Silicon-on-sapphire m.o.s.f.e.t.s fabricated by back-surface laser-anneal technology

Self-aligned aluminium-gate silicon-on sapphire (s.o.s.) m.o.s.f.e.t.s have been fabricated by applying laser-anneal technology from the back surface for activation of the ion-implanted channel layer. The threshold voltage and surface electron mobility were similar to the conventional silicon-gate m.o.s.f.e.t.s, but the low resistivity of gate and interconnection electrodes using aluminium is advantageous for high switching speed m.o.s. l.s.i.     

Silicon-on-insulator m.o.s.f.e.t.s fabricated on laser-annealed polysilicon on SiO2

N-channel-enhancement and light-depletion-mode m.o.s.f.e.t.s have been fabricated on laser-annealed 0.5 ?m polysilicon films, deposited on 1 ?m of SiO2 grown on single-crystal silicon substrates. Threshold voltages of 0.35?0.45 V and ?0.5 ? ?0.7 V and surface mobilities of 170 cm2/Vs and 215 cm2/Vs were obtained on the enhancement and depletion devices, respectively. These results compare favourably with values realised in silicon-on-sapphire (s.o.s.) and bulk N-m.o.s. devices. In addition, the measured source-drain leakage currents match the best reported values for s.o.s. devices.     

Conversion gain of m.e.s.f.e.t. drain mixers

A theoretical analysis of the gain properties of m.e.s.f.e.t. drain mixers is presented. The m.e.s.f.e.t. model includes the nonlinearity of both the transconductance and the drain resistance. For a special case, a simple analytical expression for the gain is given. Numerical results for a typical example are briefly presented as an illustration.     

Offset-voltage temperature-coefficient in dual m.o.s.f.e.t. source followers

A technique is given for predicting the approximate temperature coefficient of offset voltage of a differential m.o.s.f.e.t. source-follower arrangement incorporated in a unity-gain buffer amplifier set up for zero offset at room temperature. The prediction is dependent on only one measurement, using a bridge-circuit technique, and takes account of possible power-law differences in the nominally matched dual m.o.s.f.e.t.s.     

New n-channel m.o.s.f.e.t.s

By using plasma c.v.d. and lift-off, an n-channel m.o.s.f.e.t. with effective channel length of 0.4 ?m has been fabricated. Its main fabrication processes and obtained electrical characteristics are described.     

Depletion-type m.o.s.f.e.t.s for low-temperature operation

Taking carrier freeze-out into account|a novel structure for depletion-type m.o.s.f.e.t.s suitable for low-temperature operation is proposed. Its channel consists of two regions; a relatively wide, low-impurity-density region and a relatively narrow, high-impurity-density region. It is estimated that the proposed structure has more square-law-like load character istics and higher current density than conventional ones.     

Implanted Si m.o.s.f.e.t.s for high-speed applications

Si m.o.s.f.e.t.s with a channel length of 0.8 ?m have been fabricated using boron implantation to adjust the threshold voltage. With microwave design appropriate to keeping the parasitics small, fmax values between 10 and 12 GHz are realised also with ion implantation. Large-signal switching times of 48 ps, small-signal switching times of 44 ps and delay times of 50 ps have been achieved.     

Leak-compensated analog memory with pair m.o.s.f.e.t.s

A fast, simple, and relatively stable analog memory element is proposed, composed of two condensers and a pair of complementary m.o.s.f.e.t.s. The memory element was made sufficiently stable by the use of complementary m.o.s.f.e.t.s to enable a learning machine to complete the learning process within a comparatively short time.     

n- and p-channel m.o.s.f.e.t.s as Rayleigh-surface-wave detectors

We have studied the piezoresistance effect in an m.o.s.f.e.t. structure used as a Rayleigh-surface-wave transducer. The investigation was carried out over a large frequency range about a central value of 100 MHz. Results for silicon?m.o.s.f.e.t. n- and p- channel inversion layers are given.     

