Silicon germanium heterobipolar transistor for high speed operation

The high frequency dilemma (limited high frequency operation only possible with high base sheet resistivities) of silicon bipolar junction transistors can be overcome by the application of heterostructures. In a first part we give an overview about the SiGe base heterobipolar-transistor (SiGe-HBT) concept and about the devices realized so far. In the second part we report about our SiGe-HBT device work based on Si-MBE grown structures. Experimental results obtained include transit frequencies up to 100 GHz, maximum oscillation frequencies up to 65 GHz, low base sheet resistivities (0.7 k/spl Omega/spl square/ to 3 k/spl Omega/spl square/), encouraging noise properties (<2 dB at 10 GHz) and successful tests in 24 GHz oscillators.<>