In this work we have determined a nonlinear electrothermal model for a low-noise GaAs MESFET, which enables evaluation of the time dependance of the internal temperature rise consecutive to a microwave overload impinging on the gate. This model takes into account the balance between the microwave energy loss under the gate in the active layer and energy conduction through the substrate during the pulse duration. We have conducted experimental determination of the critical peak power level for failure for several pulse durations and with the application of the model, we find that burnout is reached when the internal temperature is exceeding 500 degrees C, We are able to predict the vulnerability of a low-noise amplifier under microwave overload.

Doppler Lidar is a good candidate for wind velocity measurement. But the total Doppler shift experienced by the backscattered laser pulses with a conical scanning instrument varies in a wide frequency range. Narrowing intermediate frequency bandwidth could provide better performances for both detection and low noise amplification. Therefore, optical mixing and parametric amplification in the same device have been investigated with HgCdTe photodetectors cooled at liquid nitrogen temperature. The optical and microwave setup needed for simulating Doppler and testing these detectors is described. Some experimental results, which demonstrate the feasibility of this new heterodyning process, are given. (C) 1995 John Wiley & Sons, Inc.

For electrical homogeneity assessment of implanted layers and temperature evaluation of sidegating effect, we have designed a cryogenic mapping prober. Mapping of electrical parameters over a wafer is possible at any temperature from 100 to 400 K. When specific test patterns are available, a magnetic field, normally to the wafer plane, provides Hall effect mapping in the same temperature range. We find a temperature dependence of sidegating effect on GaAs implanted substrates, which increases sharply around 225 K. We did not find any correlation between sidegating amplitude and sidegating current. Hall effect mapping has been done on ion implanted InP substrates at 100 and 300 K; the shift of transport properties is discussed.

Knowledge of the electrical activity of an implanted layer throughout wholly semi-insulating indium phosphide (InP) crystals provides a very useful indication of the crystal qualification for integrated circuit application. Different cartography techniques are studied to characterize various SI InP ingots: The mapping of sheet resistance and the scanning photoluminescence image are mainly performed. Standard iron doped SI InP crystals grown by LEC are used, as well as iron–gallium doped crystals and long annealed iron-doped crystals. Cartography techniques as well as different SI ingots are compared.

Be doped In x Ga 1-x As epitaxial layers, with concentration level from 10 16 to 5x10 19 at/cm 3 , have been grown lattice matched on InP substrate by molecular beam epitaxy. Room temperature Hall effect measurements, indicate low mobility for P type samples while for low Be doping the conduction can be N type. Secondary Ion Mass Spectroscopy analysis shows that the electrical behavior is linked to the oxygen to beryllium concentration ratio in the layer. The temperature Hall effect measurements show that a surface or an interface N type layer can be created, depending on the oxygen to beryllium ratio concentration and is responsible for the apparent low Hall mobilities Des couches epitaxiales In x Ga 1-x As, elaborees en accord parametrique sur substrat InP par la technique d'epitaxie par jets moleculaires ont ete dopees avec du beryllium de 10 16 a 5x10 19 at/cm 3 . D'apres les mesures electriques, les couches de type P sont fortement compensees et a faible niveau de dopage la conductivite peut etre de type N. Les analyses d'impuretes par sonde ionique montrent que l'oxygene est responsable de ce comportement. Les mesures d'effet Hall, en fonction de la temperature, ont montre que suivant le niveau d'oxygene, il pouvait exister une zone N en surface ou a l'interface avec le substrat InP semiisolant, responsable des faibles mobilites de Hall mesurees

InGaAs epitaxial layers have been doped with beryllium with concentrations ranging from 1016 to 5×1019 cm−3 as measured by secondary ion mass spectroscopy (SIMS). From electrical measurements we have observed that p-type layers presented a high degree of compensation, and for a doping level below 5×10−7 cm−3, they are often found to be n type. SIMS analysis shows that oxygen is responsible for such behavior. Beryllium doping leads to incorporation of a large amount of oxygen in the epitaxial layers. Investigations on the origin of oxygen incorporation show that it is extremely sensitive to the residual vacuum during the growth and can be reduced by decreasing arsenic pressure.

