High responsivity quantum cascade detectors with bound-to-miniband diagonal transition

We demonstrate a long-wavelength infrared quantum cascade detector (QCD) that operates at a wavelength of 10 μm, in which the active diagonal transition for the electrons occurs from a fundamental energy level into a miniband in adjacent coupled quantum wells. When compared with a bound-to-bound diagonal transition-based QCD, the use of a miniband as the final transition state increases the absorption strength and enhances the electron extraction efficiency of the device, leading to QCD responsivities of 75 at 180 and 30 mA/W at 300 K for 10.55 μm wavelength operation.