Wave Propagation In Dielectrics Research Articles

Observation of resonant tunneling through localized continuum states in electron wave interference diodes

A 13 layer aperiodic semiconductor superlattice electron wave interference filter, designed with thin-film optical interference filter techniques by using the analogies between electromagnetic wave propagation in dielectrics and ballistic electron wave propagation in semiconductors, was realized in the GaAs/AlGaAs material system. Current-voltage measurements at 300 and 77 K show negative differential resistance peaks (with peak-to-valley current ratios of 1.25 and 3.9, respectively) that represent observation of tunneling through an above barrier localized quasibound state. We show that electron wave interference devices could compete with resonant tunneling diodes as high frequency oscillators based on dc device characteristics and theoretical subpicosecond tunneling traversal times.

Semiconductor superlattice interference filter design

The quantitative analogies that have been previously established [J. Appl. Phys. 65, 814 (1989)] between electron wave propagation in semiconductors and optical wave propagation in dielectrics may be used to translate thin-film optical device designs into semiconductor superlattice device designs. The procedure for this direct mapping is also described in the above reference. The resulting designs, however, have compositions that are not constrained to be within a usable compositional range and they have layer thicknesses that are not constrained to be integer multiples of a monolayer thickness. In the present work, a systematic design procedure is presented that includes these required practical constraints. This procedure is then applied to the design of Ga1−xAlxAs superlattice narrow interference filters. For pass kinetic energies in the range of 0.14–0.20 eV, compositions (values of x) and numbers of monolayer thicknesses needed to produce quarter-wavelength layers are calculated. The detailed design of an example narrow bandpass (15.4 meV) filter with a pass electron energy of 0.20 eV is presented.

Semiconductor superlattice electron wave interference filters

The quantitative analogies that have been established between electron wave propagation in semiconductors and optical wave propagation in dielectrics are used to demonstrate that high-resolution energy filters in semiconductors are possible. An example filter consisting of electron quarter-wavelength layers of GaAs and Ga0.55Al0.45As and a half-wavelength layer of GaAs is presented and theoretically analyzed. The pass electron energy is 0.139 eV and the passband is only 0.003 eV (2.2% of pass energy). Such a filter could be incorporated into semiconductor devices (e.g., as a hot-electron emitter in a ballistic transistor) or used to control free-space electron beams (e.g., in electron beam lithography).