Bias effects in high performance GaAs homojunction far infrared detectors

W. Z. Shen, A. G. U. Perera
Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303

H. C. Liu, M. Buchanan
Institute for Microstructural Sciences, National Research Council,
Ottawa K1A 0R6, Canada

W. J. Schaff
School of Electrical Engineering, Cornell University,
Ithaca, NY 14853

ABSTRACT
A high performance, bias tunable, p-GaAs homojunction interfacial workfunction internal photoemission (HIWIP) far-infrared (FIR) detector has been demonstrated. A responsivity of 3.10 A/W, a quantum efficiency of 12.5 \% and a detectivity D* of 5.9 x 10^{10} cm Hz^{1/2} /W, were obtained at 4.2K, for cutoff wavelengths from 80 to 100 microns. The bias dependences of quantum efficiency, detectivity, and cutoff wavelength have been measured and are well explained by the theoretical model. The effect of the layer number on detector performance and the uniformity of the detectors have been discussed. A comparison with Ge:Ga photoconductive detectors suggests that a similar or even better performance may be obtainable.