IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

The power-law dependence of photoconductivity on light intensity is generally taken as evidence for the density of states in the gap to be given by an exponential distribution. We have computed the photoconductivity for some nonexponential distributions of gap states. We show that neither the intensity dependence of photoconductivity nor the temperature dependence of the exponent can be used as evidence for an exponential gap-state distribution. An examination of the results of photoconductivity and space-charge-limited current on a-Si:H suggests that the distribution of gap states is not exponential as is commonly assumed. © 1983 The American Physical Society.