Electron beam stimulated nonthermal crystallization of CdS surface layers: Observations by real-time atomic-resolution electron microscopy

The transformations of partially amorphous CdS surfaces induced by 100-400 keV electrons have been followed in real time by atomic-resolution electron microscopy. A definite sequence of atomic rearrangements leading to nucleation and growth of CdS and Cd crystals was observed. These processes are believed to be due to nonthermal mechanisms involving inelastic electron collisions rather than direct knock-on collisions between electrons and the atomic nuclei since there is no threshold over the range of incident electron energies. These effects may be responsible for the degradation of electron beam pumped CdS lasers which has been reported elsewhere.