Narrow-band long-/very-long wavelength two-color type-II InAs/GaSb superlattice photodetector by changing the bias polarity

Abstract

We report on a narrow-band two-color photodetector using type-II InAs/GaSb superlattices (SLs) in the long-/very-long wavelength infrared (VLWIR) ranges by changing the polarity of the bias. The narrow-band photoresponse is achieved by sequentially growing the doped SL structure that has a shorter cutoff wavelength as a low-pass filter for the absorption layers that has a longer cutoff wavelength. At 77 K, the 50% cutoff wavelength of the photodiode is 10 μm when the applied bias voltage is –0.1 V and is 16 μm at +40 mV. The $\delta \lambda /\lambda$ is 44% for the LWIR band and is 46% for the VLWIR band.