PHOTOELECTRIC EMISSION AND SURFACE STATES OF SEMICONDUCTING DIAMONDS.
Final scientific rept. for 15 Jan 63-15 May 65.
OKLAHOMA STATE UNIV STILLWATER RESEARCH FOUNDATION
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Photoelectric emission from natural semiconducting diamonds was observed with light of wavelengths above 1050A obtained from a carbon arc operated in nitrogen gas at a low pressure. The photoelectric threshold value for electron emission, believed to originate from the filled surface states near the valence band edge, was found to be approximately 2060A which corresponds to 6.02 eV. The work function of the semiconducting diamonds examined is believed to be 6.020.1 eV. The nature of various types of electrical contacts to semiconducting diamonds was investigated. The best noisefree electrical contacts were obtained using titanium hydride. Surface states in diamond were investigated by analysis of the photovoltage at a metal to diamond contact. The photovoltaic spectral response was examined from 2 microns to 185 millimicrons and correlated with the photoconductivity and optical absorption. The temperature dependence of the photovoltage showed a large increase in sensitivity with decreasing temperature. Author