RESUMEN
Graphene/silicon Schottky junctions have been proven efficient for photodetection, but the existing high dark current seriously restricts applications such as weak signal detection. In this paper, a thin layer of gadolinium iron garnet (Gd3Fe5O12, GdIG) film is introduced to engineer the interface of a graphene/silicon Schottky photodetector. The novel structure shows a significant decrease in dark current by 54 times at a -2 V bias. It also exhibits high performance in a self-powered mode in terms of an Ilight/Idark ratio up to 8.2 × 106 and a specific detectivity of 1.35 × 1013 Jones at 633 nm, showing appealing potential for weak-light detection. Practical suitability characterizations reveal a broadband absorption covering ultraviolet to near-infrared light and a large linear response with a wide range of light intensities. The device holds an operation speed of 0.15 ms, a stable response for 500 continuous working cycles, and long-term environmental stability after several months. Theoretical analysis shows that the interlayer increases the barrier height and passivates the contact surface so that the dark current is suppressed. This work demonstrates the good capacity of GdIG thin films as interlayer materials and provides a new solution for high-performance photodetectors.
RESUMEN
Carbon nanotube (CNT) probes are used in atomic force microscopes (AFMs) for high-resolution imaging, especially in the measurement of high aspect ratio micro/nano structures. Due to the use of a longer CNT tip leading to the degradation of image resolution, researchers have used several methods to cut CNTs. However, the principle of the selection of the cutting length has hardly been reported. Moreover, the influence of the effect of size on the mechanical properties of a CNT tip is not fully understood. In this study, an accurate model of finite element simulations is constructed on the basis of scanning electron microscopy data to investigate the mechanical properties of a CNT probe. An elastic model is employed to study the factors that influence the critical buckling force at the CNT tip during the measurement process. The calculation shows that the mechanical stiffness of the probe is affected by the diameter and the length-to-diameter ratio of the CNT tip. The changes in the von Mises stress at the bond between the AFM probe and the CNT tip as well as the variation of the strain energy at the CNT tip are discussed. It is hoped that this study will provide guidance for the selection of the cutting length of CNT-AFM probes and propose a basis for probe selection and design in practical measurements.