We calculate the energy dispersion relations in Si quantum wells (QW), E(k2D), and quantum wires (QWR), E(k1D), focusing on the regions with negative effective mass (NEM) in the valence band. The existence of such NEM regions is a necessary condition for the current oscillations in ballistic quasineutral plasma in semiconductor structures. The frequency range of such oscillations can be extended to the terahertz region by scaling down the length of structures. Our analysis shows that silicon is a promising material for prospective NEM-based terahertz wave generators. We also found that comparing to Si QWRs, Si QWs are preferable structures for NEM-based generation in the terahertz range.
Energy dispersion relations, Tight-binding model, Negative effective mass, Quantum well, Quantum wire
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