Patent ID: 8878189

Claim:
A Group III nitride semiconductor growth substrate comprising: a crystal growth substrate including a surface portion composed of Al x Ga 1-x N (0.5≦x≦1), a surface of the surface portion having a crystal orientation of the {0001} plane, a scandium nitride film formed on the surface of the surface portion, and having a crystal orientation of the {111} plane, and an initial growth layer formed on the scandium nitride film, at least having a first buffer layer made of Al y Ga 1-y N (0≦y≦1) directly on the scandium nitride film and a second buffer layer made of Al z Ga 1-z N (0≦z≦1) directly on the first buffer layer, wherein the first buffer layer is formed at a growth temperature in a range of 900° C. to 1260° C. and the second buffer layer is formed at a growth temperature in a range of 1030° C. to 1300° C., and wherein the growth temperature of the first buffer layer is lower than the growth temperature of the second buffer layer, wherein the first buffer layer is composed of AlN and the second buffer layer is composed of AlN.