Noise Characteristics in Multiple Quantum Well

초록

This experiment provides both generation-recombination (GR) noise in multiple quantum well infrared photodetector (MQWIP) and shot noise in double quantum well (DQW) resonant tunnel diode (RTD). For MQWIP, GR is accepted to be a dominant mechanism of current noise source in quantum well system biased by electrical field normal to the layers.[1] At a constant bias, the quantum well system randomly switches between a high resistive state and low resistive state due to the emission and capture by the wells. We evaluated the power spectral density of GR noise which shows Lorentzian form by using low frequency noise measurement technique. For DQW RTD, we report experimental shot noise studies to probe the tunneling transport properties. The shot noise measurement show the signatures of coherent transport not only in the resonant regime but also in the plateau-like region of the current-voltage (I-V) trace on the negative differential resistance (NDR) side. The experimentally extracted Fano factor F<0.5 may suggest that the coherent transport gradually becomes obvious in the plateau-like region of NDR region due to energy level alignment by both the localization of confining potential and the coupling between energy levels for reasons of the wave function overlap as temperature goes down.[2,3] Generally, we demonstrate the characteristics of 1/f, GR and shot noise among many kinds of noise sources in quantum well structures.