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Simulation of negative-effective-mass terahertz oscillators

“…13, which are completely determined by p d ,T h , and ͑or n͒ for a semiconductor system with known impurity distributions, phonon modes, electron-impurity potentials, and electron-phonon coupling matrix elements. Following the treatments of Vagidov et al, [8][9][10][11] in the present model calculation of the hole transport we assume a three dimensional ͑3D͒ dispersion of hole gases as follows: 9…”

“…[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.…”

“…The oscillating frequency lies in the THz range for the NEM oscillators with submicrometer base lengths. It is believed [8][9][10][11] that if the p-base thickness l is short enough for hole transport without scattering by optical phonons, the collisionless Boltzmann equation may give a reasonable description of ballistic process of the holes. In the case of materials such as p-InAs and p-InGaAs, stricter condition lϽ0.05-0.06 m must be satisfied for maintaining ballistic transport across the base, but in the submicrometer range of the base length scatterings should be important for hole transport.…”

Ballistic field-effect transistor with negative-effective-mass current carriers in the channel

“…1. The presented dispersion relation relates to quantized holes of the ground quantization subband for a square 8 nm p-type GaAs/AlAs quantum well (see details in [8]). These holes are selected here as current carriers in the channel of the calculated FET.…”

“…In the y-direction, periodicity conditions (with spatial period 2a = 0.16 µm) are used as boundary conditions. It is shown [8] that such a period value allows us to consider parallel current-conducting channels as almost independent devices. Calculations are carried out for AlAs-barrier medium (with the dielectric constant κ D = 10.9) at a temperature of 4.2 K. Because of the assumed lack of current carriers outside the channel we have no stationary current in the gate.…”