InP?SiO2 m.i.s. structure with reduced interface state density near conduction band

HCl addition to the SiO2 c.v.d. process was found to be an efficient method for producing n?InP m.i.s. structures with low density of interface states near conduction band. Remaining deep interface donor states approximately 0.5 eV below conduction band restrict the steady-state bias range in h.f. applications.     

Performance of p-i-n photodiode compared with avalance photodiode in the longer-wavelength region of 1 to 2 ?m

The signal/noise ratio is estimated in comparing p?i?n and a.p.d. photodetectors. In the longer-wavelength region, the p?i?n diode is expected to be superior to the a.p.d., although, in the shorter-wavelength region, under 1.0?m, the converse is true.     

New v-groove integrated injection logic

A new V-groove integrated injection logic (v.i.i.l.) is proposed which combines the V-groove technology and the double-diffused bipolar technology. The fabrication processes arc qualitatively described. The lateral p?n?p transistor of the i.i.l. is located on the vertical V-shape surface, and the effective base width is controlled by the combination of the vertical diffusion process and the V-groove etching rate. A 1-dimensional analysis is used and an approximate expression for the collector current of the lateral p?n?p transistor is given. The v.i.i.l. is expected to have a higher production yield than that of the ordinary i.i.l.     

High-efficiency oscillations in gallium-arsenide avalanche diodes

Some preliminary results are reported for an analytic theory of high-efficiency microwave oscillations in gallium-arsenide avalanche diodes. Design and performance criteria are deduced for p+?n?n+ and n+?p?p+ structures, and a comparison is made with experimental work.     

High-efficiency p?n junction GaAs IMPATT devices

GaAs IMPATT devices using p+?n and p?n junctions with hi?lo and lo?hi?lo structures were investigated. A maximum efficiency of 26.8% and a maximum peak power of 12.8 W with 25% efficiency have been observed in the X band. A median life of 107 h is predicted for a 237°C junction temperature.     

Solution of the Lyapunov matrix equation with a diagonal input matrix, obtained without matrix inversion

The solution of the Lyapunov matrix equation A?L+LA=?K with K=diag (?i), i=1, 2,?, n, is obtained via the Schwarz canonical form, by a method which requires no matrix inversion. The matrixes involved are formed by simple recursive schemes. A restriction on validity is that, corresponding to each nonzero ?i and the ndimensional row vector y?, the only nonzero element of which is unity in the ith position, the n×n matrix Ni, the rows of which, taken in sequence, are y?, y?A, ?, y?An?1, must be nonsingular. At the cost of a matrix inversion, the scheme may be extended to the case that K is any symmetric real matrix.     

GaAs n+-p?-n+ ballistic structure

Potential distribution and I/V characteristics of short n+-p?-n+ devices are calculated assuming ballistic electron transport (no collisions). The results of the calculation are in good agreement with experimental results for submicrometre GaAs n+-p?-n+ structures.     

Determination of an initial mesh for computer simulation of semiconductor devices with nearly abrupt junctions

A computer procedure to determine the initial potential distribution in the vicinity of semiconductor junction structures is outlined. It is useful for either n+?n or p?n structures and has the advantage that the mesh spacing is generated in such a way that its use for modelling under nonequilibrium conditions satisfies the stability requirements outlined by Seidman and Choo.     

Synthesis and Number of all Series-Parallel Structures with n Components

A synthesis procedure and?as a by-product?the number of different redundant structures for series-parallel systems with n components is derived. The reliability graphs of these structures, especially their fault trees, are branched like true rooted trees in the sense of graph theory. The results might be useful for some reliability optimization procedures and other applications.     

Optimal Selection Methods for Failure & Repair Rates Using Nomographs

This paper explains the optimal selection methods using nomographs to solve two essentially different problems. The one is the problem of unit level, and the other is the one of system level. The unit level assumes that the cost information as a function of failure rate ? and repair rate ? are empirically known. The paper presents a method, by which a nomograph is used to select easily the optimum pair from the infinitely many pairs (?, ?) of feasible solutions, to gain the required unit availability at minimum cost of this assumption. At the system level, the system is composed of n serial i-units which are selectable from a group provided for each i-unit (i = 1, 2, ..., n), several different repair plans are available for the unit. Each unit has a specific failure rate and associated cost, and each repair plan has a specific repair rate and associated cost. There are service personnel for each unit. The failure and repair rates are constant. The paper presents: 1) A method using nomographs to select the optimum pairs from the many pairs (?i, ?i) (i = 1, 2, ..., n) of feasible solutions, to gain the required system availability at the minimum system cost, 2) A method to select the optimum pairs, from the many pairs (?i, ?i (i = 1, 2, .     

