Transient analysis of p-n-p-n optoelectronic devices

p-n-p-n optoelectronic devices were analyzed using a coupled junction model, an equivalent circuit model, and a physical model. The accuracy of these models was confirmed by comparison with experimental data. The result of the authors´ analysis was a new understanding of the dynamic properties of p-n-p-n devices. The authors found that the onset of switching depends only on the voltage across the forward-biased outer junctions, not on the total applied bias. Turn-on delay is dependent on the rate of voltage change across the outer junctions and the efficiency of the laser emitter. Fast turn-off of two-terminal devices is theoretically possible by applying a reverse bias during the turn-off transient. dV/dt induced switching can be avoided by proper design. Based on the authors´ models, the maximum large-signal operating frequency of two-terminal p-n-p-n devices was estimated to be ~240 MHz