Simulation of GaAs/AlGaAs RTD using One-Band Combined Model

Presented in this paper are investigations regarding garding the influence of doping concentration in RTD barriers and on IV-characteristics. One-band combined RTD model [1,2] is based on semiclassical and quantum-mechanical (the wave-function formalism) approaches. It takes into account the effect of charge in different regions, including surface charge at heterointerfaces, the shape of band offsets, scattering in the quantum well, and resistances of extended passive regions. In order to describe the barrier and quantum well shapes, hyperbolic approximation [3,4] has been used. The potential profile in this case is approximated by the function (1). IV-characteristics calculation was carried out for double-barrier RTD made of GaAs/AI0,4Ga0,6As. Its structure and parameters are presented in fig.1. Presented in Fig.2 are IV-characteristics of RTD using one-band combined model for three different doping concentrations: 2·1023 m?3 (curve 1), 2·1022 m?3 (curve 2) and 2·1021 m?3 (curve 3). Presented in Fig.3 are the results regarding the influence of barriers and well shapes approximation on IV-characteristics, in particular, coefficient ?. Curve 1 is experimental data [6]. Curves 2, 3, 4 are for ?: 0; 0.25 and 0.3. The investigations carried out demonstrate satisfactory agreement of the calculated peak current and voltage with experimental data, taking into account barrier shape coefficient ?. Good results have been obtained for different doping concentrations in regions 2 and 8. Nd decreasing causes peak voltage increasing. It is in good agreement with experimental data [6].