Noise GaAs Research Articles

Monte-Carlo simulation of noise in GaAs at electric fields up to the critical field

Monte Carlo noise calculations using a method based on the Ramo-Schockley theorem were carried out for n-type homogeneous GaAs under a variety of conditions. Classical Nyquist noise results were reproduced for resistors at both 77 and 300 K. The method was used to model noise at 300 K at fields up to the critical field, and the results compare favorably with those found experimentally. An alternative method for determining the intervalley coupling constant by using noise temperature data is described, and the results using this method suggest the value of the intervalley coupling constant approximately=0.5*10/sup 9/ eV-cm/sup -1/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Low-Frequency Noise in GaAs

Low-frequency noise measurements were carried out on GaAs devices in the frequency and temperature ranges from 10 Hz to 100 kHz, and from 77 K to 300 K, respectively. The noise spectra are considered to be superpositions of generation-recombination noise components caused by traps. The activation energies of these traps are determined from the temperature dependence of the noise.

Noise spectroscopy as a tool to investigate the temperature dependence of localization in a quantum Hall system.

Generation-recombination noise in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As heterostructures was investigated in the temperature range 4.2--15 K at various magnetic fields corresponding to filling factors ranging from 6 to 7. In the spectral noise intensity of the Hall voltage and in that of the longitudinal voltage, two Lorentzians arising from generation and recombination of free carriers could be distinguished. In addition thermal noise was observed. The generation-recombination noise was found to depend on temperature. Calculations based on the existence of localized states in the tails of the Landau levels were in agreement with the experimentally found Lorentzians. The temperature dependence was explained by a decrease in the number of localized states with increasing temperature. The distance between the mobility edges was found to increase proportionally with temperature. At 4.2 K this distance was estimated to be approximately equal to the width of the Landau level.

Long-distance gigabit-range optical fiber transmission experiments employing DFB-LD's and InGaAs-APD's

High-speed and long-distance transmission characteristics have been examined at 1.2, 2, and 4 Gbit/s, employing mesa structure DFB-DC-PBH LD transmitters and planar InGaAs APD receivers. High receiver sensitivities, -40 dBm at 1.2 Gbit/s, -37.4 dBm at 2 Gbit/s and -32.4 dBm at 4 Gbit/s, have been obtained employing high-speed and low noise InGaAs APD/FET receiver circuits. Long-span transmissions, 1.2-Gbit/s 170-km, 2-Gbit/s 141-km, and 4- Gbit/s 120-km at 1.55 μm, and 4-Gbit/s 74-km at 1.3 μm, have been performed. Power penalties caused by the LD wavelength chirping in the 1.5- μm wavelength region and error rate flooring caused by the LD side-mode oscillation in the 1.3- μm wavelength region are discussed. The transmission length is limited not only by the DFB LD wavelength chirping but also by the two-mode oscillation, which was observed at the pulse leading edge when LD bias current was near the threshold current. From the 1.3 μm wavelength 4-Gbit/s experiment, it was found that the pattern effect of the side-mode oscillation caused the error rate floor, when the LD bias current is set near the threshold current, and that the error rate floor disappeared when the bias current is set slightly above the threshold.

1/f noise in GaAs: Evidence of a new scale invariance.

Low-frequency noise measurements were made in the temperature range of 77-340 K on submicrometer resistors made from GaAs grown by molecular-beam epitaxy. Two types of noise were found, depending on surface treatment. One type consisted of discrete spectral components which showed no anomalous statistical behavior. The other type was a small $\frac{1}{f}$ component which showed anomalously large variations in spectral density, with these variations themselves having a $\frac{1}{f}$ spectrum.

Design and performance of compact low noise GaAs MESFET amplifiers for UHF operation

The design considerations and experimental results of compact low noise GaAs MESFET Amplifiers for UHF operation are described in this paper. The miniaturized and optimized circuits are obtained by means of special matching network and CAD technique. Both a two-stage unit at 700 MHz and a three-stage unit at 1000 MHz are fabricated on a 50×60 mm2 alumina substrate, and power gain of 29 dB and 30 dB, noise figure of 0.8 and 1.2 dB and bandwidth of 40 MHz (3 dB) and 100 MHz (1 dB) are obtained respectively. The satellite direct broadcasting TV receiver fabricated with a 700 MHz GaAs MESFET amplifier has clear pictures and good sound.

