Observation of a negative differential resistance due to tunneling through a single barrier into a quantum well

Abstract

We have observed a negative differential resistance (NDR) in a single-barrier tunneling structure in which electrons tunnel from a doped semiconductor emitter layer into a quantum well (QW) layer and subsequently drift laterally to a specially designed contact. Pronounced NDR is seen already at room temperature and at 77 K the peak to valley (PTV) ratio in current is more than 2:1. Our results lend support to a recent hypothesis by Luryi [Appl. Phys. Lett. 47, 490 (1985)] that the NDR in double-barrier tunneling structures is not related to a resonant enhancement of the tunneling probability at selected electron energies, but rather originates from tunneling into a system of electron states of reduced dimensionality. For comparison we have also fabricated a QW structure with two tunneling barriers, in which the parameters of the emitter barrier and the QW are identical to those in the single-barrier structure. In the double-barrier structure we have obtained current densities as high as 4×104 A/cm2 and a NDR with PTV ratios of 3:1 at 300 K and 9:1 at 77 K.

Shot noise in negative-differential-conductance devices

“…Simple noise measurements like those presented here should be able to discern between competing transport mechanisms in other mesoscopic structures in which charge accumulation is an issue, even as subtle as in the case of tunneling through a single barrier into a quantum well. 13 Such measurements might also help to differentiate between sequential and coherent tunneling in multple-well heterostructures.…”

Resonant tunneling through single GaAlAs barriers

“…2, place Jussieu, F-75251 Paris Cedex, France. nances through a single tunneling barrier into a quantum well was recognized as such in [9], a clear observation of enough oscillations in the I-V characteristics allowing to fit the data with the theory is still missing.…”

“…This allowed us t,o precise the field and temperature ranges in which they can be observed and to look for the role of electron scattering. We shall see that electron scattering by residual defect,s is so low that oscillations are clearly seen up to 120 K, like in the case where an adjacent quantum well is used [9] and like in the case of Si/SiOz structures [a, 31. We finally studied the effect of the presence of additional defects in the barrier, defects that are introduced in a controlled fashion by electron irradiation.…”

Observation of negative differential transconductance in tunneling emitter bipolar transistors

“…[2][3][4][5] The fundamental origin is the appearance of bias dependent states into which charge carriers can tunnel. Much attention has been devoted to this phenomenon because of the promise it holds to realize high-frequency oscillators.…”