Transient Overshoot Voltages During VF-TLP Pulses for Bipolar Devices in the Presence of Lowly Doped Regions

The transient overshoot behavior of bipolar devices is investigated by means of very fast transmission line pulses (VF-TLP). All devices under investigation, a forward biased diode, an open base transistor and a SCR comprise a lowly doped region (LDR). Measurements have been done for rise times of 0.3ns and 1ns. To separate the voltage drop inside the device from parasitic contributions TCAD simulations have been performed. The analysis shows that for a fixed length of LDR the effect of the lowly doped region depends on the type of the device and is linked to the charge carrier distribution inside the LDR. In addition, the effect of the length of the LDR on transient voltage overshoot is compared for a forward biased diode and an SCR.