Вы находитесь на старом сайте НГУ. Перейти на новый сайт

ISSN - 10637834, EISSN - 10906460, Physics of the Solid State, 2004, vol. 46, p. 1949-1953

Low-temperature method of cleaning p-GaN(0001) surfaces for photoemitters with effective negative electron affinity

Tereshchenko O. E., Shaǐbler G. É, Yaroshevich A. S., Shevelev S. V., Terekhov A. S., Lundin V. V., Zavarin E. E., Besyul'kin A. I.

The changes in the chemical composition, atomic structure, and electronic properties of the p-GaN(001) surface upon chemical treatment in an HCl-isopropanol solution and vacuum annealing are investigated by x-ray photoelectron spectroscopy, high-resolution electron energy-loss spectroscopy, and low-energy electron diffraction. It is demonstrated that a considerable part of the surface gallium oxide is removed upon chemical treatment of the GaN surface. Subsequent annealing of the surface under vacuum at temperatures of 400-450°C leads to a decrease in the residual carbon and oxygen contamination to 3-5% of the monolayer. The preparation of a clean p-GaN(0001) surface with a (1 × 1) structure identical to that of the bulk unit cells is confirmed by the low-energy electron diffraction data. The cesium adsorption on the clean p-GaN surface results in a decrease in the work function by ∼2.5 eV and the appearance of an effective negative electron affinity on the surface. The quantum efficiency of the GaN photocathode at a wavelength of 250 nm is equal to 26%. © 2004 MAIK "Nauka/Interperiodica".