Self-driven photodetectors that can detect light without any external voltage bias are important for low-power applications, including future internet of things, wearable electronics, and flexible electronics. While two-dimensional (2D) materials exhibit good optoelectronic properties, the extraordinary properties have not been fully exploited to realize high-performance self-driven photodetectors. In this paper, a metal–semiconductor–metal (MSM) photodetector with graphene and Au as the two contacts have been proposed to realize the self-driven photodetector. Van der Waals contacts are formed by dry-transfer methods, which is important in constructing the asymmetrical MSM photodetector to avoid the Fermi-level pinning effect. By choosing graphene and Au as the two contact electrodes, a pronounced photovoltaic effect is obtained. Without any external bias, the self-driven photodetector exhibits a high responsivity of 7.55 A W⁻¹ and an ultrahigh photocurrent-to-dark current ratio of ~10⁸. The photodetector also shows gate-tunable characteristics due to the field-induced Fermi-level shift in the constituent 2D materials. What is more, the high linearity of the photodetector over almost 60 dB suggests the easy integration with processing circuits for practical applications.

Both carbon nanotube (CNT) and graphene exhibit excellent properties and have many potential applications in integrated circuits, composite materials, thermal management, sensors, energy storage, and flexible electronics. However, their superior properties are confined to one or two dimensions, thus limiting their utility in interconnects or thermal interface materials that require a 3D structure for efficient electron and/or phonon transport. It is conceivable that a combined CNT-graphene structure would provide new opportunities for realizable applications in these and other fields. In recent years, numerous results on synthesis, structural analyses, theoretical modeling, and potential applications of various CNT-graphene heterostructures have been reported. In this review, we summarize the possible structures that can be formed by connecting CNT and graphene. We then report existing experimental efforts to synthesize the heterostructures based on growth method, catalyst design, and the resulting properties. Also, theoretical studies on various heterostructures are reviewed, with the focus on electron and thermal transport within the heterostructure and across the CNT-graphene interface. Several potential applications are briefly discussed, and a combined theoretical and experimental approach is proposed with the objective of enhancing the understanding of the CNT-graphene heterostructure and attaining a realistic assessment of its feasibility in practical applications.

By elaborating the concept of symmetry breaking in 2D material based photodetectors, we give a concise and generalized framework which covers existing photodetectors with self-driven properties.

Dual probe is capable of simultaneously measuring electric and magnetic fields in the same position, given that perfectly symmetric design is realized on the transmission paths connecting the detection loop and the probe outputs. For general application, a calibration method for the asymmetric probing in near-field measurement with the dual probe is presented, in order to deal with the failure of the traditional calibration due to the asymmetric transmissions in both paths. The asymmetric probing measurement is modeled, and then the proposed calibration to eliminate the asymmetry is further derived based on two independent measurements at two directions (0° and 90°) between the probe and the microstrip line providing a known electromagnetic field at the surface. The calibration method is demonstrated with two kinds of dual probes of different coupling structure. The proposed calibration is validated by introducing the asymmetry to the probing process in the measurement of the standing wave along a conductor-backed coplanar waveguide transmission line.

Two-dimensional (2D) material (graphene, MoS₂, WSe₂, MXene, etc)/group-III nitride (GaN, AlN, and their compounds) hetero-structures have been given special attention, on account of their prospective applications in remarkable performance broadband photodetectors, light-emitting diodes, solar cells, memristors, hydrogen sensors, etc. The utilization of advantages of the above two kind materials provides a solution to the dilemma of the degradation of device performance and reliability caused by carrier mobility, contact resistance, lattice mismatch, interface, and other factors. Therefore, the summary of the recent progress of 2D material/group-III nitride hetero-structures is urgent. In this work, it elaborates on interface interaction and stimulation, growth mechanism and device physic of 2D material/group-III nitride hetero-structures. Initially, it investigates the properties of the hetero-structures, combining the theoretical calculations on interface interaction of the heterojunction with experimental study, particularly emphasizing on interface effects on the performance of hetero-materials. The structure modification (band alignments, band edge position, synergetic work function and so on) at interface contributes to the outstanding properties of these hetero-structures. Subsequently, the growth of 2D material/group-III nitride hetero-structures is introduced in detail. The problems solved by the advancing synthesis strategies and the corresponding formation mechanisms are discussed in particular. Afterwards, based on the 2D material/group-III nitride hetero-structures, extending from optoelectronics, electronics, to photocatalyst and sensors, etc, are reviewed. Finally, the prospect of 2D material/group-III nitride hetero-structures is speculated to pave the way for further promotion.