Photo-enhanced response of hopping bolometers for detection of particles and non-equilibrium phonons

Using a heat pulse technique we have observed that the sensitivity of a GaAs:Zn bolometer operating in the hopping regime is significantly enhanced by illumination with white light. However, the enhancement cannot be understood simply in terms of the steady-state photoconductive change in resistivity varying as T1/4 exp(T0/T)1/4 with temperature. We propose that the primary consequence of illumination is the population of excited states of the Zn acceptors between which non-equilibrium, and therefore higher frequency, phonon-assisted tunnelling is more effective than normal hopping.