Abstract
Luminescence decay with time often shows a power-law dependence of the
form intensity I ∝ t−k, where t is time and k is usually in the range 1–1.5.
It is shown here that this power law can result from the tunnelling of trapped
electrons to recombination centres that are randomly distributed, and that the
range of exponents matches that of the observations. The explanation accounts
for the most extreme case of an observed t−1.06 dependence extending over nine
decades of time.