Enhancement by electric field of high-speed photoconductivity in AlGaN∕GaN heterostructures

The authors report a large response in the conductivity of AlGaN∕GaN heterostructures to a 10ns UV laser pulses. The dynamics of the conductivity response follows the time evolution of the laser pulse. This fast photoconductivity component shows a remarkable enhancement in high electric fields. For the field ≈15kV∕cm, it increases by at least one order of magnitude at temperatures of 4.2 and 300K. This photoconductivity enhancement is found to be related to the hot electron effect. The authors propose an explanation for the observed phenomena. The mechanism of the photoconductivity enhancement involves nonequilibrium LO phonons generated by hot carriers.