A heterojunction bipolar transistor with separate carrier injection and confinement

A heterojunction bipolar transistor (HBT) structure in which the wide-gap material serves to confine minority carriers only while the injection of carriers into the base is controlled by a homojunction is discussed. This structure offers several advantages over conventional HBTs, including improved electron injection efficiency without bandgap grading. The thickness of the narrow-gap emitter has to be optimized in order to achieve a good confinement effect. The concept can be applied to other HBTs.<
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