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Solid-State and Electron Devices, IEE Proceedings I

Issue 6 • Date December 1984

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Displaying Results 1 - 6 of 6
  • Generation of electron beams for gyrotron tubes

    Page(s): 177 - 182
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (581 KB)  

    A numerical simulation of a system for generating electron beams for gyrotron tubes using solid-beam Pierce-type electron guns is described. Distributions of the electron momentum ratio ¿ = ¿¿/¿¿ are given for various parameter ranges, and the influence of space charge on the momentum spread is examined. View full abstract»

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  • Optical absorption in the window layer and its contribution to the spectral response of a pGa1-x Alx As/p-GaAs/n-GaAs solar cell

    Page(s): 183 - 187
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (425 KB)  

    The influence of the aluminium content on the photovoltaic performance of the p-Ga1¿xAlxAs/p-GaAs/n-GaAs structure is investigated. An enhanced high-photon-energy spectral response is observed when the window layer has a direct gap. Also short-circuit currents and conversion efficiencies calculated in these devices indicate high values in the neighbourhood of those obtained with a high aluminium content. This is due to the high mobilities characterising direct valley electrons; i.e. the contribution of the window layer to the cell current is greatly enhanced, to the extent that the increased photogeneration in this layer does not lead to any significant loss. View full abstract»

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  • Influence of coupled plasmon-polar optical phonon modes on the mobility of electrons in GaAs

    Page(s): 188 - 192
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    By means of time-dependent perturbation theory, the rate for the scattering of electrons from coupled plasmon-polar optical phonon modes has been derived. This rate has been expressed in a form suitable for Monte-Carlo particle modelling. The mobility of electrons in bulk GaAs has been simulated by means of this technique, both with and without the plasmon-phonon coupled modes. Although the scattering from the coupled modes is stronger than from uncoupled phonons, the energy interval over which coupled-mode scattering takes place is small. The reduction in mobility due to coupled plasmon-phonon modes is of the order of a few per cent and peaks at 1 MV m¿1. View full abstract»

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  • Monte-carlo particle model study of the influence of gate metallisation and gate geometry on the AC characteristics of GaAs MESFETs

    Page(s): 193 - 202
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (836 KB)  

    The distributions of carriers and internal electric fields have been calculated and compared for five different transistors. The doping profile underneath the 1 ¿m gate, the gate width and the positions of the source and the drain relative to the gate are the same for all devices. The stray fields from the metai gate in all transistors have been introduced to study the effect of gate trench shape and metallisation on the carriers and internal fields. We find that these stray fields improve the planar FET with respect to noise performance, while the edges of the gate trench counteract the effects of the gate metallisation. Some AC characteristics have been discussed in the view of the internal fields. For two devices, the calculations have been repeated with an n-type buffer layer inserted between the epilayer and the intrinsic substrate. This buffer was found to have much the same effect on the distributions of fields and carriers as the gate stray field had. We conclude that the gate metallisation stray field or the substrate buffer can improve the performance of the transistor, and they represent an important additional design criterion. View full abstract»

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  • MBE GaAs impatt diodes with reduced drift region for mm-wave frequencies

    Page(s): 203 - 206
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (366 KB)  

    The electron drift velocity in GaAs has been investigatd at high electric fields for dependence on temperature. MBE GaAs Impatt diodes with reduced drift region have been fabricated for 50 and 60 GHz. The results show that the lower value of electron drift velocity of 2.8 to 3.5 × 106 cm/s instead of 6.5 × 106 cm/s at 500 K should be applied in the design of GaAs Impatt diodes for mm-wave frequencies. View full abstract»

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  • Simple analytical one-dimensional model for saturation operation of the high-voltage bipolar power transistor

    Page(s): 207 - 212
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (486 KB)  

    It is shown that, by making use of a suitable generation function to represent the lateral injection of base current, it is possible to obtain a simple analytical solution for one-dimensional saturation operation of the high-voltage power transistor. The model takes account of the nonthermal equilibrium state of the majority carrier and of majority-carrier current flow, and thereby gives a realistic and useful description of low-voltage low-gain saturation operation, which is the usual on-state for such devices. View full abstract»

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