RHEED-ISS study on the surface at high temperature

Surface characterization of zirconia-coated tungsten Schottky emitters by using RHEED, AES, and TOF-SIMS

“…This phase transition was reversibly observed depending on the temperature, and transition from p(1×1) to c(4×2) + c(2×4) was also observed in the cooling process. These structural changes on the tip surface are in excellent agreement with the previously reported results from the planer-sample [12,[13][14][15][16][17][18][19][20][21][22][23][24][25][26]. This confirms that the planer-sample can be used as the simulating sample of the emitter tip.…”

“…In the 1990s, Shimizu et al [11][12][13] and Satoh et al [14,15] precisely analyzed surface periodicity of the Zr/O/W(001) surface by using reflective high-energy electron diffraction (RHEED) and low energy electron diffraction (LEED). In their experiments, they used a single-crystalplanar-sample as a well-defined sample simulating a Schottky emitter tip.…”

“…In their experiments, they used a single-crystalplanar-sample as a well-defined sample simulating a Schottky emitter tip. They found that the surface periodicity was changed from a c(4×2) + c(2×4) double domain superstructure to p(1×1) between 1000 K and 1400 K [12][13][14]15], and that the reduced work function of the surface was accompanied by a change in the periodicity [12,13]. It has been expected that the surfaces on the emitter tip will be directly measured and that a well-defined sample will be verified as the simulation of the emitter tip; the structural model of the emitter surface will be proposed through analyses of not only the periodicity but also the bonding states of Zr, O, and W; and the mechanism of (001) selectivity will be revealed through comparing the other surfaces on the emitter, such as (110) and (112) [16][17][18][19].…”

Surface structure analysis of Zr‐O/W(100) at high temperature by x‐ray photoelectron diffraction

“…Lee et al have studied the surface structure of Zr-O/W(100) with AES and ion scattering spectroscopy (ISS). 2,3 These results revealed that Zr atoms existed on the W(100) surface and the surface structure of Zr-O/W (100) was reversibly changed from c 2 ð 4 C c 4 ð 2 (low temperature) to p(1 ð 1) (high temperature) at 1000 K. In addition, investigations into the c 2 ð 4 C c 4 ð 2 double-domain structure of Zr-O/W(100) were reported by Satoh et al. 4,5 However, the mechanism of a decrease in the work function has never been fully understood.…”