Near- and far-infrared p-GaAs dual-band detector

Abstract

A dual-band homojunction interfacial workfunction internal photoemission infrared detector that responds in both near- and far-infrared (NIR and FIR) regions is reported. In the p+-i-p+ detector structure, the emitter is carbon doped to 1.5×1019cm−3, and a 1μm thick GaAs layer acts as the barrier, followed by another highly p-doped GaAs contact layer. The NIR response is due to the interband transition in GaAs barrier layer and the threshold wavelength observed at 0.82μm is in good agreement with the 1.51eV band gap of GaAs at 4.2K. The intraband transition giving rise to FIR response is observed up to 70μm. Interband responsivity was (under 100mV reverse bias at 20K) ∼8A∕W at 0.8μm, while the intraband responsivity was ∼7A∕W. The detector has peak detectivities D*∼6×109 and 5×109cmHz1∕2∕W at 0.8 and 57μm wavelengths, respectively, under 100mV reverse bias at 20K.