Single-Defect Spectroscopy via Random Telegraph Noise in Graphene-Contacted ReS$_2$-hBN Heterostructures

TL;DR

This study demonstrates defect spectroscopy in high-quality ReS2-hBN FETs with graphene contacts, revealing intrinsic defect dynamics through random telegraph noise analysis, and identifies substitutional carbon-related centers as key defects.

Contribution

It introduces a novel device architecture enabling intrinsic defect spectroscopy in ReS2, a low-symmetry 2D semiconductor, using RTN analysis to identify specific defect types.

Findings

RTN observed in micron-scale ReS2 channels at 90-150 K

RTN evolves into 1/f noise with temperature increase

Substitutional carbon-related centers in hBN are identified as dominant defects

Abstract

Defect spectroscopy in two-dimensional (2D) field-effect transistors (FETs) requires device architectures that suppress contact and disorder artifacts while preserving intrinsic carrier dynamics. Here, we demonstrate ReS$_2$-hBN FETs with few-layer graphene (FLG) van der Waals contacts that form nearly barrier-free interfaces, enabling intrinsic transport in ReS$_2$, an anisotropic, low-symmetry TMDC rarely exhibiting disorder-free behavior. The clean ReS$_2$-FLG platform allows direct observation of random telegraph noise (RTN) even in micron-scale channels, manifested as discrete two-level current fluctuations between 90-150 K arising from stochastic trapping at localized hBN defect sites. With increasing temperature, the RTN evolves into a 1/f spectrum as multiple traps activate. Statistical analysis of RTN amplitudes and capture-emission kinetics identifies substitutional carbon-related centers in hBN as dominant defects. These findings establish a generalizable approach for probing dielectric-origin defect dynamics in intrinsically conducting, low-symmetry 2D semiconductors.