Temperature rise of pin diodes from X band pulses

When pin microwave silicon switching diodes are subjected to high-power Xband pulses, the absorbed energy is not distributed uniformly. An apparent peak temperature delay is evidenced when using the junction forward-voltage characteristics as an indicator, and is explained by assuming a model with heat generation in the centre of the i region and the n?i and p?i junctions as sensors.     

Emission of HF radiation in n+n(x)n+ GaAs devices under crossed electric and magnetic fields

Physical arguments are presented to investigate the possibility of altering Landau levels by varying the doping density in the active n-layer in sandwiched n+n(x)n+ structures. Energy eigenvalues obtained from the solution of the Schr?dinger equation provide the frequency range of possible radiation emission.     

Single-pole double-throw p?i?n diode switch for the band 150?1000 Mc/s

The construction of a single-pole double-throw diode switch is described. Measurements show the reduction of intermodulation products resulting from the use of p?i?n diodes rather than resistive or varactor diodes.     

Photoelastic optical directional couplers in epitaxial GaAs layers

Photoelastic channel optical waveguides showing strong lateral confinement at ?=1.55 ?m have been fabricated by etching a narrow slot through a Au Schottky contact deposited on an n/n+ GaAs layer. Such structures allow electro-optic directional coupler switches of short coupling length (~2 mm) to be easily realised.     

投影电视光学系统和部件

光学系统和光学部件是投影电视核心技术的重要组成部分。光学系统包括光学图像的形成和光学图像的投射两部分。本文介绍投影电视的分类，光学系统设计目标和光学部件。提出并分析光学系统的分类表，得出若干重要结论。     

Source-drive optimisation for optical-fibre systems using l.e.d.s

The influence of the source-drive duty factor on the performance of a digital fibre-optic communication system is explored. The system considered utilises an l.e.d. source and either a p?i?n or avalanche photodetector. It is shown that, for a fibre with known dispersion, an optimum duty factor exists which offers significant s.n.r. advantages over a system with impulsive excitation.     

X-band circular waveguide switch with polarisation diversity

A p?i?n diode X-band circular waveguide SPST switch with polarisation diversity has been designed, fabricated and tested. Special design of the bias circuits ensures minimum insertion loss, better than 0.1 dB, and maximum isolation of 29 dB at X-band frequencies.     

Q factor, Q stability and gain in active filters

This letter sets out a simple theory relating the maximum Q factor of a second-order active-filter section to the stability of that Q factor and the available gain in the active elements used. The theory is shown to apply to both the `negative-feedback? or `Rauch?-type filters and `positive-feedback? or `Sallen?Key?-type filters and by implication to negative-impedance convertors (n.i.c.s) and the whole family of circuits based on minimum-phase feedback networks.     

Optical wavelength response of Ta/p-Si position-sensitive detectors

Position-sensitive detectors, PSDs, are precision optical sensors that operate using the lateral photovoltaic effect. Most commercial and, to a large extent, research devices are based on p–i–n structures involving high-temperature diffused junctions. Our programme is aimed at producing devices that perform as well as commercial devices with desirable response characteristics and extended longevity but based on a more straightforward fabrication technique. In this work we investigate the response of one-dimensional Schottky barrier PSDs fabricated using tantalum films deposited on silicon by electron-beam evaporation, a technique which produces very pure and uniform films and permits repeatable devices to be fabricated. Tantalum was selected for its appropriate electronic properties and the potential for forming long-lived, robust and stable detectors. Here we compare the response of these devices at various thicknesses under different light sources. An optimal thickness of tantalum, trading off transmissivity against good Schottky barrier formation, has been determined as approximately 200?Å. These devices were tested under various light sources: white light, filtered light and a red diode laser. The best properties were found under a 5?mW red broadband filtered light, producing better than 7?mV/mm and excellent linearity.     

InP-Langmuir-film m.i.s. structures

The electrical properties of m.i.s. structures based on InP and Langmuir films have been investigated. A strongly inverted low-frequency-type C/V response occurs at about 30 Hz. Surface-state distributions have been evaluated by using both quasistatic and conductance techniques. Effective surface-state densities are found to be ~3 × 1011cm?2 eV?1 over a large fraction of the band gap.