Wavelength-extended photovoltaic infrared photodetectors.

We report the incorporation of a long-wavelength photovoltaic response (up to 8 μm) in a short-wavelength p-type GaAs heterojunction detector (with the activation energy of EA s 0.40 eV), operating at 80K. This wavelength-extended photovoltaic response is enabled by employing a non-symmetrical band alignment. The specific detectivity at 5 μm is obtained to be 3.5c1012 cm Hz1/2/W, an improvement by a factor of 105 over the detector without the wavelength extension. [ABSTRACT FROM AUTHOR]