OBSERVATION OF TELEGRAPH NOISE IN THE REVERSE PHOTOCAPACITANCE, PHOTOCURRENT, AND FORWARD DARK CURRENT OF A QUANTUM-WELL DIODE

We report measurements on transport perpendicular to a single quantum well located on the n side of a p-n junction in a InP/InGaAs device. Zero-bias admittance spectroscopy and photocapacitance transient measurements are used to characterize electron and hole emission rates. Both rates show a crossover from a thermally activated regime to a regime of weak temperature dependence. The barrier dimensions for electron and hole emission preclude direct tunneling so that, in the low-temperature regime, transport must be defect assisted. In this regime we observe discrete fluctuations in the reverse-bias photocapacitance and photocurrent and in the forward-bias dark current. The results are explained with a model in which transport of electrons in or out of the well is regulated by the occupancy of a single electron trap associated with a defect.