A Novel SiGe Heterojunction Phototransistor Applicable in Wide Spectral Range

This paper reports on a novel SiGe heterojunction phototransistor (HPT) with a wide applicable spectral range covering 405–940 nm wavelength. By introducing the Ge component into the base region and designing its content and distribution, the absorption band and applicable spectral range are greatly broadened. Under the illumination of a light source with
$14.3\ \mu \mathrm{W}$
optical power, the responsivity of HPT is 1.72 A/W, 12.38 A/W, 3.69 A/W, and 0.77 A/W at 405 nm, 650 nm, 850 nm, and 940 nm wavelength respectively.