Low-noise microwave f.e.t.s fabricated by molecular-beam epitaxy

The growth of m.b.e. GaAs suitable for f.e.t. fabrication is reported. The m.b.e. structure consists of an n+ = 2.5×1018 cm?3 contact layer on top of an n+ = 3.5×1017 cm?3 active layer. Using this material, f.e.t.s. have been fabricated that have a minimum noise figure of 1.5 dB with an associated gain of 15 dB at 8 GHz. These are the best results yet reported for low-noise m.b.e. GaAs f.e.t.s.     

Power m.o.s.f.e.t. linear h.f. amplifiers

N-channel silicon m.o.s. transistors for h.f. power applications have been fabricated which are optimised for linear amplification. These devices exhibit 2 W output power and 11 dB power gain at 630 MHz in class-A operation. The intercept point for third-order intermodulation distortion is 48dBm, which is considerably more than the same data obtainable with bipolar transistors.     

InP/Al2O3n-channel inversion-mode m.i.s.f.e.t.s using sulphur-diffused source and drain

InP metal-insulator-semiconductor field-effect transistors (m.i.s.f.e.t.s) have been fabricated using c.v.d. Al2O3 as the gate insulator and the sulphur-diffusion process for source and drain. The n-channel inversion-mode device exhibits normally off behaviour. A maximum d.c. transconductance gm of 10 mS (87 mS/mm of gate width) has been obtained.     

Test of the thermal-noise hypothesis in m.o.s.f.e.t.s

Evidence is given that, for m.o.s.f.e.t.s, another source o noise besides thermal noise must be operating in the conducting channel.     

GaAs m.a.o.s.f.e.t. memory transistor

A new non-volatile memory device is reported. This device is a GaAs m.o.s.f.e.t. with charge storage in the gate in which is a double oxide structure of aluminium oxide and GaAs native oxide, both oxides are grown anodically. The fabrication of the device is described and the results of initial measurements on the charging and charge retention properties are presented.     

Etched Schottky-barrier m.o.s.f.e.t.s using a single mask

A simplified method for fabricating silicon m.o.s. transistors using a single photographic mask is described. The source and drain regions are etched; underetching the oxide results in autoregistration of the gate. The characteristics of both Schottky-barrier and p?n junction source and drain devices are presented.     

Four-quadrant multiplier using m.o.s.f.e.t. differential amplifiers

This letter describes an arrangement of two current-biased and one voltage-biased m.o.s.f.e.t. differential amplifiers. The circuit is suitable for a 4-quadrant multiplier of quite good linearity in a wide output-current range.     

New structure of enhancement-mode GaAs microwave m.o.s.f.e.t.

This letter proposes a new feasible device structure of an enhancement-mode GaAs deep-depletion m.o.s.f.e.t. as an attractive alternative to the junction-gate f.e.t.s and describes its microwave properties. The device has been fabricated on a high-resistance epitaxial n?-layer by simple readily available technology without requiring the sophisticated control of the channel thickness needed for the conventional junction-gate f.e.t.s. The 'normally-off nature of the device can be explained on the basis of the substrate space-charge region extending over then?-layer. The microwave performance of the device can be favourably compared with that of currently achievable junction-gate normally-off f.e.t.s. Unilateral gain drops to zero at a frequency slightly above 7 GHz.     

Low-noise GaAs m.e.s.f.e.t.s

GaAs m.e.s.f.e.t.s with optimum noise figures of 1.6 dB at 6 GHz have been fabricated by projection photolithography. An equation has been developed for the calculation of optimum noise figure which gives good agreement between calculated and measured values.     

Electron dynamics in P-Si m.o.s.f.e.t. inversion channels

An attempt is presented in modelling at room temperature the carrier dynamics in the inversion layer using a Monte Carlo simulation. The interaction of inversion carriers with the surface is regarded successively as perfectly specular and perfectly diffuse. A comparison of the results with the experimental data of Coen and Muller gives reasonable agreement in a wide range of electric field.     

Analysis of field distributions in a GaAs m.e.s.f.e.t. at large drain voltages

Electric-field distributions and carrier-density distributions in a GaAs m.e.s.f.e.t. at large drain voltages are investigated with a new analytical model, which takes account of the electron-drift-velocity saturation with negative differential mobility and the extension of a depletion layer towards the drain electrode.