Prediction of inverse spin Hall devices based on the direct injection of carriers in L-valley of GaAs

Abstract

Numerical simulations are carried out to estimate the inverse spin Hall voltage (V ISHE) as a function of applied electric field, dopant density and excitation energy for n-GaAs based opto-spintronic devices. Adopting a three valley rate equation model, an expression is derived for the density of spin polarized electrons accumulated in different valleys of conduction band. It is noted that an external electric field can be used to enhance the magnitude of V ISHE significantly, however the shape of curve depends upon the choice of excitation energy. A significant rise of V ISHE is noted beyond a critical value of electric field when the carriers are injected into Γ-valley of GaAs. On the other hand, a peak like behaviour is observed when hot electrons are injected into Γ-valley. A dual slope behaviour of V ISHE with applied electric field is noticed when carriers are injected directly into L-valley of GaAs, where a reasonable value of V ISHE can be predicted even for a modest value of electric field. Further, a peak like behaviour of V ISHE with dopant density is predicted irrespective of the choice of excitation energy. The optimum dopant density of n-GaAs based Inverse spin Hall devices is found to be ∼4 × 1016 cm−3. Theoretical predictions made in this work are critically important for the realization of next generation inverse spin Hall devices involving L-valley electrons.