Investigation of Base Transport Mechanism in Silicon-Germanium Heterojunction Bipolar Transistor Operating over Wide Temperature Range

A high breakdown voltage silicon-germanium heterojunction bipolar transistor operated over a wide temperature range from 300 K to 10 K has been investigated. The measured Gummel characteristics illustrate that the collector current and base current both shift to the higher voltage as the temperature decreases. The fT/fmax are extracted to be 23/40 GHz at 300K, 28/40 GHz at 90 K, and 25/37GHz at 10K, respectively. The effective amplification range becomes narrow as the temperature decreases. And the ideality factor of base current in the low current region is shown to be temperature-dependent and its value is much larger than 2 at cryogenic temperatures. This phenomenon indicates that the base current is not only contributed by drift, diffusion, and Shockley-Read-Hall recombination, but also by trap-assisted tunneling. The Hurkx local trap-assisted tunneling has been used to analyze the non-ideal base transport mechanism. And a calibrated TCAD device model is developed to further verify this non-ideal transport mechanism.

GaInP/GaAs three-terminal heterojunction bipolar transistor solar cell

We demonstrate a heterojunction bipolar transistor solar cell (HBTSC), a device that exhibits the performance of a double-junction solar cell in a more compact npn (or pnp) semiconductor structure. The HBTSC concept has the advantages of being a three-terminal device, such as low spectral sensitivity and high tolerance to non-optimal band-gap energies, while it has a lower fabrication and operation complexity than other multi-terminal architectures: it can produce independent power extraction from the two junctions without the need for extra isolating or interconnecting layers between them. The two junctions in our proof-of-concept HBTSC prototype, which is made of epitaxial GaInP/GaAs, exhibit independent current-voltage characteristics under AM1.5G illumination, with respective open-circuit voltages of 1.33 and 0.95 V. The HBTSC opens a new perspective in the understanding of multi-junction devices, and it is an excellent candidate for the application of low-cost fabrication techniques, and for the implementation of III-V-on-silicon tandems.

A 56–161 GHz Common-Emitter Amplifier with 16.5 dB Gain Based On InP DHBT Process

This paper presents a broadband amplifier MMIC based on 0.5 µm InP double-heterojunction bipolar transistor (DHBT) technology. The proposed common-emitter amplifier contains five stages, and bias circuits are used in the matching network to obtain stable high gain in a broadband range. The measurement results demonstrate a peak gain of 19.5 dB at 146 GHz and a 3 dB bandwidth of 56–161 GHz (relative bandwidth of 96.8%). The saturation output power achieves 5.9 and 6.5 dBm at 94 and 140 GHz, respectively. The 1 dB compression output power is −4.7 dBm with an input power of −23 dBm at 94 GHz. The proposed amplifier has a compact chip size of 1.2 × 0.7 mm2, including DC and RF pads.