| The response delay of fast avalanche photoconducting switches is investigated first for the one-dimensional p-i-n model which includes the electron and hole continuity equations solved in the time domain by the explicit finite difference method. No response delay is found. Then the two concentric spheres model is investigated by solving Maxwell's two curl equations plus the continuity equation. This model gives us a clue as to why the delay can happen. Finally, we consider a more realistic model consisting of two parallel circular metal disks on the ends of a cylinder of insulating material. For this model Maxwell's equations are solved by the alternating direction implicit method, and the continuity equations are solved by the explicit finite difference method. This model can explain the response delay. In addition we obtain an estimate of the accuracy of the quasistatic approximation for avalanche discharge. |
