摘要:

The current state of gigabit logic is presented. Recent developments have made a significant contribution to this field, and it is the purpose of this' work to compare these new developments with the more traditional approaches. The relationships between device and circuit parameters are derived in an Appendix, and these relationships are used to explore the conditions which must be satisfied by the devices if they are to offer gigabit logic operation. To meet large system requirements, it is shown that the highest levels of integration must be used: for a given complexity the requirements of individual components, e.g. power dissipation, parameter tolerances, are derived. The various circuit types, including the recent results from HEMTs and submicron silicon MOSFETs, are discussed. For the purposes of this review, only those devices which have already been integrated are studied; thus bipolar III-Vs, permeable base transistors and other similar devices are not discussed. The developments in submicron silicon present a challenge to GaAs speed superiority. This potential superiority forms the basis of the discussion in the paper, together with a projection for the future.

DOI:10.1049/ip-i-1.1982.0036

出版商:IEE    

年代:1982

数据来源: IET

摘要:

High-voltage power device performance is often limited by the ability to approach nearly ideal behaviour at the edges of the chip. Consequently, a large number of termination techniques have been explored to reduce the surface electric field at the edges of devices, and so to maximise the breakdown voltage. The paper provides a review of these techniques. A comparison between the various approaches is then performed with consideration for device type (thyristors, field-effect transistors, transistors etc.) and device die size. This comparison is intended to serve as a guide to choosing the device termination appropriate for each application.

DOI:10.1049/ip-i-1.1982.0037

出版商:IEE    

年代:1982

数据来源: IET

摘要:

Both ruby laser and CW argon ion laser irradiation increase the electrical conductance of doped hydrogenated amorphous-silicon films. The ruby laser produces the larger effect, not only due to activation of phosphorus dopant in the film, but also as the films are crystallised. These permanent conductivity changes are distinct from the reversible changes observed in lightly doped or undoped films. These latter changes have dramatic effects on the current/voltage behaviour of Ni or Al Schottky diodes owing to changes in the density of gap states, and may be reversed by thermal annealing to 150°C. Because of the increased dielectric relaxation time of laser-irradiated films, the capacitance/frequency curves no longer give a clear indication of space-charge width. Al diodes have an additional irreversible change produced by laser diffusion of Al or oxygen, and are greatly improved rectifying devices after laser irradiation and thermal annealing.

DOI:10.1049/ip-i-1.1982.0039

出版商:IEE    

年代:1982

数据来源: IET

摘要:

A very simple and straightforward relationship has been derived between the direct transconductance and the apparent electron saturation drift velocity in GaAs MESFETs. From a comparison with experimental data it was found that this velocity may exceed the usual equilibrium velocity value. A new semiempirical relationship between the apparent non equilibrium velocity and the gate length is suggested. This relationship provides good agreement with both published experimental data and published Monte-Carlo numerical simulations. The practical implications on the saturated current at a given gate voltage, and on the maximum available transconductance per unit gate width for a given gate length and a given epilayer thickness are outlined. Moreover, the validity of present results for ion-implanted MESFETs is tested.

DOI:10.1049/ip-i-1.1982.0041

出版商:IEE    

年代:1982

数据来源: IET

摘要:

The MBE growth on InSb (and CdTe) of thin films of tin with diamond structure led to two unexpected findings: (i) photovoltaic behaviour suggesting an energy gap of 0.12eV, (ii) stabilisation of the diamond structure to about 70°C (compared with 13°C for bulk material). One explanation of semiconductivity is a strain-induced splitting of the Groves-Paul degeneracy which has been taken to confer semimetallic behaviour. Alternatively, if less probably, MBE material is free from Hg contamination (present in almost all earlier material), and Hg could act as both donor (interstitial) and acceptor (substitutional), which could compensate to give quasi-gap-bridging impurity bands in an intrinsically semiconducting material. Piezoresistance or other band measurements sensitive to band symmetry on MBE α-Sn are urgently needed to clarify the situation. The substrate stabilisation effect suggests that it could also be possible to stabilise films of the previously unknown (Sn, Ge) solid solutions by using appropriate substrates, e.g. InAs for compositions near Sn0.5Ge0.5Such material could have considerable device interest: a direct gap of about 0.3 eV should be paired with higher carrier mobility (because of absence of polar scattering) than III-V or II-VI materials with a similar gap.

DOI:10.1049/ip-i-1.1982.0043

出版商:IEE    

年代:1982

数据来源: IET

摘要:

The paper presents the analysis of a switched optoelectronic microwave load which can work either as a laser-controlled, matched or adjustable, resistive load or as a high-speed optoelectronic microwave switch. The device consists of a GaAs microstrip section controlled by a pulse-operated laser diode via substrate-edge-excitation. The exponential decay of photoconductivity across a longitudinal section of the microstrip forms a laser-induced electron-hole plasma wedge that works as a lossy tapered transmission-line section. The specific microwave power distribution within the excited region is derived in detail, as is the total input reflection coefficient under two special operating conditions (open-ended section and matched section). Numerical results are presented for a 906 nm excitation.

DOI:10.1049/ip-i-1.1982.0044

出版商:IEE    

年代:1982

数据来源: IET