An integrated and multi-purpose microscope for the characterization of atomically thin optoelectronic devices

Abstract

Optoelectronic devices based on graphene and other two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs), are the focus of wide research interest. They can be the key to improving bandwidths in telecommunications, capacity in data storage, and new features in consumer electronics, safety devices, and medical equipment. The characterization of these emerging atomically thin materials and devices strongly relies on a set of measurements involving both optical and electronic instrumentation ranging from scanning photocurrent mapping to Raman and photoluminescence (PL) spectroscopy. Furthermore, proof-of-concept devices are usually fabricated from micro-meter size flakes, requiring microscopy techniques to characterize them. Current state-of-the-art commercial instruments offer the ability to characterize individual properties of these materials with no option for the in situ characterization of a wide enough range of complementary optical and electrical properties. Presently, the requirement to switch atomically thin materials from one system to another often radically affects the properties of these uniquely sensitive materials through atmospheric contamination. Here, we present an integrated, multi-purpose instrument dedicated to the optical and electrical characterization of devices based on 2D materials which is able to perform low frequency electrical measurements, scanning photocurrent mapping, and Raman, absorption, and PL spectroscopy in one single setup with full control over the polarization and wavelength of light. We characterize this apparatus by performing multiple measurements on graphene, transition metal dichalcogenides (TMDs), and Si. The performance and resolution of each individual measurement technique is found to be equivalent to that of commercially available instruments. Contrary to nowadays’ commercial systems, a significant advantage of the developed instrument is that for the first time the integration of a wide range of complementary optoelectronic and spectroscopy characterization techniques is demonstrated in a single compact unit. Our design offers a versatile solution to face the challenges imposed by the advent of atomically thin materials in optoelectronic devices.