Accumulation-mode single-electron pumping in undoped GaAs*

Single-electron pumps (SEP) have demonstrated quantized charge pumping at frequencies beyond 1 GHz and temperatures up to 17 K [1]. Recently, a non-adiabatic SEP integrated with a lateral p-n junction in a direct band gap semiconductor has been proposed as a single-photon source (SPS) [2]. The SEP injects individual electrons into a 2D hole gas, forming electrically-driven excitons that recombine to emit single photons. Provided that the electron injection rate is slower than the exciton lifetime, single-photon pulses will not overlap. Undoped AlGaAs/GaAs heterostructures are a promising platform for such a SPS, as they have ultra-high mobilities, excellent reproducibility between cooldowns, and ambipolar Ohmic contacts can be fabricated [3].

We demonstrate single-electron pumping at high frequencies in accumulation-mode undoped SEPs, distinct from the depletion-mode devices typically used in doped AlGaAs/GaAs heterostructures. We discuss the advantages that this platform possesses for integration into a SPS and other applications, such as metrology. We also report on ~200 ps exciton lifetimes measured via electroluminescence in the same GaAs/AlGaAs heterostructures. These developments open a path to a bright, on-demand, all-electrical SPS with potential for scalability.