Two dimensional electron gas in InN-based heterostructures: Effects of spontaneous and piezoelectric polarization

Abstract

This paper predicts and describes the formation of two dimensional electron gas (2DEG) in InN-based heterostructures, as a promising candidate for future high performance high electron mobility transistor (HEMT). The effects of spontaneous and piezoelectric polarization on carrier confinement and localization of 2DEGs have been studied. These include the theoretical analysis and calculation of spontaneous and piezoelectric polarization, and polarization induced sheet charge bound at the interfaces of InN/InGa(Al)N/InN heterostructures as a function of lattice mismatch induced strain. Significant effects of polarity are found on carrier confinement and localization of 2DEGs. A high sheet carrier concentration and strong electron confinement at specific interfaces of the InN-based heterostructures are predicted as a consequence of piezoelectric and spontaneous polarization effects. The calculated sheet carrier concentration reaches as high as 2.12 × 10 14 and 7.08 × 10 13 cm −2 for AlN and GaN barriers, respectively. These sheet carriers generated in InN-based heterostructures are higher than the reported values for the conventional GaN-based AlGaN/GaN HEMTs. The accumulation of electrons can be confirmed for a barrier thickness of above 4 nm.