Thermionic and Photoelectric Emission from Magnesium Oxide
| Autor: | Eugene B. Hensley, James R. Stevenson |
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| Rok vydání: | 1961 |
| Předmět: | |
| Zdroj: | Journal of Applied Physics. 32:166-172 |
| ISSN: | 1089-7550 0021-8979 |
| DOI: | 10.1063/1.1735972 |
| Popis: | Measurements of the thermionic emission as a function of temperature and the photoelectric yield as a function of the photon energy in the range from 2.5 ev to 11.5 ev have been made on magnesium oxide in the form of thin films, powders, and single crystals. The thermionic emission measurements indicate that the position of the Fermi energy in most samples of MgO is controlled primarily by the electrons in a donor level located approximately 3.4 ev below the vacuum level. Measurements of the enhancement of the photoelectric yield in the impurity sensitive region gives evidence for impurity levels slightly greater than 2.4 ev and 5 ev below the bottom of the conduction band. A sharp rise in yield at 7.5 ev in active samples coincides with the optical absorption edge associated with exciton formation. Heating the samples in oxygen greatly reduces the rise at 7.5 ev but has little effect on the yield at energies greater than 10 ev. From this it is concluded that the energy difference from the top of the filled band to the vacuum level is less than 10 ev. |
| Databáze: | OpenAIRE |
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