Electrical and Computer Engineering ETDs

Publication Date



This thesis is the culmination of an investigation into the pulsed field effect technique. Basically, the pulsed field effect technique is a measurement of the surface conductance of a semiconductor under the influence of a transverse electric field. The pulsed field effect has been used to investigate surface states and interface states at the silicon surface. The nature of this technique allows it to be used in analyzing the metal-oxide-semiconductor field effect transistor (MOSFET). Specifically, the investigation has been to determine if the pulsed field effect technique could be used to investigate fast interface states which are located at the silicon/silicon-dioxide interface. These states are close to the valence and conduction band edges. They are able to exchange charge with the bands relatively fast, as compared to those which are closer to the center of the energy band gap.

The purpose for investigating fast interface states in MOSFETs is to see if there is any correlation between the original densities of these states and ionizing radiation effects in the device. Ionizing radiation produces two major effects in MOSFETs which occur at the interface of the device. One effect is a change in the fixed positive oxide charge which exists in the gate insulating material (i.e., silicon­dioxide). The other effect is the change in interface state densities at the silicon/silicon-dioxide interface. Through a pulsed field effect measurement it would be possible to investigate any correlation between original fast interface densities and radiation effects on the MOSFET. If such a correlation exists, then it would be desirable to use the pulsed field effect technique as a screen for MOSFET radiation susceptibility. This technique is being evaluated because it provides a relatively fast and simple measurement which would be applicable in production line environments.

This investigation resulted in the development of a pulsed field effect technique which determines the interaction of fast interface states with the channel conductance of the MOSFET. It scans a portion of the silicon band gap not obtainable using any other simple interface state analysis technique. Currently, the evaluation of this technique as a radiation screening technique is inconclusive. Additional device parameters, which require different measuring techniques, need to be measured. This would allow better correlative analysis which is necessary for a thorough evaluation of this technique.

Document Type




Degree Name

Electrical Engineering

Level of Degree


Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Harold Dean Southward

Second Committee Member

Wayne Willis Grannemann

Third Committee Member

Roy Arthur Colclaser