A Phase Change Material for Reconfigurable Circuit Applications

Dushyant Tomer,Ronald Coutu

doi:10.3390/app8010130

Abstract

The large resistance contrast between amorphous and crystalline states of phase change materials (PCM) makes them a promising candidate for data-storage applications. Germanium telluride (GeTe), an early member of the PCM family, shows ~6 orders of magnitude difference in resistivity upon phase transition. In this paper, two different heating methods, direct (Joule) and indirect thermal heating, were applied to induce a phase transition in vertical and horizontal GeTe resistors. In the electrical measurements, it was observed that thermal heating produces a two orders of magnitude larger difference in GeTe resistivity that the Joule heating, irrespective of the resistor’s geometry and orientation. It was also found that the large inter-electrode distances in horizontal resistors make them impractical for low voltage applications. In addition, a correlation in between crystallization voltage and resistor’s geometrical parameters (i.e., inter-electrode distance and cross-sectional area) was also established. Here, it was found that the threshold voltage increases with resistor length, while it remains unaffected with a change in cross-sectional area. This work provides design guidelines to make use of not only GeTe but also other phase change materials in reconfigurable circuit applications.

Highlights

Temperature-induced amorphous and crystalline states of a phase change material (PCM) possess two distinct energy band structures; they have different physical and chemical properties [1].One such property is reflectivity, which has been utilized in the optical storage industry for storing data in the form of CDs and DVDs [2]
Thermal-induced reversible phase transition has been demonstrated in several chalcogenide compounds such as germanium antimony telluride (GeSbTe or GST), and germanium telluride (GeTe) [4,5,6]
We demonstrated the utility of phase change resistors for reconfigurable circuits

Summary

Introduction

Temperature-induced amorphous and crystalline states of a phase change material (PCM) possess two distinct energy band structures; they have different physical and chemical properties [1].One such property is reflectivity, which has been utilized in the optical storage industry for storing data in the form of CDs and DVDs [2]. Temperature-induced amorphous and crystalline states of a phase change material (PCM) possess two distinct energy band structures; they have different physical and chemical properties [1]. Redaelli et al demonstrate Joule heating induced phase transition in GST electronic memory cells of size ~0.80 μm × 0.40 μm × 60 nm and concluded that the threshold switching in such devices does not depend on structural changes [7]. It was an outcome of competition between trap-assisted carrier recombination and field-assisted carrier generation. In comparison to GST, GeTe has several advantages including higher stability in amorphous

Methods

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Discussion

Conclusion