GaAs multilayer p(+)-i homojunction far-infrared detectors

A molecular beam epitaxy grown wavelength tunable GaAs p(+)-i homojunction interfacial work-function internal photoemission far-infrared detector is developed. The multilayer (p(+)-i-p(+)-i-...) detector structures consist of 2, 5, and 10 emitter layers. Experimental results are explained in terms of the number of emitter layers and the doping concentrations of the emitter layer. A detector with 10 multilayers and an emitter layer doping concentration (N-e) of 3 x 10(18) cm(-3) shows a current responsivity of 2 A/W, an effective quantum efficiency of 9.2% (at 26.3 mu m) with a cutoff wavelength of 85 mu m and the noise equivalent power of 2.18 x 10(-12) W/root Hz at 4.2 K. (C) 1997 American Institute of Physics.