Long room-temperature electron spin lifetimes in bulk cubic GaN

Abstract

We report on very long electron spin lifetimes in cubic GaN measured by time-resolved Kerr-rotation-spectroscopy. The spin coherence times with and without external magnetic field exceed 500 ps at room temperature, despite a high n-type doping level of more than 10 19 cm -3 in the bulk sample under investigation. Our findings are therefore highly relevant for spin optoelectronics in the blue wavelength regime. The spin lifetimes are found to be almost temperature independent in accord with a prediction for degenerate electron gases of Dyakonov and Perel from 1972. These results are discussed also in comparison to wurtzite GaN, which shows much shorter spin lifetimes and a dependence of spin lifetimes on the spin orientation.