Quadrupolar photovoltaic effect in the terahertz range in a two-dimensional spin-3/2 hole system

TL;DR

This paper reports a strong, tunable quadrupolar photovoltaic effect in a two-dimensional spin-3/2 hole system, which could enable terahertz detection based on non-linear optical transitions between heavy and light hole sub-bands.

Contribution

It introduces the quadrupolar photovoltaic effect (QPE) in 2D spin-3/2 hole systems and explores its potential for terahertz photodetectors, highlighting the role of T_d-symmetry and resonance near hole splitting.

Findings

Photovoltaic current shows a strong resonance near heavy-light hole splitting.

The magnitude of the effect is governed by the momentum relaxation time, reaching nanoseconds.

QPE can be tuned by adjusting the heavy hole-light hole splitting from a few meV to 100 meV.

Abstract

We identify a strong photovoltaic response due to the non-linear optical transition between heavy and light hole sub-bands enabled by T_d-symmetry in a quantum well, which we term the quadrupolar photovoltaic effect (QPE). The photovoltaic current exhibits a strong resonance in the vicinity of the heavy hole-light hole splitting, with a magnitude governed by the momentum relaxation time, which can reach nanoseconds in GaAs holes. Since the heavy hole-light hole splitting can be tuned from a few meV to nearly 100 meV the QPE could serve as the basis for a terahertz photo-detector. We discuss strategies for experimental observation and device applications.