductor on the buffer layer covered by the capping layer or the exposed buffer layer.