HIGH DETECTIVITY INGAAS BASE INFRARED HOT-ELECTRON TRANSISTOR

An infrared hot-electron transistor with a thin (300 angstrom)InGaAs base layer is constructed. By adopting a thin base material with a large GAMMA-L valley separation, the photocurrent transfer ratio is improved by a factor of four in comparison with the GaAs base transistor. As a result, the detectivity of the transistor is increased to 1.4 X 10(10) cm square-root Hz/W at 77 K with a cutoff wavelength of 9.5-mu-m, two times as large as the companion state-of-the-art GaAs quantum well photoconductor. Combined with the lower dark current, the voltage responsivity and the noise equivalent temperature difference of a detector array can be improved by more than an order of magnitude.