Long Wavelength Type II InAs/GaSb Superlattice Photodetector Using Resonant Tunneling Diode Structure

Abstract

We report on a long wavelength type-II InAs/GaSb superlattice photodetector using resonant tunneling diode (RTD) structure. The linewidth of the satellite peak of the x-ray diffraction curve of the as-grown sample is only 15.7 arcsec showing a very high structural quality. The response maximum wavelength of the RTD detector is $7.5~\mu \text{m}$ and the 50% cutoff wavelength is $9.6~\mu \text{m}$ at 77 K. The measured QE is 147% at $7.5~\mu \text{m}$ when the applied bias voltage is 1.45 V and the corresponding responsivity is 8.9 A/W. This unusual QE is attributed to a large gain achieved when the device is under a resonant tunneling condition. The corresponding shot noise limited detectivity D* is $1.2\times 10^{10}\text {cm}\cdot \sqrt {Hz}/W$ at 1.45 V at 77 K.