Imaging of high field regions in semi-insulating GaAs under bias

Berwick, Kevin; Brozel, M.R.; Buttar, C. M.; Cowperthwaite, M.; Sellin, P.J.; Hou, Yaonan

doi:10.1016/0921-5107(94)90111-2

Cited by 34 publications

(30 citation statements)

References 3 publications

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“…The dramatic increase in electroncapture cross section was seen as preventing significantly higher fields from existing in the sample since any ionized EL2 centers would tend to neutralize quickly at higher fields. 11 Berwick et al, 12 and more recently Castaldini et al, 13 measured the electric-field profile of a semiinsulating GaAs radiation detector directly using the scanning surface potential technique. Their data clearly showed that the electric field at the metal-SI GaAs junction does not drop in the linear manner predicted by the depletion approximation, but indeed saturated at ϳ10 kV cm Ϫ1 , and remained approximately constant at this value until after some depth the field dropped to zero.…”

Section: Positron Drift Model With a Saturating Electric Fieldmentioning

confidence: 99%

“…[5][6][7][8][9][10] Positron diffusion in semi-insulating GaAs has previously been investigated by monitoring the fraction of positron drifted back to the metal-GaAs interface under the application of an electric bias. 10 The data, analyzed with the assumption of the depletion approximation, gave a positron mobility of 70 Ϯ10 cm 2 V Ϫ1 s Ϫ1 at 300 K. However, some nonpositron works have recently revealed the failure of the depletion approximation in Au-semi-insulating ͑SI͒ GaAs system, [11][12][13] which report a lower than expected electric field and a more extended depletion region as compared to those predicted within the depletion approximation. McGregor et al 11 attributed this observation to an enhancement of the electroncapture cross section for the EL2 ϩ center at electric fields above some critical value.…”

Section: Introductionmentioning

confidence: 99%

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Electric-field distribution in Au–semi-insulating GaAs contact investigated by positron-lifetime technique

et al. 1999

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Positron-lifetime spectroscopy has been used to investigate the electric-field distribution occurring at the Au-semi-insulating GaAs interface. Positrons implanted from a 22 Na source and drifted back to the interface are detected through their characteristic lifetime at interface traps. The relative intensity of this fraction of interface-trapped positrons reveals that the field strength in the depletion region saturates at applied biases above 50 V, an observation that cannot be reconciled with a simple depletion approximation model. The data, are, however, shown to be fully consistent with recent direct electric-field measurements and the theoretical model proposed by McGregor et al. ͓J. Appl. Phys. 75, 7910 ͑1994͔͒ of an enhanced EL2 ϩ electron-capture cross section above a critical electric field that causes a dramatic reduction of the depletion region's net charge density. Two theoretically derived electric field profiles, together with an experimentally based profile, are used to estimate a positron mobility of ϳ95Ϯ35 cm 2 V Ϫ1 s Ϫ1 under the saturation field. This value is higher than previous experiments would suggest, and reasons for this effect are discussed.

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Section: Positron Drift Model With a Saturating Electric Fieldmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electric-field distribution in Au–semi-insulating GaAs contact investigated by positron-lifetime technique

et al. 1999

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“…Recent experiments [3][4][5][6][7][8][9] that use the electro-optic Pockels effect in order to measure the local electric fields in the sample have opened up the way towards a more detailed quantitative understanding of the domains and the trapping process in SI GaAs. There is a considerable interest in the properties of the EL2 defect because SI GaAs has an increasing relevance, e.g., as a particle detector [10][11][12][13] and for optical data storage. 14 The reader may well wonder why the transport properties of SI GaAs should be of any particular interest.…”

Section: Introductionmentioning

confidence: 99%

Slow domains in semi-insulating GaAs

Neumann

2001

Journal of Applied Physics

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Articles you may be interested inBroadening effects and ergodicity in deep level photothermal spectroscopy of defect states in semi-insulating GaAs: A combined temperature-, pulse-rate-, and time-domain study of defect state kinetics Saturated electric field effect at semi-insulating GaAs-metal junctions studied with a low energy positron beam Semi-insulating GaAs shows current oscillations if a high dc voltage is applied to a sample. These oscillations are caused by traveling high-electric-field domains that are formed as a result of electric-field-enhanced electron trapping. This article describes the various types of experiments that have been carried out with this system, including recent ones that use the electro-optic Pockels effect in order to measure the local electric fields in the sample in a highly accurate manner. An historical overview of the theoretical developments is given and shows that no satisfying theory is currently available. A list of all the required ingredients for a successful theory is provided and the experimental data are explained in a qualitative manner. Furthermore, the main electron trap in semi-insulating GaAs is the native defect EL2, the main properties of which are described.

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“…From the OBIC and surface potential profiles, it is possible to deduce the active layer width W [11,12]. The results, obtained on detectors realized on GaAs material supplied by Hitachi with process RI, are shown in Fig.…”

Section: B Electric Field Profile and Active Region Vs Vmentioning

confidence: 99%

Improved performance of GaAs radiation detectors with low ohmic contacts

Nava

Bertuccio

Vanni

et al. 1997

IEEE Trans. Nucl. Sci.

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Gallium arsenide (GaAs) offers an attractive choice for room temperature X-and y-ray detectors.However performance of SI LEC bulk GaAs detectors is at present limited by the short carrier lifetime and by the diode breakdown occurring as soon as the electric field reaches the back ohmic contact. We have shown [I] that ohmic contacts based on ion implantation allowed us to go far beyond the bias voltage necessary to achieve a fully active detector. However the conventional thermal treatments (850 "C, 30 s) required to anneal the damage induced by ion implantation strongly reduces the charge carrier lifetime in the detector. Alenia S.p.A. has developed two improved processes (RA and RB) which avoid high temperature annealing and the consequent charge carrier lifetime reduction.With the new detectors, in pixel (200x200 pm2) configuration, a charge collection efficiency (cce) of 90 % for 59.5 keV X-rays and a FWHM of 3.35 keV have been achieved at room temperature. These features, thickness, applied voltage, cce and FWHM are suitable for application of GaAs pixel detectors in medical imaging. Results obtained with a particles and X-rays at different temperatures and in a wide range of applied bias in detectors made with standard, implanted and improved processes are presented, compared and discussed.

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Imaging of high field regions in semi-insulating GaAs under bias

Cited by 34 publications

References 3 publications

Electric-field distribution in Au–semi-insulating GaAs contact investigated by positron-lifetime technique

Electric-field distribution in Au–semi-insulating GaAs contact investigated by positron-lifetime technique

Slow domains in semi-insulating GaAs

Improved performance of GaAs radiation detectors with low ohmic contacts

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