Electron standing wave at a surface during reflection high energy electron diffraction and adatom height determination

We measure the glancing angle (g) dependence of In L emission from Si(111)- (3×3)-In structure during reflection high energy electron diffraction. The g dependence clearly showed some anomalous intensities under Bragg conditions. These intensities were well explained as a change of the density of electron standing waves on the surface adatoms. Using this phenomenon, a new method for adatom-height determination was developed, and the obtained In adatom height from the first Si layer was 1.83 in the T4 structure.