A short-term high-current-density reliability investigation of AlGaAs/GaAs heterojunction bipolar transistors

In high current and power density applications of AlGaAs/GaAs heterojunction bipolar transistors (HBT's), reliability is a critical issue, Therefore, in this letter we show results of a fundamental investigation on the temperature and current dependence of the fast initial rise of the dc-current gain (burn-in), which takes place during stress at current densities beyond those of today's applications. We find that the burn-in occurs at lower device junction temperatures (135 degrees C) than previously reported in literature, and that it depends linearly on the current density. An activation energy of 0.4 eV is extracted for the burn-in effect.