SHOT-NOISE IN RESONANT-TUNNELING STRUCTURES

We propose a quantum-mechanical approach to noise in resonant-tunnelin g structures that can be applied in the whole range of transport regim es, from completely coherent to completely incoherent. In both limitin g cases, well-known results which have appeared in the literature are recovered. Shot noise reduction due to both Pauli exclusion and Coulom b repulsion, and their combined effect, are studied as a function of t he rate of incoherent processes in the well (which are taken into acco unt by means of a phenomenological relaxation time), and of temperatur e. Our approach allows the study of noise in a variety of operating co nditions (i.e., equilibrium, subpeak voltages, second-resonance voltag es), and as a function of temperature, explaining experimental results and predicting interesting results, such as the dependence of noise o n filled-emitter states and the prediction of both increasing and decr easing shot noise with increasing temperature, depending on the struct ure. It also allows the determination of the major contributions to sh ot-noise suppression by performing noise measurements at the second-re sonance voltage.