Nonlinearities in Excitonic Luminescence of Direct‐Gap Semiconductors under Very Low Optical Excitation Levels

Abstract

increases gradually with the decrease of I,,, and also becomes higher with increasing of temperat'ure. Linearity ( y = 1) is sometimes observed only a t sufficiently high I,,, above 10l6 quanta x x s-l. A phenomenological theoretical model is proposed which accounts for non-radiative surface recombination and non-uniform spatial distribution of the excited carriers and provides satisfactory qualitative agreement with the experimental findings.

Experimental Studies of the Recombination Processes in Ii-Vi Semiconductors (Bulk Crystals and Epilayers) at Variable Excitation Levels

“…Within certain ranges of I exc these dependencies are well approximated by a power law: I lum ∝ (I exc ) γ with γ < 2. In principle, this type of behaviour is obtained (for excitonic bands) in the analytical [22] and in the numerical [23] theoretical calculations as well. Without going into too much details we may note that the obtained experimental results could become helpful when composing the underlying sets of rate equations.…”

“…This is evident from figure 4a and -more clearly -from figure 4b where the experimental dependencies I lum =f(I exc ) (following the averaging and smoothing) are presented. Details on the measurements and on the pre-processing algorithm can be found in [22]). Within certain ranges of I exc these dependencies are well approximated by a power law: I lum ∝ (I exc ) γ with γ < 2.…”