Generation-recombination noise in the channel of GaAs Schottky-gate field-effect transistors

The low-frequency noise in GaAs m.e.s. f.e.t.s was measured continuously for temperatures varying from 80 to 310K. It presented distinct maxima, suggesting the presence of several g.r. processes. The shift of these peaks at different frequencies (500 Hz to 1 MHz) allowed us to obtain the time constants and the activation energies of four trapping levels. The noise reported here could stem from multilevel trapping in the channel.     

Model of the diode-connected GaAs Schottky-gate field-effect transistor

A model of the diode-connected GaAs Schottky-gate field-effect transistor (SFET) has been proposed. The SFETs with uniform and δ-doped channels are considered. The model accounts for the distributive character of the channel’s resistive regions under the gate and the passive contact regions between the gate and the ohmic contact. Based on the results obtained, the equivalent circuit of the diode-connected SFET, which accounts for the current displacement effect, and the method to measure its parameters have been suggested. The model may be used for heterostructure FETs with high electron mobility in the channel (HEMT).     

Output-resistance properties of the GaAs Schottky-gate field-effect transistor in saturation

Some new experimentally observed properties of the output resistance of GaAs Schottky-gate f.e.t.s in saturation are described. A phenomenological model is proposed in which the structure is divided into two sections: a source section, where the approximation is assumed to be gradual, and a drain section, where the drain current is included in the `equivalent doping?. At high drain currents, the experimental results are found to correspond well with the theory.     

The DC, AC, and noise properties of the GaAs/AlGaAs modulation-doped field-effect transistor channel

The channel noise of a normally-on MODFET has been measured atT = 300K as a function of bias and frequency. The results are in good agreement with theoretical predictions for velocity fluctuation noise. A new method is introduced to calculate the correct dependence of the two-dimensional carrier concentration on channel voltage. The measurements indicate that real-space-charge transfer in the bias range considered is negligible.     

Modeling of ionizing irradiation influence on Schottky-gate field-effect transistor

Mechanism of radiation effects in semiconductor (GaAs) is described. Analytic and numerical (equivalent circuit and quasi-hydrodynamic methods) models of ionizing irradiation influence on semiconductor devices are discussed. The GaAs microwave MESFET was selected as the investigation object. The combination of the quasi-hydrodynamic and equivalent circuits methods should provide a possibility to take into account all essential effects and at the same time to save the computation time in comparison with Monte Carlo method.     

Trapezoidal-groove Schottky-gate vertical-channel GaAs FET (GaAs static induction transistor)

This letter reports, the development of a vertical-channel. GaAs FET with the unsaturatedI-Vcharacteristics of the static induction transistor (SIT) and voltage blocking capability up to 100 V. The device structure utilizes the anisotropic etching properties of GaAs, in which the gate regions are formed by a double-angle evaporation into trapezoidal etched grooves. This single evaporation step simultaneously provides both source and gate metallization, and the novel trapezoidal groove geometry automatically yields a self-aligned gate with separation of source and gate onto different levels, thus eliminating the need for critical alignment arising from source-gate interdigitation.     

Planar monolithic integration of a GaAs photoconductor and a GaAs field-effect transistor

A planar monolithic integrated photoreceiver suitable for 0.8 ?m-wavelength optical communication systems has been realised. It consists of a GaAs photoconductor associated with a GaAs FET. The steady state and dynamic gains and the noise properties of the photoconductor and of the integrated circuit have been investigated.     

High-frequency noise of the junction field-effect transistor

Based on Geurst's treatment of the high-frequency value of the admittances of the junction field-effect transistor, the high-frequency noise of the device has been computed, assuming that the noise source is of thermal origin. By applying an appropriate series expansion of the current it is possible to express the noise of the drain and gate current in terms of known quantities, as steady-state transconductance, gate capacitance, and frequency. At low frequencies the noise spectrum of the drain current is independent of the frequency and is much larger than the noise of the gate current; however, at high frequencies the noise spectra of the gate and drain current both vary by ω²and are of the same order of magnitude.     

Monolithic integration of GaAs photoconductors with a field-effect transistor

A one-stage monolithic integration of a tandem pair of GaAs photoconductors (PCs) with a field-effect transistor (FET) is reported. The PC-FET exhibits a bandwidth in excess of 1 GHz and a gain of 6 dB at midband. A very low noise figure of ~3 dB in the FET is also achieved.     

Experimental study of surface channel in insulated-gate field-effect transistor

A simple experimental technique is described for measuring the effective channel length and the surface-channel drift mobility in the insulated-gate field-effect transistor. Experimental results are presented for p channel transistors made in 8 ? cm silicon.     

Band-bending effect of low temperature GaAs on a pseudomorphic modulation-doped field-effect transistor

Low temperature photoluminescence (PL) measurements on pseudomorphic modulation-doped transistors with a low-temperature (LT) GaAs layer in the GaAs buffer layer clearly show a decrease in the quantum well PL transition energies compared to a structure with no LT GaAs. Self-consistent calculations of the electron and hole bandstructure suggest that the observed increase in the redshift in PL energies with increasing quantum well-LT GaAs spacing can be attributed to band bending induced by the Fermi level pinning at the undoped GaAs/LT GaAs interface and a novel carrier compensation effect of LT GaAs.     