Process‐Induced Leakage Current in a Low Noise GaAs MESFET

The cause of a process‐induced leakage current in low noise MESFET's has been traced to conduction along the semi‐insulating buffer surface surrounding the mesas that contain the active elements of the device. The ion milling process, which we used to define the mesas, is responsible for inducing large, variable increases in surface leakage. For a fixed voltage between the gate and source pads of 1V the induced leakage current ranged from 5 nA to 10 μA at 23°C. We compared the effects of several commonly used etches for cleaning . A buffered peroxide solution did not reduce the induced leakage current. By contrast, a concentrated aqueous solution reproducibly reduced the induced leakage current to below 1 nA. Auger analysis revealed a correlation between high surface leakage and the presence of a surface Ga oxide layer. We were unable to definitively identify the cause of the leakage, but suggest two possible mechanisms that are consistent with our data: (i) band bending due to charges in the surface oxide, or surface state effects, and (ii) conduction through a thin layer of elemental As located between the surface oxide and the .

Optimization of ion-implanted low noise GaAs metal-semiconductor field effect transistors

This paper presents an investigation of the effects of implantation energy and dose on the noise figure and associated gain of low noise GaAs metal-semiconductor field effect transistors. Our results show that the noise figure and associated gain in these devices decrease as the implantation energy and the implanted dose increase. rf and dc performance of devices fabricated by direct ion implantation into liquid encapsulated Czochralski substrates, metalorganic chemical vapor deposited buffer layers, and AsCl3 buffer layers have been evaluated. The equivalent circuit elements derived from the S parameters are used to interpret the variation of critical device properties as a function of implantation energy, dose, and gate recess depth.

30 GHz Band Low Noise Receiver for 30/20 GHz Single-Conversion Transponder

This paper describes the design and performance of a low noise multicarrier receiver for a 30/20 GHz single-conversion satellite transponder. To develop a low noise receiver the following areas were examined: 1) analysis of spurious signals, 2) selection of devices most suitable for use on board the satellite, and 3) level diagram tradeoff studies. The receiver consists of a 30 GHz low noise GaAs FET amplifier, a 30/20 GHz GaAs Schottky barrier diode mixer, a dielectric resonated local oscillator, a 20 GHz high gain GaAs FET amplifier, and a 20 GHz high power (0.5 W) GaAs FET amplifier. The receiver has an 8 dB noise figure and a 48 dB gain in the frequency range from 28.395 GHz to 29.015 GHz (620 MHz frequency bandwidth).

High performance ion-implanted low noise GaAs MESFET's

Low noise GaAs MESFET's fabricated by ion-implanting into AsCl 3 VPE buffer layers have demonstrated not only excellent dc and RF performance, but also a highly reproducible process. The average noise figure and associated gain of four device lots at 12 GHz are 1.6 dB and 10.0 dB, respectively. The standard deviation of noise figure and associated gain from device lot to lot are 0.03 dB and 0.19 dB, respectively. And the standard deviation of noise figure and associated gain from device to device for 35 devices over four lots are 0.13 dB and 0.47dB, respectively. The best device performance includes a 1.25 dB noise figure with 10.46 dB associated gain at 12 GHz for a 0.5 µm × 300 µm FET structure. These results demonstrate the excellent performance and process consistency of ion implanted MESFET's.

Low noise GaAs metal-semiconductor field-effect transistor made by ion implantation

Low noise GaAs metal-semiconductor field-effect transitors (MESFET’s) have been made by direct ion implantation into high pressure liquid encapsulated Czochralski (HPLEC) undoped substrates and unintentionally doped high resistivity buffer layers. A noise figure of 1.3 dB with 10.3-dB associated gain has been achieved at 12 GHz, and a 2.2-dB noise figure with 7.4-dB associated gain has been measured at 18 GHz with a 0.6-μm gate length by 300-μm gate width FET device, fabricated from a HPLEC undoped substrate. Comparable dc and rf performance has also been achieved for devices fabricated from undoped buffer layers. Equivalent circuit elements have been evaluated in an effort to understand the critical parameters necessary to achieve these results.

