Figure 4. TOF signal from a-Se/PI device structure demonstrating the device is capable of reaching avalanche regime.

(a) Device biased at an electric field below avalanche regime. (b) Device biased at an electric field in avalanche regime. The voltage in parentheses refers to the bias voltage across the device, E refers to the energy of the laser pulse measured by the energy meter and Attn. refers to the attenuator transmission (see Fig. 3). The ringing in the measured results is from reflections caused by improper impedance matching.