University of Illinois Urbana-Champaign

Current Blocking in Type-I DHBTs

Bambery, Rohan

This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.

Permalink

https://hdl.handle.net/2142/47071

Description

Title
Current Blocking in Type-I DHBTs
Author(s)
Bambery, Rohan
Contributor(s)
Feng, Milton
Issue Date
2008-05
Keyword(s)
  • current blocking
  • transistors
  • bipolar transistors
  • double-heterojunction bipolar transistors
  • type I double-heterojunction bipolar transistors
  • Kirk effect
Abstract
The phenomenon of current blocking sets the I-V characteristic of heterojunction bipolar transistors apart from their homojunction counterparts. The effect stems from the triangular quantum well energy spike at the base collector junction of the DHBT. The theory governing the effect is discussed using energy band diagrams and potential barriers at the junctions under different DC bias conditions. Current blocking is predicted to be dominant under low bias. This effect decreases at higher bias since the spike is pulled down at the C-B junction. Three Type - I InP/InGaAs/InP DHBTs of different sizes were tested using a 20-μA base current stepping and maximum DC bias VC = 1V. Each of the devices exhibited the classic bowing in the I-V curve which is characteristic of current blocking. These measurements are discussed along with a comparison of the effects of device size on the phenomenon. The results clearly show current blocking under low DC bias and a relative decrease in the effect at a higher VC. The use of Type –II DHBTs effectively overcomes the problem of tunneling through the conduction band spike, and exhibits very little current blocking. The dominant effect in Type –II devices is base push-out or the Kirk Effect. This is discussed in brief along with measurements showing the improvement in the I-V characteristic.
Type of Resource
text
Language
en
Permalink
http://hdl.handle.net/2142/47071

Owning Collections

Senior Theses - Electrical and Computer Engineering PRIMARY
The best of ECE undergraduate research