Electronic transport in a long wavelength infrared quantum cascade detector under dark condition

• A two-stage performance of dark current in quantum cascade detectors is proposed.
• Magneto-transport experiment is performed and magnetophonon resonance is observed.
• The dominant transition contributing to the dark current is figured out.

We present a joint experimental and theoretical investigation on a long wavelength infrared quantum cascade detector to reveal its dark current paths. The temperature dependence of the dark current is measured. It is shown that there are two different transport mechanisms, namely resonant tunneling at low temperatures and thermal excitation at higher temperature, dominate the carrier flow, respectively. Moreover, the experimental intersubband transition energies obtained by the magneto-transport measurements matches the theoretical predictions well. With the aid of the calculated band structures, we can explain the observed oscillation phenomena of the dark current under the magnetic field very well. The obtained results provide insight into the transport properties of quantum cascade detectors thus providing a useful tool for device optimization.