摘要:

The physical properties of the important lll-V semiconductor materials and devices are reviewed. Electrical and optical devices are included and comparisons are made between materials, including silicon, to explain the choice for a particular application.

DOI:10.1049/jiere.1987.0012

出版商:IERE    

年代:1987

数据来源: IET

摘要:

A new type of heterojunction bipolar transistor, designated the BICFET, (for Bipolar Inversion Channel Field Effect Transistor), is proposed. Unlike the conventional heterojunction bipolar transistor (HBT), the BICFET does not have a base. Instead, it relies on a field effect action to induce and modulate an inversion channel (which replaces the base) at the interface between the wide- and narrow- bandgap materials, to control current flow in the system.The BICFET has the high current gain associated with HBTs. However, since the BICFET does not have a base layer, it does not experience the deleterious base layer effects, such as charge storage, recombination, base transit time, etc. In particular, it has a much lower input capacitance and the capability of much higher current drive than a HBT, the combination of which augurs well for very high speed operation.In addition to the basic theory, common-emitter (CE) output and input characteristics are generated for two practical systems, and a possible integrated structure is indicated. A small-signal CE model for the device is also presented. The model predicts h cut-off frequencies as high as 10,000 GHz; however, in practice, collector transit time effects will reduce the cut-off frequency to about 600 GHz.

DOI:10.1049/jiere.1987.0013

出版商:IERE    

年代:1987

数据来源: IET

摘要:

For many years the GaAs MESFET has provided enhanced performance in a wide range of u. h. f. and microwave systems. GaAs digital i.c.s., also using depletion MESFET technology, are now available in research laboratories of many systems companies and commercially. The basic gate delay of ̃ 50 ps provides s.s.i. and m.s.i. functions to exploit the high-speed communications capabilities of optical fibre systems, operating at up to 4 Gbit/s.The main features of the fabrication technology are given for comparison with modern silicon fabrication techniques. Process monitoring for control and device characterization are particularly important to achieve good yield and reproducibility and to minimize the spreads in parameters used for circuit design. High-speed circuit performance depends critically on design and layout and requires careful simulation, including the effects of parasitics and the package. The use of well-characterized ‘function cells’ is advocated to reduce the overall design effort and to improve performance predictability.

DOI:10.1049/jiere.1987.0011

出版商:IERE    

年代:1987

数据来源: IET

摘要:

The superior electrical properties of GaAs and its ability to produce heterojunctions which confine charge-carrier motion in specified directions, allows new design freedoms for bipolar transistors. This promises the realization of very fast, low power, high density integrated circuits.

DOI:10.1049/jiere.1987.0010

出版商:IERE    

年代:1987

数据来源: IET

摘要:

Sampled-analogue design technique is a rather neglected area of GaAs i. e. exploitation which has a wide range of potential applications in the area of high performance filtering through the use of the techniques described here. Although many other devices such as analogue to digital converters (ADCs) properly fall within the scope of this paper, they form a complete area of study in themselves and so are not treated in this tutorial style introduction.

DOI:10.1049/jiere.1987.0009

出版商:IERE    

年代:1987

数据来源: IET

摘要:

The design and fabrication of optical waveguides in III-V semiconductors is described. Different epitaxial growth techniques are discussed in the context of their suitability for making the types of layer structure required for optical waveguide devices. In addition, important aspects of the fabrication process, such as lithography and dry etching are described. Ill-V semiconductor waveguide devices based on different physical operating mechanisms are considered, and their relative advantages and disadvantages outlined.

DOI:10.1049/jiere.1987.0008

出版商:IERE    

年代:1987

数据来源: IET

摘要:

A review of modelling techniques used to characterize III-V semiconductor devices is presented which deals with both physical and equivalent circuit modelling techniques. The relative merits of the two approaches are examined. The application of these techniques to a wide variety of devices is discussed and a number of results presented, including a range of models for state-of-the-art devices.

DOI:10.1049/jiere.1987.0007

出版商:IERE    

年代:1987

数据来源: IET

摘要:

Field-theoretical results of high-frequency MeSFET structures are presented on the basis of a mode matching technique. Wavelengths and attenuation constants are given for frequencies from 1–100 GHz. An experimental approach with 3.2 mm transverse-length MeSFETs confirms the theoretical data. It is pointed out that such results are useful in modelling mm-wave transistors suitable for frequency ranges above 20 GHz.

DOI:10.1049/jiere.1987.0006

出版商:IERE    

年代:1987

数据来源: IET

摘要:

The theoretical model which is widely used to describe the quantum mechanical tunnelling process, namely the effective mass theory of tunnelling, is presented along with some of its limitations. The paper then describes experiments by the author and colleagues to test effective mass theory. Experimental investigations of the effect of hydrostatic pressure (up to 15 kilobar) and magnetic field (up to 11T) on the low temperature J(V) characteristics of single barrier n+GaAs/(AIGa)As/n−GaAs/n+GaAs tunnelling structures are described. The pressure dependence is accurately described by the effective mass/WKB model up to 10 kilobar. At higher pressure a rapid fall in the carrier concentration in the n+GaAs contact is observed due to pressure-induced trapping of electrons on defect levels, probably associated with the L-or X-conduction band minima of GaAs. The reduction of the tunnelling current in an applied magnetic field is discussed in terms of the effect of the diamagnetic energy in increasing the height of the potential barrier. The final section of the paper draws some general conclusionsfrom the theory and the experimental work presented.

DOI:10.1049/jiere.1987.0005

出版商:IERE    

年代:1987

数据来源: IET

摘要:

The enhancement in superlattices of α/β (electron to hole ionization coefficient ratio) in AIGaAs/GaAs and in AllnAs/GalnAs, and of β/α in InP/GalnAs, is modelled using lucky-drift theory. Agreement with observation in the case of AIGaAs/GaAs is obtained only if the old 85 :15 band-edge discontinuity rule is assumed and geometrical reduction factors are ignored. The theory of the ionization rate for nearly parabolic bands is recalled, and the crucial role of overlap integrals is discussed. Simple theory predicts that ionization processes involving light holes are much more rapid than for heavy holes. An estimate of the rate near threshold for GaAs is made and it is shown to be over a hundred times smaller than the phonon-scattering rate. The impact ionization threshold for GaAs is therefore ‘soft’, in contrast to what is normally assumed. A soft threshold has important implications for the efficient working of staircase avalanche photodiodes (APDs), and for the modelling of the impact ionization process.

DOI:10.1049/jiere.1987.0004

出版商:IERE    

年代:1987

数据来源: IET