Spin relaxation induced by interfacial effects in GaN/Al0.25Ga0.75N heterostructures

Abstract

Spin relaxation induced by the interfacial effects in GaN/Al0.25Ga0.75N heterostructures was carefully investigated using a photon-energy-dependent time-resolved Kerr rotation spectrum. The existence of the interfacial localized states with potential fluctuations at the GaN/AlGaN heterointerface leads to photoluminescence peaks showing blue and S-shaped shifts owing to the excitation power and temperature, respectively. Photoexcited electrons in the localized states show a spin relaxation time longer than 1 ns because of the suppression of the D'yakonov–Perel’ (DP) scattering, while the spin relaxation time of free electrons was approximately only 10 ps because of the giant Rashba spin-orbit coupling induced by the interfacial polarization field under the framework of the DP scattering mechanism. Furthermore, it is found that the high electron mobility at the heterointerface results in a long spin diffusion length of 300 nm at high temperatures, which is promising for the development of GaN-based spintronic devices.

Keywords

• GaN/AlGaN heterointerface
• Two-dimensional electron gas
• Interfacial localized state
• Spin dynamics
• Polarization field