Demonstration of Si homojunction photoconductors\\ for far-infrared detection

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

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

M. O. Tanner and K. L. Wang
Department of Electrical Engineering,
University of California at Los Angeles,
Los Angeles, CA 90095

ABSTRACT
A 48 micron cutoff wavelength Si far-infrared (FIR) detector is demonstrated. Internal photoemission over a Si interfacial work-function of a homojunction consisting of molecular beam epitaxy grown multilayers (p^+ emitter layers and intrinsic layers) is employed. The detector shows high responsivity over a wide wavelength range with a peak responsivity of 12.3 (0.1) A/W at 27.5 micron and detectivity D^* of 6.6 x 10^10 cm Hz^ {1/2} /W. The cutoff wavelength and bias dependent quantum efficiency agree well with theory. Based on the experimental results and the model, Si FIR detectors (40 to 200 micron) with high performance and tailorable cutoff can be realized using higher emitter layer doping concentrations.