Sc-doped GeTe thin films prepared by radio-frequency magnetron sputtering

Area of Science:

• Materials Science
• Thin Film Deposition
• Semiconductor Physics

Background:

• Germanium telluride (GeTe) is a promising material for phase-change memory applications.
• Doping GeTe with other elements can tune its properties for improved performance.
• Understanding the impact of doping on the amorphous-crystalline phase transition is crucial.

Purpose of the Study:

• To deposit and characterize Sc-doped GeTe thin films using radio frequency magnetron co-sputtering.
• To investigate the effect of scandium (Sc) doping on the structural, electrical, and optical properties of GeTe thin films.
• To evaluate the potential of these materials for phase-change applications.

Main Methods:

• Radio frequency magnetron co-sputtering of GeTe and Sc targets.
• Characterization using SEM-EDX, XRD, AFM, sheet resistance measurements, variable angle spectroscopic ellipsometry, and TOF-MS.
• Analysis of as-deposited (amorphous) and annealed (crystalline) film properties.

Main Results:

• Sc-doped GeTe thin films with varying Sc content (4-14 at%) were successfully deposited.
• Crystallization temperatures ranged from 153-272 °C and increased with Sc content.
• Significant electrical contrast (sheet resistance ratio R_annealed/R_as-deposited from 1.37x10^-4 to 9.1x10^-7) and optical contrast (|Δn|+|Δk| from 1.88-3.75) were observed upon annealing.

Conclusions:

• Scandium doping effectively modifies the crystallization behavior and phase transition properties of GeTe thin films.
• The observed large electrical and optical contrasts highlight the potential of Sc-doped GeTe for advanced memory and optical devices.
• Optimized Sc content (e.g., 8 at%) can maximize the desirable property changes for specific applications.