High gain,broadband p-WSe_(2)/n-Ge van der Waals heterojunction phototransistor with a Schottky barrier collector

Mixed-dimensional van der Waals(vdW)heterostructures based on two-dimensional transition metal dichalcogenides and threedimensional semiconductors have led to a new era in next-generation optoelectronics due to the high-quality interfaces and energy band complementation,especially in broadband photodetectors which can be used for all-weather navigation,object identification,etc.However,the reported photodetectors conventionally operated in photodiode mode with low responsivity and a narrow response spectrum.In this study,we report a p-WSe_(2)/n-Ge vdW heterojunction phototransistor with a Schottky barrier collector on n-Ge for broadband photodetection.Large hole/electron injection ratio from p-WSe_(2)/n-Ge heterojunction under forward bias due to their large bandgap offset renders the high photocurrent gain,while the Ge Schottky barrier limits the dark current.The responsivities of the phototransistor at 1.0 V emitter-collector bias are 55,95,and 120 A·W−1 at 405,1,310,and 1,550 nm,respectively,which is superior to that of the corresponding p-WSe_(2)/n-Ge photodiodes.The phototransistor shows a high photocurrent gain of 80,a specific detectivity of 1011 Jones,as well as a fast response time of 290μs at 1,550 nm.The results suggest that the novel phototransistor being implemented with complementary metal-oxide-semiconductor processing is an ideal strategy for high-performance broadband photodetection.

Pomegranate micro/nano hierarchical plasma structure for superior microwave absorption

Inspired by the pomegranate natural artful structure,pomegranate micro/nano hierarchical plasma configuration of Fe/Fe3C@graphitized carbon(FFC/pCL)was constructed based on the green sol-gel method and in-situ chemical vapor deposition(CVD)synthesis protocol.Pomegranate-like FFC/pCL successfully overcame the agglomeration phenomenon of magnetic nanoparticles with each seed of the pomegranate consisting of Fe/Fe_(3)C as cores and graphitized carbon layers as shells.The high-density arrangement of magnetic nanoparticles and the design of pomegranate-like heterostructures lead to enhanced plasmon resonance.Thus,the pomegranate-like FFC/pCL achieved a great electromagnetic wave(EMW)absorbing performance of 6.12 GHz wide band absorption at a low mass adding of only 16.7 wt.%.Such excellent EMW performance can be attributed to its unique pomegranate hierarchical plasma configuration with separated nanoscale iron cores,surface porous texture,and good carbon conductive network.This investigation provides a new paradigm for the development of magnetic/carbon based EMW absorbing materials by taking advantage of pomegranate hierarchical plasma configuration.