Skip to main content Accessibility help
×
Hostname: page-component-77c89778f8-m42fx Total loading time: 0 Render date: 2024-07-20T19:33:11.305Z Has data issue: false hasContentIssue false

9 - HBT basics

Published online by Cambridge University Press:  05 June 2012

David L. Pulfrey
Affiliation:
University of British Columbia, Vancouver
Get access

Summary

The first commercial bipolar junction transistors (BJTs) were made from germanium. Because of the low bandgap of this material (0.67 eV), the intrinsic carrier concentration is high. As ni increases exponentially with temperature (see (4.19)), these Ge BJTs were unstable, unless operating in a temperature-regulated circuit. Silicon, with its larger bandgap, proved to be a better proposition, and the first Si BJTs appeared in the early 1950s. These transistors ushered in the era of solid-state electronics. They were not challenged until MOSFETs started to appear in the 1960s, and to provide a superior transistor for circuits in which a high input impedance was important. With the advent of CMOS in 1963, the age of large-scale integration began, and the MOSFET became the more ubiquitous transistor. However, as we show elsewhere in this book, the bipolar transistor has inherent advantages in high-frequency performance, due to its superior transconductance, and in high-power applications, due to its favourable geometry. BJTs are also more robust than MOSFETs, which is why many readers will have become familiar with them during their electronics laboratory classes.

Perhaps the biggest event in BJT development in the last 20 years has been the advent of heterojunction bipolar transistors (HBTs). In the single heterojunction version of these transistors, dissimilar semiconducting materials are used for the emitter and the base, whereas the base and collector are made from the same semiconductor.

Type
Chapter
Information
Publisher: Cambridge University Press
Print publication year: 2010

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

  • HBT basics
  • David L. Pulfrey, University of British Columbia, Vancouver
  • Book: Understanding Modern Transistors and Diodes
  • Online publication: 05 June 2012
  • Chapter DOI: https://doi.org/10.1017/CBO9780511840685.010
Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

  • HBT basics
  • David L. Pulfrey, University of British Columbia, Vancouver
  • Book: Understanding Modern Transistors and Diodes
  • Online publication: 05 June 2012
  • Chapter DOI: https://doi.org/10.1017/CBO9780511840685.010
Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • HBT basics
  • David L. Pulfrey, University of British Columbia, Vancouver
  • Book: Understanding Modern Transistors and Diodes
  • Online publication: 05 June 2012
  • Chapter DOI: https://doi.org/10.1017/CBO9780511840685.010
Available formats
×