Talk:Heterojunction bipolar transistor
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Kroemer factor
editThe term "Kroemer factor" has been removed because this factor is completely unknown. A search on the web will only return hits that link back to this page. —Preceding unsigned comment added by Eowynne (talk • contribs) 11:40, 31 March 2010 (UTC)
- Reinstated, with ref. Pol098 (talk) 15:51, 26 July 2011 (UTC)
The Kroemer factor is a measure of the injection efficiency of the hetero junction itself. The efficiency of an HBT also include losses in the base. This base transport factor completely limits the gain of a high-speed HBT. Eowynne (talk) 20:23, 12 September 2011 (UTC)
epitaxy
editIn the Fabrication section it says:
"Due to the need to manufacture HBT devices with extremely thin base layers, molecular beam epitaxy is principally employed."
This is true up to a point. Other techniques are used depending on the material system. Notably IBM et al. use a proprietary UHV CVD system for SiGe. Other techniques used include MOVPE for quaternary systems.
I didn't want to change the entry for feat of treading on someone's toes.
Roy