Effect of emitter layer concentration on the performance of GaAs p/sup +/-i homojunction far-infrared detectors: a comparison of theory and experiment

The performance of GaAs multilayer (p/sup +/-i-p/sup +/-i-...) homojunction interfacial workfunction internal photoemission (HIWIP) far-infrared (FIR) detectors as a function of emitter layer (p/sup +/) concentration is reported. The dark current characteristics have been investigated and compared with a model which includes the space charge, tunneling, and multiple-image-force effects. The experimentally determined detector cutoff wavelength is found to be in reasonable agreement with the high density (HD) theory. The detector responsivity follows well the quantum efficiency predicted by scaling the free carrier absorption coefficient linearly with the doping concentration. All these comparisons are necessary to design and optimize GaAs HIWIP FIR detectors.