Effects of oxygen atmosphere on surface properties of ScO/W(100) system as Schottky emitter at high temperature

The dependence of properties of the ScO/W(100) system on the partial pressure of oxygen was investigated by means of Auger electron spectroscopy, low‐energy electron diffraction and work function measurement. The (1 × 1)‐ScO/W(100) surface having a low work function, which was prepared by heating at 1700 K under ultrahigh vacuum (UHV) conditions, hardly showed any changes in surface properties at 1500 K, the operating temperature of the ScO/W(100) emitter, in a UHV of ∼5 × 10 −10 Torr. In contrast, the (1 × 1) ScO/W(100) surface was changed to the (2 × 1)‐(1 × 2) ScO/W(100) surface having a high work function by heating at 1500 K in an oxygen atmosphere of even 5 × 10 −9 Torr. The present results revealed that the partial pressure of oxygen around the ScO/W(100) tip is one of the most important factors for determining the optimum preparation and operating conditions of the ScO/W(100) emitter. Copyright © 2006 John Wiley & Sons, Ltd.