J. Phys. Colloques
Volume 42, Numéro C4, Octobre 1981Proceedings of the Ninth International Conference on Amorphous and Liquid Semiconductors
|Page(s)||C4-547 - C4-550|
J. Phys. Colloques 42 (1981) C4-547-C4-550
RECOMBINATION IN DISORDERED SOLIDSH. Scher
Xerox Webster Research Center, Webster, New York 14580, U.S.A.
The main point of this article is to present a simple physical picture of the recombination process of a carrier hopping in a disordered solid in the presence of molecular recombination centers (rc). First, an exact (asymptotic) calculation of the entire time dependence of the transient photocurrent (TP) and the number of surviving carriers n(t) is carried out for a suitable model system. It is shown that the t-(1-α) → t-(1+α) transition does exist in the TP however the transition occurs in over two decades in time (for α=0.5). Further, the time tr corresponding to the intersection of the two slopes in the log(TP)-log(t) plot is the same as the median time for the n(t) decay. The tr is next shown to have an alternate simple interpretation. In the low rc concentration limit, tr is determined from a calculation of the number of distinct sites visited by the hopping carrier, as a function of time (t) and electric field (E). The results are compared to recent measurements in a-Si : H.