Electron Diffraction Study of the Structural Changes in a Thin GeTe Crystal Exposed to High-Power Femtosecond Laser Radiation

Abstract

The possibility of amorphization of a thin germanium telluride crystal irradiated by high-power 800-nm femtosecond laser pulses has been investigated. The sample was a 20-nm-thick film of crystalline semiconductor GeTe. An electron diffractometer with a source of short photoelectron pulses was used to study the structural changes. The electron diffraction patterns were analyzed, and the α- and β- phases have been identified in GeTe. It is established that sample ablation occurs in the strong field of femtosecond laser pulses, which is accompanied by a decrease in the crystalline phase thickness to 5–6 nm without any significant amorphization of the sample. A specific feature of the observed process—the absence of light-induced transition of a thin GeTe film from the crystalline to the amorphous state under femtosecond laser irradiation—is noted. Possible causes of the revealed effect are discussed.