Terahertz ballistic current oscillations for carriers with negative effective mass

Abstract

It is shown that the stationary distribution of ballistic current carriers moving across a thin doped base is unstable if there exists a negative effective mass (NEM) part in the carrier dispersion law. Under such a condition, a regime with a quasistationary current oscillations is established for a wide range of voltages across ballistic diode. The oscillation frequency and amplitude depend on the base length, doping concentration, and applied voltage. The current oscillations take place in a short-circuit regime (in absence of an external resonator). We consider asymmetric double quantum wells and/or composite ΓX quantum wells as possible structures allowing for the required dispersion relation with NEM part. Carrier dynamics in these structures are described quasiclassically and the validity of such a treatment is discussed.

Simulation of negative-effective-mass terahertz oscillators

“…[3][4][5][6] Most recently, two designs of the ballistic terahertz ͑THz͒ generators based on the nonparabolic NEM hole dispersion have been suggested. 7 Theoretically, using a model hole dispersion relation with a NEM region, Vagidov et al [8][9][10][11] carried out a series of calculations of hole ballistic transport in thin p ϩ pp ϩ doped diodes by using the Poisson equation and the collisionless Boltzmann equation. It is indicated, under certain biases, sta-tionary concentration distributions of the ballistic holes in p ϩ pp ϩ structures hold a self-organized region where holes with NEM predominate.…”

Effect of contacts on terahertz plasma resonances in two-dimensional electron systems

“…To solve (1) with the boundary conditions (5), we adapted the numerical procedure called the splitting scheme [8], [9] (we used the cubic spline method for interpolations required in the method). The method allows to solve the Vlasov equation with the numerical accuracy of the order of Δt 2 , where Δt is the time step for the numerical simulation.…”

EnergyDispersion Relations for Holes in Silicon Quantum Wells and Quantum Wires

“…In addition, the carried out calculations showed that the Kramers degeneracy [6] of holes at k 2D || [110] is lifted for k 2D = 0 and there are two different branches of dispersion (4,5,6) lines correspond to holes with opposite spins relations corresponding to two different spin states as it is seen in Fig. 2 [7].…”

“…(1), may have self-organized oscillatory regimes only at certain ratio of two effective masses, m and M, -light and heavy effective masses, respectively. This ratio must satisfy the following inequality [5]:…”