Enhanced transport properties in InAlGaN/AlN/GaN heterostructures on Si (111) substrates: The role of interface quality

We have investigated the structural and transport properties of InAlGaN/AlN/GaN heterostructures grown on Si substrates. By depositing the AlN spacer layer at a low temperature after the growth interruption, the surface morphology and interface quality have been significantly improved. Electron mobilities of 1620 cm²/Vs at room temperature and 8260 cm²/Vs at 77 K are achieved while delivering a high electron sheet density of about 2.0 × 10¹³ cm⁻², resulting in an extremely low sheet resistance of 186 Ω/□ at room temperature and 37 Ω/□ at 77 K. The experimental results evidence that it is the high interface quality that contributes to the improvement of electron transport properties. Our results provide an effective approach to obtain high quality InAlGaN/GaN heterostructures.