Improved electrical properties in AlGaN∕GaN heterostructures using AlN∕GaN superlattice as a quasi-AlGaN barrier

The authors report the electrical properties of two-dimensional electron gas (2DEG) in AlGaN∕GaN heterostructures using AlN∕GaN superlattices working as a quasi-AlGaN barrier layer. It is found that the electrical properties (2DEG mobility and sheet carrier density) in the quasi-AlGaN∕GaN heterostructure are greatly improved compared to those in the conventional alloy-AlGaN∕GaN one at the high Al composition more than 0.35. The improved 2DEG properties result in the reduction of the sheet resistance to as low as 172Ω∕□, which is extremely important for the high power and high frequency device application. Theoretical calculations clearly indicate that the quasi-AlGaN barrier plays an important role in enhancing the confinement of the carrier at the quasi-AlGaN∕GaN interface.