Browse Prior Art Database

Measurement of IGFET Impact Ionization Current

IP.com Disclosure Number: IPCOM000084784D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

El-Kareh, B: AUTHOR [+2]

Abstract

This measurement technique allows the determination of impact ionization currents on insulated gate field-effect transistor (IGFET) structures down to the femtoampere range. The technique requires an IGFET T and a diode D tied to the plate P of a metal insulated semiconductor (MIS) capacitor (or equivalent). IGFET T is the device under test and D,P the monitoring device.

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Measurement of IGFET Impact Ionization Current

This measurement technique allows the determination of impact ionization currents on insulated gate field-effect transistor (IGFET) structures down to the femtoampere range. The technique requires an IGFET T and a diode D tied to the plate P of a metal insulated semiconductor (MIS) capacitor (or equivalent). IGFET T is the device under test and D,P the monitoring device.

The plate P is precharged to a known voltage +V in the case of a N-channel FET, through a high-impedance, low-capacitance switch 10. IGFET T is operated under conditions to generate impact ionization current. The holes flow toward substrate 12 at a bias potential -Vss. Electrons flow predominantly to the drain of
T.

A fraction of electrons injected from substrate 12 will be collected by diode D, which will reduce the reverse bias on the diode and lower the precharged gate voltage. The current i can be measured by comparing the decay of the voltage on P with a curve obtained when T is not providing impact ionization current. This technique may be used to study impact ionization mechanisms in IGFET's at current levels not possible with available instruments.

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