Highly sensitive, photon number resolving detectors mediated by phonons using delta-doped GaAs transistors.

We report a photon number-resolving detector using two-dimensional electron gas (2DEG)-based transistors. When the photon pulses impinge on the absorption region, the generated phonons dissipate ballistically in the 2DEG toward the trench isolated nanowire transistors near the surface. The phonon-electron interaction induces a positive conductance in the transistors, resulting in a current increase. With this principle, we obtain an internal quantum efficiency for this type of detector of up to 85%.