Electrical measurements during the thermal recovery of fast neutron irradiated GaAs confirm the main steps around 400 and 600 °C, corresponding to the decay of electron paramagnetic resonance identified V2−Ga and As4+Ga centers.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not.The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Caractérisation de l'interface couche implantée substrat semi-isolant LEC GaAs

Due to its high potential technological interest, semi-insulating GaAs has been a material extensively studied for some years. Nevertheless the published results and conclusions are scattered ; comparisons between the various data in litterature are often very risky because of the diversified nature of samples and preparations and also of the diversity of experimental set up used. This paper reports a set of coherent experimental measurements performed on two typical ingots. The first one is grown by horizontal Bridgman method with Cr and Ga2O3 added in the melt ; the second one is grown (undoped) by liquid encapsulated (B2O3) Czochralski method. The numbered samples were analysed following various physical, optical or electrical technics by different laboratories. Results and conclusions reported here show a good consistancy. Chemical and crystalline homogeneity are especially studied ; the role of chromium doping is also discussed. It is hop ed that this work will help the understanding of GaAs.

In p-type silicon the electrically active impurity concentration is measured by Hall mobility and Hall constant temperature dependence analysis. The results obtained on a large resistivity range are compared with other physical methods. The importance is shown of the anisotropy of the free carrier scattering by phonons on the analysis of experimental results. Nous avons déterminé le contenu en impuretés électriquement actives d'échantillons de Silicium de type p à partir des mesures de mobilité de Hall et de la constante de Hall en fonction de la température. Les résultats obtenus sur un large domaine de résistivité sont comparés à d'autres méthodes physicochimiques. Nous mettons en évidence l'importance de l'anisotropie de la diffusion des porteus libres par les phonons sur l'interprétation des résultats expérimentaux.

Die elektrisch aktiven Verunreinigungen, Donatoren, Akzeptoren und Haftstellen, sollten bestimmet werden. Zwei verschiedene Proben werden untersucht. (1) Stark mit Phosphor dotierte und durch Aluminium kompensierte Proben: Hier ergab sich ein Beitrag zur Leitfähigkeit von einem Störband. Die Hallkonstante hat einen Maximalwert bei einer Temperatur, die von der Dotierung und dem Kompensationsgrad der Probe abhängt. Leicht dotierte Proben, die mit 600 keV-Elektronen bestrahlt waren: Mit Hilfe der Methode der kleinsten quadratischen Abweichung wurden die experimentellen Daten angepaßt und die gewünschten physikalischen Parameter einschließlich deren Fehlerabschätzung bestimmt. Auf diese Weise wurden gleichzeitig die Donator- und Akzeptorkonzentration sowie die Aktivierungserergie für den tiefen Energiezustand und die Transportparameter für das Störband ermittelt. Bei kommerziell erhältlichen n -Typ Silizium mit einem spez. Widerstand von 10 Ω. cm ergab sich eine starke Kompensation mit Aluminium.

Impurity heterogeneity has been studied along a nearly compensated silicon crystal. The doping impurities were phosphorus and aluminium. The validity of quantitative measurements on the whole sample (such as Hall effect, mass spectrometry, nuclear activation) have been checked by qualitative methods of microobservation (X-ray microprobe, electron microscopy). A theoretical model has been set up which tentatively explains why impurities may precipitate in different ways. Les auteurs ont étudié l'inhomogénéité de répartition du phosphore et de l'aluminium introduits simultanément dans du silicium. Les measures quantitatives, mais moyennant, sur tout l'échantillon (effet Hall, spectrométrie de masse, analyse par activation) ont été testées par des méthodes microanalytiques mais qualitatives (sonde de Castaing, microscope électronique). Une tentative a été faite pour expliquer pourquoi les impuretés peuvent précipiter de différentes manières.

Le but de cette étude a été de mesurer des concentrationms en impuretés électriquement actives, donneurs, accepteurs, pièges du Silicium de type n.