Large-Diameter GaN Substrates with HCl-Controlled Mn Uniformity

The patent applies periodic action by intermittently introducing HCl gas during the epitaxial growth process. The HCl gas is introduced at specific time intervals to etch the growth interface, creating periodic cycles of growth and etching. This periodic etching prevents Mn accumulation at the interface and ensures uniform Mn concentration distribution across the large-diameter substrate while maintaining high resistivity.

The patent changes the chemical environment parameter by introducing HCl gas into the growth chamber during epitaxial growth. This parameter change modifies the chemical composition at the growth interface, enabling controlled etching that prevents Mn concentration variations. The HCl gas concentration and introduction timing are controlled to achieve uniform doping across the substrate.

The patent implements periodic action by introducing HCl gas at predetermined time intervals rather than continuously. The HCl gas is introduced for specific durations followed by growth periods, creating a cyclic process. This periodic introduction achieves sufficient etching for Mn uniformity while minimizing interruption to the overall epitaxial growth process, thereby balancing quality and productivity.

The patent applies preliminary action by introducing HCl gas before Mn doping is complete to pre-etch the growth interface. This preliminary etching prevents Mn concentration buildup during subsequent growth periods, ensuring uniform distribution without requiring continuous HCl introduction throughout the entire growth process.