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The present paper reports on high frequency In0.49Ga0.51P/GaAs HBTs and high speed lightwave communication circuits using a novel planar self-aligned fabrication process based on chemical beam epitaxial (CBE) selective regrowtlh of both the extrinsic base and subcollector layers. Using this process, a current gain of 43 and cutoff frequencies of 50 and 70 GHz for fT and fMAX respectively, have been...
Demand for temperature resistant semiconductor and circuit operation has reached significant levels in recent years. This paper describes the results of numerical simulation used to study the high temperature operation of heterojunction transistors incorporating wider band gap Gallium Nitride layers. Orders of magnitude reduction in drain an gate leakage current have been demonstrated over conventional...
In this paper we present the results of RF and noise measurements on MESFETs transplanted by epitaxial lift off (ELO). ELO is a technology by which epitaxially grown layers are lifted off from their growth substrate and are subsequently re-attached to a new host substrate. [1,2]. Gate leakage current as well as noise and RF characteristics of MESFETs and GaAs circuits are compared before and after...
The electrical source-drain breakdown mechanism of pseudomorphic (PM) HEMTs has been studied in a pulse and DC regimes. It has been revealed that a maximum drain voltage is limited by an avalanche injection breakdown of the undoped i-GaAs layer (buffer). It has been established that observed breakdown is the result of the mutual intensification of an avalanche generation rate near the drain and an...
The problem of calculation of stresses in the strained layer stripes is simplified if attention is confined to the middle of the surface layer of the stripes. In this region the vertical component of the stress and the shear components of the stresses and strains are zero and the strain component ??yy (parallel to the length of the stripe) is known in the stripe coordinates. Hooke's equation is first...
Thermal degradation mechanisms of the GaAs MESFETs have been studied using FATFET(Lg=50??, Wg= 200??m) with thermal step stress and accelerated life tests. The I-V and C-V characteristics of the devices were measured after every thermal step. AES, XRD and cross-sectional TEM were also used to analyze the thermal degradation mechanisms. The activation energy for thermal degradation of the Schottky...
A simple model is proposed to monitor the dc current gain long-term instability in the AlGaAs/GaAs heterojunction bipolar transistor (HBT). It is derived from the theory that the recombination current at the extrinsic base surface increases with time due to the surface degradation process. Furthermore, the initial 1/f noise and base leakage current characteristics have been used to provide the needed...
The potential of the HEMT as microwave and millimetre wave MMIC switch is investigated. Therefore, we determine a suitable small-signal model to represent both switching states. This enables us to interpret the HEMT switch performance in terms of layer structures and layout parameters. This analysis shows that HEMTs are useful MMIC switch candidates due to their low Ron at a relatively small gate...
It is believed that significant velocity overshoot effects are responsible for the high performance of Pseudomorphic HEMTs (PsHEMTs) with InGaAs channels grown on GaAs substrates. The expected overshoot is associated with the low effective mass in the channel and the large ?? - L separation and is clearly demonstrated in numerous Monte Carlo simulations. Average electron velocities well in excess...
Resonant tunnelling tlhrough virtual states in a wide pseudo-quanttum well is observed at liquid He temperature. This well is formed in the spacer layer region (n--GaAs) of a single barrier heterostructure n+-GaAs/n--GaAs/AIAs/n--GaAs/n+-GaAs due to the electron reflection from the main barrier at one side and from the smooth potential drop through the n-/n+ junction in the GaAs at the other side...
The effect of random fluctuations of the donor density in the quantum well of an intersubband single quantum-well infrared phototransistor (QWIPT) with triangular emitter and collector barriers is studied theoretically. It is shown that the fluctuations of the donor distribution in the plane of the QW can significantly increase the dark current. It reduces the photocurrent-to-dark ratio and detectivity.
III/V ICs and especially GaAs ICs based on submicron gate MESFETs are an established industrial technology used in commercial applications like high-end computers, L-band mobile phones, X band satellite TV receivers, K-band radio links and 2.5 Gb/s optical links. In the meanwhile advanced processes based on 0.2-0.1 ??m PHEMTs as well as submicron HBTs on GaAs or InP substrates are being developed...
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