A novel electrical method to accurately measure the thermal resistance of heterojunction bipolar transistors (HBT's) is presented. The keg advantage of the method is its simplicity, because it requires only the measurement of the device DC output characteristics at two different temperatures. In this brief, the measurement technique is illustrated, applied to multifinger HBT's and compared with other methods

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

The dependence of the collector-emitter offset voltage (V-ceoff) of AlGaAs/GaAs heterojunction bipolar transistors (HBT's) on the base current, substrate temperature, and device geometry has been investigated. We found that V-ceoff decreases at moderate base current (I-b) and begins to increase at very high I-b. Moreover, V-ceoff increases linearly with the temperature and logarithmically with the ratio of the base-collector junction perimeter to the base-emitter junction area, rather than with the ratio of the base-collector to the base-emitter junction areas, as previously reported, Further,more, the measured data do not agree with the classical expression of V-ceoff derived from the Ebers-Moll equations of bipolar junction transistor (BJT). Therefore, from the literature, an alternative expression is used, which provides more insight into the physics of HBT and is demonstrated to agree very well with the experimental data

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