Chemical vapor deposition synthesis of (GeTe)n(Sb2Te3) gradient crystalline films as promising planar heterostructures

TL;DR

This paper presents a rapid chemical vapor deposition method to synthesize gradient crystalline GeSbTe films with controllable composition, enabling tunable properties for memory and optical applications.

Contribution

It introduces a novel CVD process for gradient GST films with compositional control without changing precursors, advancing memory and optical device fabrication.

Findings

Successful synthesis of gradient crystalline GST films.

Compositional variation affects optical and electrical properties.

Potential for multilevel memory and optical modulation applications.

Abstract

Phase-change materials of the (GeTe)n (Sb2Te3) (GST) system are of high relevance in memory storage and energy conversion applications due to their fast-switching speed, high data retention, and tunable properties. Here, we report on a fast and efficient CVD-based method for the fabrication of crystalline GST films with variable Ge/Sb atomic content. In particular, the approach enables compositional control without changing the precursor, facilitating a gradient synthesis of Ge3Sb2Te6, Ge2Sb2Te5, and GeSb2Te4 phases in a single attempt. The analyses of their structural, optical, and electrical aspects highlight how compositional variation influences the film's properties. Our findings demonstrate a straightforward approach enabling the preparation of gradient crystalline GST films with tunable morphology and functionality. These gradient films can potentially provide in-plane multilevel and gradual switching thresholds for memory applications and altered refractive index and absorption for optical modulation and filtering applications.