Drawbacks of homojunction laser diode
Answers
Heterojunction bipolar transistors (HBTs) are a class of bipolar transistors with the (p–n) junction made up of two dissimilar materials (hence hetero-junction). The behavior of these devices is quite different from conventional bipolar transistors (which are known as homojunction transistors as the junctions are made of similar materials). This article gives a summary of materials and fabrication issues in heterojunction transistors, as well as electrical properties, concentrating on the high-speed and high-performance circuit area where the HBT devices show most advantage.
The main drawback of the HWCVD process is that it is challenging to prevent epitaxial growth of silicon. Epitaxial silicon growth negates the benefits of the intrinsic layer, as it pushes the true heterojunction to the epidoped layer interface. This epitaxial growth can be minimized in HWCVD by keeping the deposition temperature of the emitter intrinsic layer as low as possible (~100°C) [53].