| abstract |
A method of manufacturing a substrate capable of improving the crystallinity of a crystal layer of a group III nitride semiconductor is provided. A sapphire single crystal having an upper surface of (0001) is used as a base substrate, a chromium layer is formed on the top surface of the base substrate, and then the base substrate on which the chromium layer is formed is used to grow a GaN crystal. The chromium nitride (CrN) film is formed by carrying out heat nitriding treatment at a temperature of 1000 ° C. or higher in a reducing gas atmosphere containing nitrogen, and at this time, the intermediate layer containing aluminum nitride is It is formed between the base substrate and the chromium nitride film. Next, after forming the GaN buffer layer, the substrate temperature is raised to 1040 ° C., and a GaN crystal layer is grown, thereby obtaining a GaN single crystal substrate having a pit density on the upper surface of 105 / cm 2 or less. It is done. If necessary, the chrome nitride film is selectively etched to separate the GaN substrate from the underlying substrate. [Selection] Figure 15 |