Electronic transport and metastabilities in P-doped a-Si:H

Agarwal, Pramod; Agarwal, S. C.

doi:10.1063/1.364152

Cited by 20 publications

(17 citation statements)

References 14 publications

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“…A rapid thermal quenching increases DC in porous silicon (this work). Similar increase in dark current upon fast quenching was observed in doped a-Si:H by various authors [13,14,15]. Although the effect of LS and thermal quenching in PS are qualitatively similar to those reported for aSi:H, a closer look shows differences between the two.…”

Section: Takes Over and We See A Net Increase In Dangling Bonds (Esupporting

confidence: 85%

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Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

Mandal¹,

Awasthi²,

Konar³

et al. 2009

Philosophical Magazine

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International audienceWe observe that light soaking for short durations and thermal quenching in nanocrystalline porous silicon (PS) produce metastable states. These metastable states show higher dark current, higher and photo current, large photoluminescence and weaker electron spin resonance (ESR) signal. However, long exposures to light produce opposite effect. The metastable states are stable against sub band gap light exposures. These metastable states can be removed by annealing at 150 0C for 1 hour. ESR shows the presence of a-Si phase (g~2.0058, 6.4G) in PS sample, but it is not sufficient to explain all experimental results. Rather, our experiments suggest that light soaking causes more than one type of defects in porous silicon. The structural changes involving the movement of hydrogen present at the surface of PS or at PS/a-Si interface may be responsible for these effects

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Section: Takes Over and We See A Net Increase In Dangling Bonds (Esupporting

confidence: 85%

“…Fast thermal quenching (FQ) from 450K to room temperature also gives an increase in DC, PC and PL and a decrease in ESR signal. Though the increase in DC after fast cooling and short exposures in case of PS is similar to PPC that was observed in doped aSi:H, no decrease in ESR has so far been reported for undoped a-Si:H [13,14,15].…”

supporting

confidence: 67%

Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

Mandal¹,

Awasthi²,

Konar³

et al. 2009

Philosophical Magazine

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“…We ® nd that LS results in a large change in Q, whereas FQ leaves it nearly unchanged. These results are in qualitative agreement with the data for a-Si : H(P) (Hauschildt et al 1982, Agarwal andAgarwal 1997). Isothermal relaxation studies have also been made.…”

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confidence: 90%

Thermal equilibrium, the Staebler-Wronski effect and potential fluctuations in lithium-doped hydrogenated amorphous silicon

Agarwal¹

2000

Philosophical Magazine B

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We report the e ect of fast thermal quenching (FQ) and light soaking (LS) on electronic transport in lithium-doped hydrogenated amorphous silicon (aSi : H(Li)), and compare the two instabilities in the same specimen. We ® nd that the metastable changes are qualitatively similar to those in phosphorusdoped hydrogenated amorphous silicon. The ® lms are in thermal equilibrium above the temperature T E , which is lower for heavier doping. However, for a given sample, the T E values are about the same for FQ and LS. Isothermal relaxation of conductivity ¼ of the metastable states follows a stretched exponential, but the relaxation parameters for FQ and LS are di erent. We also ® nd that the function Qˆln ¼ ¡ eS =k shows a large change after LS but hardly changes after FQ. The results are explained by assuming that the recombination of carriers at the local minima of the potential¯uctuations present on a-Si : H(Li) gives rise to structural changes. The observed increase in the slope of Q versus 1=T after LS is interpreted as an increase in potential uctuations. The very small change in Q observed after FQ is explained in terms of the higher mobility of hydrogen at the high temperature from which a-Si : H is quenched.

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“…The slope of thermo emf ( V) vs. temperature difference ( T) gives the thermopower (S). All measurements were done in ∼1 torr helium atmosphere to ensure good thermal contact between the sample and the thermocouples 20 …”

Section: Experimental Arrangement For Measuring Lrpfmentioning

confidence: 99%

Light induced degradation of amorphous silicon containing nanocrystalline silicon

2014

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The effect of light soaking (LS) is studied in hydrogenated amorphous silicon (a-Si:H) containing different amounts of nanocrystals, prepared by varying the deposition conditions in a plasma enhanced chemical vapor deposition (PECVD) system. We find that the presence of nanocrystals (nc-Si) stabilizes the a-Si:H against LS. The long range potential fluctuations (LRPF) are measured and we find that they become smaller as the fraction of nanocrystals (χ) in the films increases. Raman spectra show a peak at 490 cm−1, which is taken to be the result of Intermediate Range Order (IRO) in the films. This IRO peak appears just when the hydrogen dilution is sufficiently high for the crystallization to begin, and increases with increasing hydrogen dilution as the crystallization increases. In contrast LRPF have maximum width when χ is zero and it decreases as χ increases. Further, the degradation upon LS is negligible when χ > 25%. We suggest an alternative mechanism for the improved stability, in which the photogenerated carriers moving under the influence of the long range potential fluctuations have a propensity to go to nc-Si, and recombine in that region.

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Electronic transport and metastabilities in P-doped a-Si:H

Cited by 20 publications

References 14 publications

Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

Light and thermally induced metastabilities in electrochemically etched nanocrystalline porous silicon

Thermal equilibrium, the Staebler-Wronski effect and potential fluctuations in lithium-doped hydrogenated amorphous silicon

Light induced degradation of amorphous silicon containing nanocrystalline silicon

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