Injection transistor-transistor logic (i.t.t.l.)

A new circuit is described that comprises a lateral-multiemitter vertical transistor structure and an inverter transistor. The circuit acts as an injection transistor-transistor logic (i.t.t.l.).     

High-resolution analysis of exponentially decaying transients for physics d.l.t.s. experiments

A class of analysing functions is proposed to improve the resolution of the measurement of exponential transients in d.l.t.s. experiments. These functions offer a trade-off between resolution and sensitivity to noise as measured by a signal/noise ratio. Implementation may be by either analogue or digital (point sampling) correlation.     

High efficiency GaAs Schottky-barrier gate f.e.t. oscillator

A high efficiency high p.p.d. GaAs f.e.t. oscillator was developed. An output power of 63 mW with an efficiency of 39.7% and a p.p.d. of 0.21 mW/?m was easily produced at 9.3 GHz using a HP FET 1101 A-HPAC 100 A. The design of this oscillator was effected using a large signal method by means of a time-domain analysis program IMAG III, which computes the transient response of a nonlinear f.e.t. network.     

Tungsten/gold gate GaAs microwave f.e.t.

Preliminary results on the performance of a W/Au gate GaAs f.e.t. having T-type gate cross-section are reported. The Au overhang on the W gate can be used to self-align the source and the drain with respect to the gate, which can be used to achieve submicrometre gate dimensions rather easily. An f.e.t. with 0.7 ?m gate length and 140 ?m gate periphery exhibited a measured maximum available gain (m.a.g.) of 14 dB at 8 GHz, Experiments on the W Schottky diodes indicate that the leakage current, instead of degrading, is actually reduced by annealing at high temperature in a H2 atmosphere for 10 min.     

GaAs heterojunction f.e.t. with epitaxial Ge gate

A Ge heterojunction-gate GaAs f.e.t. has been developed using p-type epitaxial Ge gates deposited by vacuum evaporation on heated n-type GaAs substrates. Boron-ion implantation of the gate and an aluminium overlay was used to lower the gate resistance. A typical 8 ?m gate-length device exhibited a noise figure of 5.2 dB with 4.5 dB associated gain at 1.8 GHz.     

Transient thermal response of amplifying gate thyristors

A computer-aided investigation of the transient thermal behaviour of amplifying gate thyristors (a.g.t.s.) has been performed by taking into consideration the nonlinear properties of silicon over a wide range of temperature excursions.     

An improvement for the t.l.m. method

A simple improvement of the t.l.m. method is proposed. The choice of a Hanning window instead of the rectangular one which is usually preferred allows a drastic reduction of the number of iterations required to obtain a fair response.     

Synthesis and analysis of d.l.t.s. spectra from m.o.s. surface states

Given Nss and ?ss as functions of energy and temperature, a procedure is developed to synthesise d.l.t.s spectra under arbitrary experimental conditions. Methods of analysis are then considered to determine Nss and ?ss from capture experiments.     

Numerical solution of lossy waveguides: t.l.m. computer program

The transmission-line-matrix method is a time-domain numerical method for solving wave problems. The method uses a mesh of transmission lines to represent a propagation space, and the losses in the space are accounted for by making the transmission lines lossy. Lossy boundaries are simulated by imperfect boundary reflections on the transmission lines. A FORTRAN program implementing this technique is presented.     

Effects of laser irradiation of GaAs observed by d.l.t.s.

A Q-switched ruby laser has been used to heat-treat vapourphase-epitaxial (v.p.e.) GaAs. The characteristic A-centre, a deep trapping level at 0.83 eV, is removed using a laser pulse of energy density 0.3 J cm?2. Trapping levels are observed using deep-level transient spectroscopy (d.l.t.s.).     

Load-line analysis of i.i.l.

A d.c. load-line analysis of i.i.l. structures is performed. Calculations are made of logic levels, noise margins and effective circuit parameters. Although the analysis is simple, it enhances the understanding of the circuit operation, and its predictions are in agreement with experiment and with more complicated analyses.     

Effect of operating conditions on reverse gate current of junction f.e.t.s

With some types of nchannel junction f.e.t.s the measurement of gate leakage current under operating conditions (with a current flowing in the channel) has shown a very much higher value than would be expected from the maker's specification of IGSS. The excess gate current which flows at higher channel voltage is proportional to the drain current and has a small negative temperature coefficient.     

Electrically-variable optical-beam deflection and focusing with p.l.z.t. ceramics

Discs of the ferroelectric ceramic p.l.z.t. have been used for electrically controlled light-beam deflection, with deflection angles up to 6°. and for mirrors of electrically variable focal length. The two techniques, both with nonvolatile memory, should find applications in optical instruments.     

Analysis of a wide range of microwave resonators: t.l.m. methods

The solution of large m.i.c.-subassemblies presents a major problem to any numerical method. However, it would seem that the first step should involve a numerical routine of a very general nature for simple discontinuities in 3-dimensional structures. The letter describes how the t.l.m. method of numerical analysis in the form of a very general computer program fulfils this requirement.     

Gigahertz p-channel enhancement silicon m.o.s.f.e.t. with nonoverlapping gate

The technological and electrical parameters of p-channel enhancement silicon m.o.s.f.e.t.s with recessed gates are presented and compared with conventional structures fabricated in a similar manner. In the instance of the nonoverlapping gate the gain-bandwidth product is increased by a factor of about 3. The maximum frequency, as obtained by extrapolation of measurements up to 1 GHz, is f/SUB max//spl ap/3 GHz. If the depletion region of the drain contact is too short to overlap with the gate field, the static characteristics follow a space-charge-limited current-voltage relation. When higher source-drain voltages are applied the normal enhancement-type behavior results but with reverse transconductance y/SUB r/ strongly reduced (by a factor of 8-12 at 1 GHz). A higher circuit stability is obtainable, whereas the parameters y/SUB i/,y/SUB 0/, and y/SUB f/ are only slightly influenced.     

Laser annealing of low dose Se-implanted GaAs studied by d.l.t.s.

Deep level transient spectroscopy (d.l.t.s.) has been applied to the study of deep levels in GaAs following post-implantation annealing using a Q-switched ruby laser. High concentrations (> 1015 cm?3) of deep trapping levels are observed in the laser melt region using a forward-bias voltage pulse.