Multilevel reversible laser-induced phase transitions in GeTe thin films

Abstract

This paper presents the results of a study on the structural properties and dynamics of conductivity of thin (d ∼ 100 nm) films of germanium telluride depending on the phase states reversibly switched by nanosecond pulsed laser radiation with a «top hat» beam profile. It was determined that the threshold of laser radiation energy density at which the phase transition in GeTe thin films from the amorphous to crystalline state is in the range of E = 7.5 ÷ 47.6 mJ/cm2, and the threshold for the reverse transition from the crystalline to amorphous state starts from 47.6 mJ/cm2 and is observed up to 90 mJ/cm2 with no visible damage caused by the ablation. The full time of conductivity change associated with the phase transition between the amorphous and crystalline phases is τCA = 20.2 ns, while for the reverse crystalline to amorphous transition, the conductivity full change time it makes τAC = 52 ns.

Atypical phase-change alloy Ga2Te3: atomic structure, incipient nanotectonic nuclei, and multilevel writing

“…Further details of the pump-probe setup and time-resolved measurements were published previously. [19][20][21] A limited number of experiments were conducted using a femtosecond laser Astrella Coherent (𝜆 pump = 800 nm, the energy density 20 mJ cm -2 ) and a 15 mW probing laser (𝜆 probe = 1550 nm).…”

Electron beam lithography of GeTe through polymorphic phase transformation

“…In fact, it has been previously reported modulating Ge vacancies in α-GeTe via nanosecond pulsed laser radiation to alter the multilevel reversible electrical conductivity of GeTe thin films. 28,29 Other notable reports are about tunning the disorder degree of Ge vacancies in Ge2Sb2Te5 via electron beam irradiation, 30,31,32 which leads to unique optical, electrical, and thermal properties. 33 In our experiment, we vary the time of electron beam irradiation on the region of interest (ROI) and take corresponding atomic-resolution HAADF-and ABF-STEM images in the [11 ̅ 0]pc zone axis.…”

Structural Evolution of Millisecond Laser-Induced Metastable Crystalline GeTe

“…We venture to achieve structural phase control in GeTe by using millisecond laser annealing. Efforts to control the phase of GeTe have focused nanosecond-order pulsed switching between the amorphous and crystalline states of thin films of thickness 100 nm or less. − In contrast, herein we use a CW laser, which ensures complete melting of GeTe films thicker than 100 nm.…”