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

Abstract

The performance of GaAs multilayer (p +-i-p +-i-.. .) homojunction interfacial workfunction internal photoemission (HIWIP) far-infrared (FIR) detectors as a function of emitter layer (p +) 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.

Evidence for the formation of GaAs homojunction far-infrared detection by magnetic field dependent Hall analysis

“…The internal photoemission operation is that electrons are photoexcited from the emitter layers into the intrinsic layers. We have demonstrated [25] that the cutoff wavelength of the actual FIR response of GaAs device structures can be described well by the modelled band structure for the interfacial barrier height with respect to the Fermi level (it mainly depends on the doping concentration of the emitter layers and the applied bias). With increasing temperature, the Fermi level gradually moves downwards below the conduction band of the emitter layers (figure 7(b)).…”