Modulation doped field effect transistor having built-in drift field
US5436474A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 7, 1994 |
| Grant date | Jul 25, 1995 |
| Priority date | — |
| Expiry date | Dec 7, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/852
Abstract
A MODFET device has highly doped source and drain regions separated by an undoped semiconductor alloy in which the mole fraction is graded between the source and the drain and with a conduction (and/or valence) band discontinuity at the heterojunction between the source and semiconductor alloy channel region of the device. Due to the graded mole fraction, the bandgap of the undoped semiconductor alloy decreases along the channel from the source to the drain and creates a built-in electric field. The higher bandgap in the source compared to that in the channel permits high energy carrier injection into the channel, with the built-in longitudinal electric field increasing carrier drift velocity and reducing transit time between the source and drain. In a preferred embodiment, the MODFET device has a vertical structure with the source and semiconductor alloy layers stacked on a drain substrate. The channel is defined by selectively etching the stacked structure with the exposed edge of the semiconductor alloy layer forming the channel. An undoped semiconductor layer and a modulation doped semiconductor layer are formed over the exposed edge with the undoped layer forming a spacer for …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.