An InAs channel heterojunction field-effect transistor with hightransconductance

A report is presented on an InAs channel field-effect transistor (FET) based on AlGaSb/InAs/AlSb/AlGaSb structures grown by molecular-beam epitaxy. Excellent pinch-off characteristics have been obtained. An FET with a gate length of 1.7 μm showed transconductances ranging from 460 mS/mm (at V_ds=0.5 V) to 509 mS/mm (at V_ds=1 V) and a K factor of 1450 mS/Vmm (at V_ds=1 V) at room temperature     

Anomalous noise behavior of the junction-gate field-effect transistor at low temperatures

Measurements are reported on the noise resistance and the noise conductance of the junction-gate FET in the temperature range 77°K-400°K. At low temperatures anomalous noise behavior has been observed. The measurements are discussed in the light of existing theories and, when necessary, the theoretical model has been extended. The agreement is satisfactory. Generally the extra noise is caused by mobility saturation, increased free-carrier temperature, free-carrier trapping and multiplication effects in the pinched-off region. Finally, several applications are discussed in relation to the limiting noise sources.     

Low-frequency noise in GaAs Schottky-gate f.e.t.s.

Measurements of the low-frequency noise in GaAs Schotty-gate f.e.t. channels have been performed from 10 Hz to 0.5 MHz between ?120 and +21 °C. Diffusion and recombination noise sources appear to be predominant at low temperatures for low-power-level conditions. Nous avons entrepris la mesure du bruit basse fréquence prenant naissance dans le canal des f.e.t. à l'arséniure de gallium pour des fréquences allant de 10 Hz à 0. 5 MHz et une température comprise entre ?120 et +21 °C. Nous avons mis en évidence que pour de faibles puissances dissipées les sources de bruit principales à basse température ont pour origine des phénomènes de diffusion et de génération recombinaison.     

A high voltage-gain GaAs vertical field-effect transistor with anInGaAs/GaAs planar-doped barrier launcher

A high voltage-gain GaAs vertical field-effect transistor (VFET) with an InGaAs-GaAs pseudomorphic planar-doped barrier (PDB) launcher is described. The pseudomorphic structure, which includes a small amount of indium in the launcher, was grown by molecular beam epitaxy (MBE). Fabricated transistors, with good pinch-off characteristics (gate threshold voltage of -1.6 V), have exhibited DC open-drain voltage gains of up to 50 at 77 K. This high voltage gain results from the combination of high transconductances and low output conductances. The former are attributed to velocity enhancement by hot-electron injection, and the latter are attributed to the suppression of electron spillover by energy band discontinuity at the heterointerface between the launcher and the channel     

n+ -GaAs/undoped GaAlAs/undoped GaAs field-effect transistor

The first self aligned accumulation-mode GaAs MIS-like FET having an n+ -GaAs/undoped GaAlAs/undoped GaAs structure is reported. The FETs fabricated show the threshold voltage of almost zero (V?th = 0.035 V) and very uniform (?Vth = 0.013 V) characteristics, as expected. The transconductance is as high as 170 mS/mm, which is the highest value ever reported on GaAs MIS-like FETs.     

D’yakonov-Shur instability in a ballistic field-effect transistor with a spatially nonuniform channel

The instability of a two-dimensional electronic liquid in the channel of a ballistic field-effect transistor is analyzed by investigating the energy balance. A criterion of instability is found for arbitrary boundary conditions. Using energy-balance analysis we propose a device with a high instability growth rate. The transistor possesses a spatially nonuniform channel and is analogous to a divergent channel in classical hydrodynamics. Our computed growth rate and threshold of the instability for this device agree with the computational data. Fiz. Tekh. Poluprovodn. 33, 619–628 (May 1999)     

Theory of generation-recombination noise in the channel of junction field-effect transistors

A new derivation is given for the noise in JFET's stemming from generation-recombination or trapping processes in the channel. For the case of a delta function carrier covariance, the result is the same as that of van der Ziel. However, the present derivation is more direct and can be easily extended to more general cases.     

Effects of intervalley scattering on noise in GaAs and InP field-effect transistors

The results of a dynamic analysis of electron transport in GaAs and InP have been used to determine the effects of device cooling, channel length, and frequency of operation on the noise performance of FET's made of these materials. Noise temperature of the material as a function of electric field is first obtained by an analysis that models intervalley scattering using a Monte Carlo calculation method. Noise figure of the intrinsic device is then obtained using a gradual-channel analysis. The validity of such an analysis is discussed. Both GaAs and InP FET's should exhibit very good low-noise performance, with the intrinsic InP device somewhat noisier than the GaAs device at equivalent values of f/fT. For GaAs the intrinsic noise figure can be considerably reduced as the device is cooled, but for InP, cooling from 300 to 77 K should leave intrinsic noise figure almost unchanged.     

On the field-effect transistor characteristics

A theoretical analysis demonstrates that the relationship between IDand VDSfor one value of VGSis sufficient to completely describe the device behavior for any channel impurity profile. A simple graphical procedure is given to generate a complete set of characteristics from the results at one value of VGS. Measurements on ann-channel FET are given to support the theoretical conclusion and to demonstrate the graphical technique.