Intersubband impact ionization in THz QWIPs: shaping band structure reorganizations to design novel detectors

Electronic transport in AlGaAs/GaAs THz Quantum Wells Intersubband Photodetectors (QWIPs) exhibits two different regimes separated by huge discontinuities (up to five orders of magnitude) in the resistivity. They are interpreted in terms of band structure reorganizations triggered by intersubband impact ionization. We will analyze and model their in uence on the electronic transport. The magnitude of the transport modifications is explained by the small transition energy and the sharpness of the electrons distribution at stake in THz QWIPs. Measurements under magnetic field or temperature show that the broadening of the electron distribution damps the effects of impact ionization. Some experimental features of the electronic transport of shorter wavelength detectors are then reproduced. The use of intersubband impact ionization in THz QWIPs to design high gain and fast novel detectors is discussed.

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