"Second breakdown" in transistors

Mechanisms leading to erratic snapback behavior in bipolar junction transistors with base emitter shorted

“…In this circuit, the voltage across each of the reverse-biased p / n junctions collapses due to the application of a fast voltage ramp. [2][3][4][5][6][7][8][9][10][11][12][13][14] Typically, shorter delays of a few nanoseconds occur for current-mode second breakdown, 8,[15][16][17][18][19] while larger delays of milliseconds have been attributed to thermal initiation. It has been observed that when the reverse bias across a p / n junction increases sharply near the breakdown region, producing a large displacement current, the device may exhibit either of two different types of breakdown.…”

“…1 Transistorized Marx bank circuits are used for generating high voltage, fast rising pulses for driving pockel cells used for optical pulse switch out in ultrashort-pulse lasers. [4][5][6][7] For both of these triggering mechanisms, second breakdown is believed to be due to the positive feedback nature of the current-controlled negative resistance, causing the constriction of current through narrow conducting regions known as hot filaments. 1 The sudden collapse of voltage across the p / n junctions and bipolar junction transistors, called second breakdown ͑SB͒, is always preceded by an increased current due to an avalanche breakdown and a delay time before the initiation of the breakdown.…”

“…[2][3][4][5][6][7][8][9][10][11][12][13][14] Typically, shorter delays of a few nanoseconds occur for current-mode second breakdown, 8,[15][16][17][18][19] while larger delays of milliseconds have been attributed to thermal initiation. [5][6][7][8] In BJTs with an n + / p / n − / n + structure, high current densities occur during turn-on and turn-off transients when lateral flow of base current produces a voltage drop across the emitter-base junction that leads to the base push-out effect, also known as "current-induced avalanche injection." In thermal-mode breakdown, the negative resistance is due to enhanced carrier generation caused by heating effects from the generated carriers, while in current mode the effect is due to the avalanche injection at the n − / n + junction.…”

Measurement methods for the semiconductor device industry :

“…Initial experimental work demonstrated that all the existing models were inadequate to^explain the effect and showed that second breakdown was a characteristic of all transistors. 13 Pulse measurements of second breakdown revealed the existence of a delay time between the start of the pulse and the initiation of second breakdown as shown in Fig. 6.…”

“…5, and in diodes. 13 It was also found that rather than being unique 4 I m depended on the operating conditions of the transistor. Although a transistor is not necessarily harmed by an excursion into second breakdown, irreversible damage can occur if the current is sufficiently large.…”