Browse Prior Art Database

MOS Flat Band Voltage Measurement

IP.com Disclosure Number: IPCOM000075740D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Yun, BH: AUTHOR

Abstract

This method allows for the direct determination of flatband voltage (FBV) in MOS devices by optically generating excess carriers in the space charge region of the semiconductor, and monitoring the transient photoresponse of the MOS device as a function of the applied field.

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MOS Flat Band Voltage Measurement

This method allows for the direct determination of flatband voltage (FBV) in MOS devices by optically generating excess carriers in the space charge region of the semiconductor, and monitoring the transient photoresponse of the MOS device as a function of the applied field.

Semiconductor material 1 is optically stimulated by a series of light pulses 2 having a wavelength near the absorption edge of semiconductor 1. Alternately, if the material of contact 4 is optically transparent, it would be more advantageous to use light pulses 2'. At the same time a slowly rising bias, V1, is applied to semiconductor 1. If V1 is different from FBV and is such that an inversion layer exists in the semiconductor at the surface, then the optically generated excess carriers in the space-charge region would result in a transient current flowing through the external circuit giving rise to the amplified voltage V2. As V1 approaches FBV the space charge width decreases, resulting in a corresponding decrease in the number of optically generated carriers in the space charge region. Therefore, the amplitude of V2 decreases as V1 approaches FBV. When V2 goes to zero, V1 equals FBV.

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