Unraveling the Atomic Structure of Bulk Binary Ga–Te Glasses with Surprising Nanotectonic Features for Phase-Change Memory Applications

Abstract

Binary Ge–Te and ternary Ge–Sb–Te systems belong to flagship phase-change materials (PCMs) and are used in nonvolatile memory applications and neuromorphic computing. The working temperatures of these PCMs are limited by low-T glass transition and crystallization phenomena. Promising high-T PCMs may include gallium tellurides; however, the atomic structure and transformation processes for amorphous Ga–Te binaries are simply missing. Using high-energy X-ray diffraction and Raman spectroscopy supported by first-principles simulations, we elucidate the short- and intermediate-range order in bulk glassy Ga x Te1–x , 0.17 ≤ x ≤ 0.25, following their thermal, electric, and optical properties, revealing a semiconductor–metal transition above melting. We also show that a phase change in binary Ga–Te is characterized by a very unusual nanotectonic compression with the high internal transition pressure reaching 4–8 GPa, which appears to be beneficial for PCM applications increasing optical and electrical contrast between the SET and RESET states and decreasing power consumption.

Emerging Two‐Dimensional Tellurene and Tellurides for Broadband Photodetectors

“…As a highly stable tellurium metal in a dry environment at room temperature, GaTe is extensively used in the optoelectronic and semiconductor industries and so on. [106][107][108][109][110][111] The structure of GaTe is diverse, with the material appearing as a monoclinic phase in the bulk state, and it has a hexagonal phase when the layers are reduced to a few or even only one. The monoclinic phase of GaTe appears as a semiconductor with a direct bandgap of 1.7 eV, while the hexagonal phase of GaTe appears as an indirect bandgap, with the VBM shifting toward the Γ point as the number of layers rises rapidly approaching the energy bandstructure of bulk GaTe.…”

Deciphering Fast Ion Transport in Glasses: A Case Study of Sodium and Silver Vitreous Sulfides

“…Several spectra at different locations were taken for each sample to ensure homogeneity and reproducibility of the Raman results. The spectral background subtraction and data analysis were described in detail previously. , …”

“…The spectral background subtraction and data analysis were described in detail previously. 42,43 2.3. Neutron Diffraction Measurements.…”

Unexpected Role of Metal Halides in a Chalcogenide Glass Network

“…The FPMD simulations included sample annealing above the glass transition temperature, 56 ps at 500 K for (AgI) 0.1 (As 2 S 3 ) 0.9 and 32 ps at 450 K for (AgBr) 0.5 (As 2 S 3 ) 0.5 , using a Nosé-Hoover thermostat chain controlling the temperature [36,37] and the final modeling over 50 ps or 38 ps at 300 K for the two systems, respectively. Further FPMD details can be found in Supplementary material, including Figures S3 and S4, and elsewhere [38][39][40].…”

“…First neighbor interatomic distances r and partial coordination numbers Nij in (AgI) 0.1 (As 2 S 3 ) 0.9 and (AgBr) 0.5 (As 2 S 3 ) 0.5 glasses.. chemical disorder in chalcogenide glassy systems seems to be a common feature of FPMD simulations using PBE or PBEsol and requires the use of advanced hybrid functionals, TPSS [76,77], BLYP [78][79][80] or PBE0 [38][39][40], to improve the agreement with experiments. Nevertheless, the simulated partial functions reflect reasonably well the diffraction results.…”