Vertical bipolar transistors on buried silicon nitride layers

The letter reports on the integration of vertically operating n-p-n-bipolar transistors with base widths of about 1 µm in silicon-on-insulator (SOI) structures. Nitrogen ion implantation at substrate temperatures of 550°C and subsequent SiCl
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epitaxy provide SOI films with excellent crystalline quality. Conventional bipolar diffusion processes have been applied in order to fabricate diodes and vertical bipolar transistor arrays on thus isolated epitaxial layers. The leakage current of SOI diodes exceeds the value for bulk devices only by a factor of 2. The transistors exhibit emitter current gains of up to 100 and emitter-collector breakdown voltages of up to 35 V.