Low-noise implanted-base microwave transistors

An improved small-signal bipolar microwave transistor utilizing ion-implantation has been developed. The structure comprises oxide isolation, arsenic-doped emitters and an ion-implanted base region. A noise figure of 3·9 dB at 8 GHz has been achieved. The variation of the device parameters with the implanted dose has been investigated and the results are interpreted in terms of a simplified model. Implanted emitters and diffused emitters have been evaluated and found to give similar results.