Band-edge-emphasizing photodetector response

A photodetector having a sensitivity only in a narrow-wavelength region has been fabricated by utilizing a thick semi-insulating GaAs (SI GaAs). Because the photon energy at the peak response is nearly equal to the bandgap energy of GaAs, this detector is called a band-edge-emphasizing photodetector. A theory is proposed to explain this phenomenon. Since GaAs is characterized by a short carrier lifetime and a steep change of the absorption coefficient, the active layer is assumed to be composed of two different parts connected in series, which are specified by a function delta . Good agreement has been shown between the experimental and the theoretical results on the sensitivity characteristics. >