Abstract
We report the observation of a new type of helicity-dependent photocurrent induced by an in-plane transverse direct electric current in an InAs quantum well. The amplitude of the photocurrent depends linearly on the transverse current. Moreover, the observed incident azimuth-angle dependence of this photocurrent is different from that induced by the circular photogalvanic effect. This new photocurrent appears as a result of an asymmetrical carrier distribution in both the conduction and valence bands induced by the transverse current. The photoexcited carrier density created by interband transition processes is thus modulated and leads to the observed new azimuth-angle dependence. The observed efficient generation of the helicity-dependent photocurrent offers an effective approach to manipulate electron spins in two-dimensional semiconductor systems with the added advantage of electrical control of the spin-related photocurrent in spintronic applications.
Highlights
Polarised light is passed through a rotatable quarter-wave plate, so that the sample is illuminated using elliptically polarised light with a circular polarisation degree defined by Pcirc = sin2φ, where φ is the angle between the polarisation plane of the laser radiation and the optical axis of the quarter-wave plate
We mainly focus on the helicity-dependent photocurrent (HDPC) component, which is the photocurrent induced by the circular photogalvanic effect (CPGE) when there is no transverse current applied
As the CPGE photocurrent has a cos(β) dependence, the component of the DC-induced HDPC can be considered as a modulation of the CPGE photocurrent by the transverse current
Summary
The HDPC is first measured by varying the amplitude of the transverse current with the orientation of the incident plane of the excitation laser beam fixed at β = 0° (the orientation of the incident plane of excitation laser beam relative to the direction of the applied in-plane direct current is defined as the incident azimuth angle β) [Fig. 1(b)]. To investigate further the effect of the transverse current on the HDPC, the dependence on incident azimuth angle (referred to as the β dependence) of the HDPC driven by different transverse currents is measured [Fig. 4(a); the CPGE-induced photocurrent has been subtracted]. As the CPGE photocurrent has a cos(β) dependence, the component of the DC-induced HDPC can be considered as a modulation of the CPGE photocurrent by the transverse current
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