Comparison of the potential fluctuations in a-Si:H measured by the optical and transport methods

Abstract

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Potential fluctuations in disordered semiconductors measured by transport and optical methods

“…Optical absorption was also measured in the same samples of doped a-Si:H [1]. The data for the absorption coefficient α can well be fitted by the Urbach formula 0 0…”

“…Recently a comprehensive experimental study of transport phenomena and of the optical absorption in hydrogenated doped amorphous silicon (a-Si:H) was carried out [1]. The results were interpreted in the framework of the theories exploiting random potential fluctuations caused by the random spatial distribution of impurity atoms in the host semiconductor matrix.…”

“…Using this equation and measured values of E α one obtains for 0 V estimates of about 1 eV, which is more than an order of magnitude higher than the estimate for 0 V obtained from the measurements of the drift mobility in the same samples. This puzzle was recently raised as a challenging problem in the field of doped amorphous semiconductors [1]. The suggested solution was based on the assumption that the disorder potential limiting transport differs from that limiting the light absorption [1].…”

“…This puzzle was recently raised as a challenging problem in the field of doped amorphous semiconductors [1]. The suggested solution was based on the assumption that the disorder potential limiting transport differs from that limiting the light absorption [1]. We try to resolve this puzzle on another basis, namely, by analysing the relation between E α and 0 V using the theory of Shklovskii and Efros for light absorption [2,5], which drastically differs from that of John et al [4].…”

Influence of heterogeneities on the electronic properties of hydrogenated amorphous silicon

“…None the less, measuring conductivity and thermo power and the monitoring of the slope E Q of the function Q may help in estimating them qualitatively. Further, the measurement of α CPM and α PDS and treating them as the optical analogues of transport (σ and S) might give more insight [52]. But the theory has been worked out only qualitatively [53].…”