Abstract
The oxide thickness δ of a tunnel MOS diode is varied over the range 10 to 45 Å. This is done in an effort to establish the restrictions upon δ for which thermal equilibrium in the semiconductor is a valid approximation under the application of bias. Particular attention is paid to the reverse-bias case, and most of the experimental results are for δ>25 Å. A transition is observed from the behaviour of the ideal Schottky barrier to that of the thick-film MOS device. The ac conductance and capacitance together with dc current characteristics are studied as continuous functions of bias. From these results, information is obtained which relates the quasi-Fermi levels for (i) majority carriers, (ii) minority carriers and (iii) electrons in the interface states to δ. Thermal equilibrium statistics are found to be applicable to the semiconductor in the presence of a bias voltage when δgreater, similar30 Å, which compares with a theoretical prediction of δgreater, similar13 Å.
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