Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




Professor J. Shewchun


The major purpose of the work presented in this thesis has been to consider some important electrical transport properties of Metal-Insulator-Semiconductor (MIS or MOS) and Semiconductor-Insulator-Semiconductor (SIS) diodes.

In particular the d.c. tunnel current-voltage characteristics of the MIS diode are studied and shown to divided naturally into two categories corresponding to the state of equilibrium of the semiconductor of a diode. In "equilibrium" diodes the carrier distributions in the semi-conductor are effectively maintained in thermal equilibrium despite the presence of d.c. current flow. I-V characteristics of a range of this type of diode are presented and analyzed. Tunnel induced non-equilibrium conditions in the semiconductor are also investigated and shown to have visible effects on the I-V characteristics of the MIS tunnel diode. These effects are seen to be functions of oxide thickness, minority carrier supply rate and doping density.

The tunnel currents of both "equilibrium" and "non-equilibrium" diodes are analyzed by comparison with a comprehensive finite temperature tunnel theory. Employment of numerical techniques permits the inclusion in these calculations of the effects of a two band model of the insulator, image force potentials in the barrier and space charge tunneling.

A practical application of the properties of the "non-equilibrium" diode in the form of a new type of active device, the Surface Oxide Transistor (SOT), is demonstrated. The characteristics of such structures are investigated and models of their operation proposed.

The final work presented in this thesis deals with a new type of barrier dominated semiconductor structure, the SIS diode. The capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics of thick oxide diodes of this type are presented and compared with theory. A wide range of interesting characteristics are observed. The d.c. current-voltage behaviour of the SIS tunnel diode, while not studied experimentally, is compared qualitatively with that of the MIS tunnel diode.

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