Role of Hot Electrons in the Development of GaAs-Based Spin Hall Devices with Low Power Consumption

Strong inverse spin Hall effect (ISHE) signal can be realized in GaAs via the electrical injection of hot electrons. In a recent article, it was demonstrated that optically induced hot electrons can also lead to the establishment of ISHE in GaAs but at much lower electric field. Herein, the combined role of high electric field and high energy optical injection of hot electrons in GaAs is examined. An anomalous behavior of ISHE voltage (V-ISHE) is observed. Spin-polarized hot-electrons are optically injected in the conduction band of n-GaAs which are then transferred from Gamma to L valley with or without applied bias. At 2.33 eV excitation energy (E-ex), a monotonous increase in V-ISHE is seen with electric field which starts to fall beyond a critical electric field. A theoretical framework based on the rate equations governing intervalley scattering is proposed, which successfully explains the observed behavior. Utilizing optically injected hot electrons at E-ex = 2.33 eV, a spin Hall device is demonstrated, that consumes less power and yields better signal-to-noise ratio. These findings are highly encouraging for the development of next-generation spin-optoelectronic devices.