Impact ionization in THz QWIPs

Recently phase transitions in THz Quantum Wells Inter-subband Photodetectors (QWIP) were observed. Very large current discontinuities - up to five orders of magnitude - were obtained, at low temperature
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. Quantum well impact ionization shifts the structure from a resistive “down” state, where the current flows through inter-well quantum tunneling to a highly conductive “up” state. In this paper, thanks to the analysis of the bias versus current “s” curve, an accurate investigation of impact ionization processes in quantum wells is analyzed. The use of these phenomena for high sensitivity quantum well THz detection will be presented.