GaAs FET Failure Mechanisms Due to High Humidity and Ionic Contamination

Failure mechanisms resulting from the concurrent exposure to high relative humidity, ion contamination, and temperature cycling were studied in commercially available, low noise GaAs fieldeffect transistors (FETs). This type of device will be applied in such adverse environmental conditions. Devices with Al and Au/refractory gates from four different suppliers were studied. Au/refractory gate devices were less susceptible to degradation as a result of the hostile environment. Failure mechanisms were determined and correlated with the electrical degradation of the devices.

Low noise GaAs varactor and mixer diodes prepared by molecular beam epitaxy

Schottky-barrier varactor and mixer diodes have been made from Ge-doped GaAs layers grown by molecular beam epitaxy. A microstrip parametric amplifier circuit incorporating a hyperabrupt varactor diode has given a noise temperature of 120 K and bandwidth of 180 MHz at 15 dB gain when pumped at 34 GHz, and a mixer diode mounted in a cryogenic receiver circuit had an s.s.b. noise temperature of 180 K at 90 GHz.

Radiation Effects on GaAs MESFETs

The effect of fast neutron and gamma radiation on the electrical characteristics of commercial 1 ?m and 4 ?m low noise GaAs MESFET has been evaluated. The change in the microwave scattering parameters at 2 to 4 GHz (S-band), 1 MHz equivalent circuit parameters, DC characteristics and low frequency input noise equivalent voltage from 2 KHz to 1.5 MHz was determined at neutron fluences between 5 × 1013 to 8 × 1014 n/cm2 and gamma doses of up to 8 × 107 rads (Si). These radiation induced changes are described and causes for these changes are discussed.

Effect of neutron and gamma irradiation on the low-frequency noise in GaAs m.e.s.f.e.t.s

Low-frequency noise in GaAs m.e.s.f.e.t.s has been measured from 2 kHz to 1.5 MHz as a function of fast neutron fluence and gamma dose. From 5 × 1013 to 8 × 1014 n/cm2, the noise increases appreciably, with the noise enhancement from 2 to 10 kHz attributed to generation-recombination noise in the gate depletion layer and from 500 kHz to 1.5 MHz to channel trapping effects. There was comparably little change with gamma irradiation up to doses above 107 rad (Si).

Erratum: Effect of neutron and gamma irradiation on the low-frequency noise in GaAs m.e.s.f.e.t.s

Low-frequency noise in GaAs m.e.s.f.e.t.s has been measured from 2 kHz to 1.5 MHz as a function of fast neutron fluence and gamma dose. From 5 × 1013 to 8 × 1014 n/cm2, the noise increases appreciably, with the noise enhancement from 2 to 10 kHz attributed to generation-recombination noise in the gate depletion layer and from 500 kHz to 1.5 MHz to channel trapping effects. There was comparably little change with gamma irradiation up to doses above 107 rad (Si).

100K uncooled GaAs m.e.s.f.e.t. amplifier as paramp replacement

The characterisation, design and realisation of a low noise GaAs m.e.s.f.e.t. amplifier to replace a narrow band parametric amplifier at 1.7 GHz is described. Special measurement and analytical techniques are necessary owing to the high reflection coefficients and conditional stability of the transistor, as well as the very low noise figures being measured. A single stage amplifier is realised with a noise figure of 1.25 dB and 13.5 dB associated gain at 1.7 GHz.

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/f T . 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.

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.

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 frequence prenant naissance dans le canal des f.e.t. a l'arseniure de gallium pour des frequences allant de 10 Hz a 0. 5 MHz et une temperature comprise entre −120 et +21 °C. Nous avons mis en evidence que pour de faibles puissances dissipees les sources de bruit principales a basse temperature ont pour origine des phenomenes de diffusion et de generation recombinaison.