Phase-Change Materials, 1/f Noise, and Phase Synchrony

Abstract

In this article, we study $1/f^{\gamma },\gamma \approx 1$ electrical noise in amorphous phase-change materials. Given the relevance of noise in recent applications, it is necessary to gain a deeper perspective on its nature in phase-change semiconductors, a promising class of materials. Electron conduction is envisaged in terms of an envelope function and a field-dependent Bloch wave function; the electron transport across the structure is modeled as driven phase oscillators under a weak field and obeys a Kuramoto-type equation. Its solutions naturally divide into a phase-synchronized group and phase-desynchronized oscillators. The former is comprised by long-lived pairs or aggregates and are responsible for $1/f,\gamma =1$ noise. We identify the dividing frequency between $\gamma =1$ noise and $\gamma \ne 1$ noise. The phase-desynchronized carriers generate $\gamma \ne 1$ noise and are single carriers, not aggregates, and are short-lived. We apply our analysis to recent experiments.