What is the real value of diffusion length in GaN?

Yakimov, E. B.

doi:10.1016/j.jallcom.2014.11.229

Cited by 67 publications

(59 citation statements)

References 48 publications

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“…The samples were also characterized by electron beam induced current (EBIC) and microcathodoluminescence (MCL). [27][28][29][30] From the EBIC collection efficiency dependence on accelerating voltage of the electron probe beam, the value of diffusion length L d was calculated. 29,30 Multiple samples of each type were examined, and we report the range of concentrations observed.…”

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confidence: 99%

“…The fitting parameters in the model are thus L d , the metal thickness, and the width of the space charge region determined by the concentration of uncompensated donors N d . 29 The advantage of this approach compared to scanning the SEM beam along the surface of the sample and monitoring the decrease in the EBIC current as a function of the distance of the probing beam to the Schottky barrier edge 29 is that the calculated diffusion lengths values do not depend on the surface recombination velocity and on the probing beam accelerating voltage (i.e., excitation depth). 29 The disadvantage is that the charge carrier generation function has to be calculated (by Monte Carlo modeling 29 ) and there is no simple analytical procedure to extract the L d values from the measured charge collection efficiency.…”

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confidence: 99%

“…These diffusion lengths are related to ambipolar mobility through L d ¼ (slk B T/e) 1/2 , where s ¼ (rv th N t ) is the recombination lifetime determined by the presence of deep traps, l-the ambipolar mobility, k B the Boltzmann constant, e the electronic charge, r the capture cross section, v th the thermal velocity of charge carriers, and N t the concentration of deep traps-recombination centers. 29 Thus, the values of L d 2 give the range of changes of the ls product from sample to sample and, if the mobility changes are not strong, suggest the relative changes of the density of recombination centers. From Table I, we see that the ET2, ET3, and E c -2.3 eV trap concentrations increase after irradiation, and thus, these traps are potential lifetime killers.…”

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confidence: 99%

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Point defect induced degradation of electrical properties of Ga2O3 by 10 MeV proton damage

Polyakov

Smirnov

Shchemerov

et al. 2018

Applied Physics Letters

110

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Deep electron and hole traps in 10 MeV proton irradiated high-quality b-Ga 2 O 3 films grown by Hydride Vapor Phase Epitaxy (HVPE) on bulk b-Ga 2 O 3 substrates were measured by deep level transient spectroscopy with electrical and optical injection, capacitance-voltage profiling in the dark and under monochromatic irradiation, and also electron beam induced current. Proton irradiation caused the diffusion length of charge carriers to decrease from 350-380 lm in unirradiated samples to 190 lm for a fluence of 10 14 cm À2 , and this was correlated with an increase in density of hole traps with optical ionization threshold energy near 2.3 eV. These defects most likely determine the recombination lifetime in HVPE b-Ga 2 O 3 epilayers. Electron traps at E c-0.75 eV and E c-1.2 eV present in as-grown samples increase in the concentration after irradiation and suggest that these centers involve native point defects.

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confidence: 99%

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Point defect induced degradation of electrical properties of Ga2O3 by 10 MeV proton damage

Polyakov

Smirnov

Shchemerov

et al. 2018

Applied Physics Letters

110

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“…15 While such an approximation is convenient to use, the exponential decay is often inaccurate near the dislocation core, can lead to inaccurate estimates of the diffusion length, and precludes further effort in understanding dislocations. 16 Even with the use of realistic values of recombination strengths in this study, it was not feasible to identify the values of and uniquely due to experimental uncertainties. Thus, the value of was assumed to be constant and equal to 1 nm as has been done previously.…”

Section: Estimating Diffusion Lengths and The Dislocation Recombinmentioning

confidence: 93%

Recombination activity of threading dislocations in GaInP influenced by growth temperature

Mukherjee

Reilly

Callahan

et al. 2018

Journal of Applied Physics

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Room-temperature non-radiative recombination is studied at single dislocations in Ga0.5In0.5P quantum wells grown on metamorphic templates using cathodoluminescence and electron channeling contrast imaging. An analysis of the light emission intensity profiles around single dislocations reveals that the average recombination strength of a dislocation decreases by a factor of four and seven as a result of decreasing the growth temperature of the GaInP quantum well from 725 to 675 and 625 °C respectively. This reduction occurs despite little change in the diffusion length, precluding the prospect of inducing carrier localization by ordering and phase separation in GaInP at lower growth temperatures. These observations are rationalized by the premise that point defects or impurities are largely responsible for the recombination activity of dislocations, and the extent of decoration of the dislocation core decreases with temperature. Preliminary evidence for the impact of the Burgers vector is also presented. The lowest growth temperature, however, negatively impacts light emission away from dislocations. Carrier recombination in the bulk and at dislocations need to be considered together for metamorphic devices, and this work can lead to new techniques to limit non-radiative recombination.2

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“…Since the dark spots in the CL image appear in the same location of the corresponding EBIC image, they are not caused by carrier escape from the junction but rather non-radiative recombination at defects, possibly clusters of point defects in the MQW region. Other examples for EBIC include the investigation of grain boundaries in silicon [71], stacking faults in 4H-SiC [75], measurement of the diffusion length in GaN [76,77] and -Ga2O3 [78], recombination behaviour of dislocations in bulk GaN [79] and solar cells [80].…”

Section: Electron Beam Induced Currentmentioning

confidence: 99%