Clean smooth symmetrical field emission patterns of CdS single crystals of about 2.6 x x lo8 Clem bulk resistivity are obtained by a cleaning procedure based upon hydrogenpromoted field evaporation a t room temperature. The "best image voltage" a t 77 O K is easily reproducible to 3% and by heating a t about 1120 OK, faceting occurs. The value 4.97 eV of the electron affinity is calculated from the Fowler-Nordheim (F-N) equation modified for the case of a degenerate surface with field penetration. The F-N plot shows a hysteresis a t fields higher than 4 x lo7 Vcm-l; this could be explained among other interpretations by an adsorption starting a t high fields. Under conditions of severe contamination, the work function increases to 1.59 eV. L'hmission de champ de monocristaux de CdS ayant une resistivite de volume voisine de 2,6 x lo8 Qcm donne des images propres, symetriques apr&s un nettoyage base sur 1'6vaporation de champ dans l'hydroghe b temperature ordinaire. Le "voltage de meilleure image" B 77 O K est facilement reproductible b 3% et suite b un chauffage aux environs de 1120 OK, certaines facettes grandissent. La valeur 4,97 eV de l'affinite Blectronique est calculee b partir de 1'6quation de Fowler-Nordheim (F-N) modifiee dans le cas d'une surface dBg6neree avec penetration de champ. Les courbes F-N montrent une hysteresis pour des champs supBrieurs b 4 x lo7 Vcm-l; ce qui pourrait s'expliquer parmi d'autres possibilites d'interprktation par une adsorption dBmarrant b champ Bled. Dans les conditions d'extr6me contamination, l'augmentation du travail d'extraction s'8lbve b 1,59 eV.
Fields in the range of 107 Vcm−1 at 77 °K, are shown to cause a deformation of the ZnO (0001) emitter tip, accompanied by surface states formation. This shows up in the Fowler‐Nordheim plot as an irreversible plateau‐like behaviour of the emission current, while the affinity increases. The average density of these surface states is calculated and found to be 1014 cm−2 eV−1.
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