Abstract
The 0.18μm SiGe HBTs operated under high collector bias are analyzed and modeled in this thesis. A new mechanism is found that SiGe HBTs operate at high collector voltage will have two current jumps. These two sudden current jumps occur is due to tunneling effect of electrons in two quantum levels which are formed by conduction band discontinuity at collector-base junction. By multiplying those tunneling electrons with avalanche multiplication factor in the depletion region, large amount of electron-hole pairs will flow out of collector and base terminals. Two stages of current jumps in IC and IB take place correspond to tunnel effect of two quantum levels. Two current jumps at high collector voltage split IC and IB into four regions, respectively. A device model is built by adding on a general HBT equivalent circuit with four switch controlled paths between both collector-emitter and base-emitter junction. Therefore, the model in this thesis can fit the measured results with widely operating range quite accurately. Some useful applications can be simulated by this developed model, such as small signal characteristics, ac characteristics, and circuit design. There may still have many valuable applications for this new mechanism.