Effects of AlN and AlGaN Interlayer on Properties of InAlN/GaN Heterostructures

InAlN/GaN heterojunction structures are grown on two-inch c-face(0001) sapphire substrates by metalorganic chemical vapour deposition. AlN and AlGaN interlayers are intentionally inserted into the structure to improve the electrical properties. The lowest sheet resistance of 359Ω/sq and the highest room-temperature two-dimensional electron gas (2DEG) mobility of 1051 cm 2 V −1 s −1 is obtained in the structure with AlN thickness of 1.3 nm. The structure with AlN thickness of 2 nm exhibits the highest 2DEG concentration of 1.84 × 10 13 cm −2 . The sample with an AlGaN interlayer gives a smoother surface morphology compared to the one using an AlN interlayer, indicating potential applications of this technique in device fabrication.