Aiming at the problem of investigating the degradation and failure mechanism of Darlington transistors under external stresses, the paper carries out research on the modeling and simulation of Darlington transistor. By comparing the electrical parameters of the simulation model with those in the Darlington transistor datasheet, the electrical parameter curves match well, which verifies the effectiveness of the simulation model. By constructing different working environments of electrical and thermal stress, the degradation mechanism of the electrical performance parameters of Darlington transistor is analyzed. The results demonstrate that the internal carrier mobility of the transistor decreases while the intrinsic carrier concentration increases under thermal stress. Accordingly, the current gain of the transistor increases with the rise of temperature, whereas the switching efficiency attenuates with increasing temperature under the condition of heavy load current. Under the electrical stress, the emitter current crowding effect of the M2 transistor in the transistor is significantly enhanced. When the collector peak voltage exceeds 33 V, abrupt changes occur in the behavior of internal carriers of the transistor, leading to a rapid rise in the internal junction temperature and eventually causing the transistor to fail and burn out. The research on the degradation and failure mechanism of Darlington transistor under combined electrical and thermal stresses can provide a theoretical basis for the safety protection of Darlington transistor in practical applications, which is of great significance for engineering practices.
Li et al. (Thu,) studied this question.