Electron diffraction study of structural changes in a thin GeTe crystal under the action of high-power femtosecond laser radiation

Abstract: We study the possibility of a transition of a thin crystal of germanium telluride into an amorphous form as a result of the action of high-power femtosecond laser pulses at a wavelength of 800 nm. A 20-nm-thick GeTe (GT) crystalline semiconductor film is used as a sample. Structural changes are analysed using an electron diffractometer with a source of short photoelectron pulses. The diffraction patterns are analysed and the α- and β-phases in GeTe are identified. It is found that in a strong femtosecond laser field, there occurs a sample ablation process, which is accompanied by a decrease in the thickness of the crystalline phase to 5–6 nm without significant sample amorphisation. A feature of the observed process is the absence of a light-induced transition from the crystalline to the amorphous state when a thin GT film is irradiated with femtosecond laser pulses. Possible reasons for the observed effect are discussed.

Keywords: femtosecond laser radiation, phase-changing materials, electron diffraction, thin GeTe crystal.