Electron Beam Radiolysis-Assisted Growth of Rutile TiO2 Thin Films

Abstract A new approach for growing crystalline thin films is developed that takes advantage of electron beam radiolysis as a constructive force to rearrange atoms into a crystalline structure. It is demonstrated that by irradiating the surface of a TiO2 film by an electron beam supplied by a reflection high-energy electron diffraction (RHEED) gun inside the MBE chamber during growth, a crystalline film can be grown at much lower substrate temperatures, where deposited films typically appear amorphous. Here, rutile TiO2 films were grown using hybrid molecular beam epitaxy (MBE), allowing atomic-level control of growth as well as an observation of radiolysis-driven crystallization. Analysis was carried out using a combination of SEM and atomic-resolution STEM imaging. It is also shown that by tuning the temperature of the substrate and the dose of the electron beam, the degree of crystallinity of the film can be controlled.