A. G. U. Perera
Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303
Silicon, the second most abundant material in the earth's crust, (>25% in mass) became the most widely used semiconductor material within a relatively short time, replacing germanium which was the first semiconductor material to be studied. As the industry matured, it became the favorite material for integrated circuits. Similar to silicon for electronics, where control of the flow of electrons is the game, GaAs plays a major role in photonics where the concentration is on the photons. The direct bandgap of GaAs makes these photonic devices both much better than Si devices and efficient photon emitters. Combining electronic and photonic devices creates optoelectronics. A photon absorption can give rise to an electron-hole pair production, while photon emission is due to electron-hole recombination. Hence, the generation or the recombination of an electron-hole pair is fundamental to the operation of intrinsic optoelectronic devices. Although this volume is on optoelectronic materials, teh focus here is only on detector material, specifically in the far-infrared (FIR) wavelength range. As another chapter in this volume concentrates on photoconductors, emphasis here is on a novel FIR detector approach, which in principle, can be used with any semiconductor material. However, the discussion will be limited to Si and GaAs FIR detectors that have already been demonstrated, and on improvements (increased absorption and reduced dark current) to make the detectors better suited for astronomical applications.
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