Interband cascade infrared photodetectors based on Ga-free InAs/InAsSb superlattice absorbers

摘要

We present an interband cascade infrared photodetector based on Ga-free type-II superlattice absorbers. Substituting the more standard InAs/GaSb superlattice for a Ga-free superlattice with InAs/InAsSb requires an inverted carrier extraction path. A hole-ladder in the electron-barrier, instead of an electron-ladder in the hole-barrier, is employed to achieve photovoltaic operation. At elevated temperatures, seven negative-differential-conductance (NDC) regions are observed that arise from electrons tunneling through the electron barriers of the seven cascade stages. The detector operates in the photovoltaic mode at room temperature with a cutoff wavelength of 8.5 μm. At the NDC regions, the device features responsivity peaks under laser illumination reaching 0.45 A/W at room temperature at λ = 5.27 μm. This exceeds its highest measured low-temperature value of 0.22 A/W at this wavelength by a factor of 2.