Measurement of substrate current in SOI MOSFET's
Abstract
A new 'quasi-SOI' MOSFET structure is shown to allow direct measurement of substrate current in a fully-depleted SOI device. The holes generated by impact ionization near the drain are collected at the substrate terminal after they have traversed the source-body barrier and caused bipolar multiplication. By monitoring this hole current, direct characterization of the impact-ionization multiplication factor, M, and the parasitic bipolar gain, beta, was performed. It was found that M - 1 increases exponentially with V (sub DS) and decreases with V (sub GS), exhibiting a drain field dependence. The bipolar gain beta was found to be as high as 1000 for V (sub GS) - V (sub T) = 0 V and V (sub DS) = - 2.5 V, but decreases exponentially as V (sub DS) increases. Finally, it was found that beta also decreases as V (sub GS) increases.
- Publication:
-
IEEE Electron Device Letters
- Pub Date:
- April 1994
- DOI:
- 10.1109/55.285406
- Bibcode:
- 1994IEDL...15..132N
- Keywords:
-
- Bipolarity;
- Direct Current;
- Electrical Measurement;
- Field Effect Transistors;
- Metal Oxide Semiconductors;
- Semiconductor Devices;
- Soi (Semiconductors);
- Substrates;
- Drainage;
- Ionization;
- Electronics and Electrical Engineering