Substituting the base of a Silicon bipolar junction transistor with a thin, strained Silicon-Germanium layer potentially improves the dynamic device performance significantly, because the Silicon-Germanium film has a lower band gap then Silicon has. In this project we develop the technology for growth of the strained Silicon-Germanium layers on silicon, and the post growth processing needed for fabrication of Silicon-Germanium Hetero Junction Bipolar Transistors (HBT's). This is a rather difficult task, as very strict control of the vertical dimensions of the device is needed in order to realise the potential advantages of the technology. The devices we fabricate has a grown Boron doped Silicon-Germanium base thickness of only 20nm, and the post growth process must not cause the Boron profile in the base to widen more than 1nm, hence, the thermal budget for the process har to be very low. We have successfully fabricated HBT's with good static and dynamic properties.
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