Broadband Photodetectors Based On Low-dimensional Materials

Broadband light photodetection can be extensively applied in many applications,like communication,imaging,national defense and aerospace,absorbing many researchers' endless efforts.With new low-dimensional nanomaterials emerging,they exhibit outstanding properties including broadband absorption,strong light-matter interactions,excellent flexibility,ultra-thin thickness,and compatibility with varieties of substrates.And so on,has injected new vitality into the field of wide-band light detection.One of the main purpose of this paper is to achieve a highly effective photodetection of broadband light by forming a hybrid structure between plasmonic nanocrystals Cu3-x P and graphene.Also,we synthesized heterostructrue based on small bandgap materials(Pt S2,Pt Se2)by chemical vapor deposition(CVD)method and then demonstrated an efficient and self-driven heterostructrue photodetector.My project is focused on the following aspects of low-dimensional nanomaterials.1.Broadband graphene photodetectors enhanced by Cu3-xP colloidal nanocrystalsWe systematically showed a graphene-Cu3-x P heterojunction photodetector and studied photodetector performance with the different self-doping concentration of Cu3-x P and the different surface ligands.We found that Cu3-x P nanocrystals can change the doped state of pristine graphene film.On the other hand,the localized surface plasmon resonance(LSPR)in Cu3-x P will enhance the absorption of hybrid photodetector in near-infrared wavelengths.Due to these unique properties,we can also realize high-performance and infrared photodetectors based on PN junction.Our structure of graphene-Cu3-x P heterojunction is relatively simple and own high compatibility with traditional silicon-based technologies.Thus,our photodetector have the potential to realize low-cost,high-efficiency commercial applications.2.Pt S2-Pt Se2 van der Waals heterojunctions for efficient and broadband photodetectionWe studied Pt S2-Pt Se2 vertical heterojunction photodetector.This van der Waals heterojunction array is grown in situ on a silicon substrate by a two-step chemical vapor deposition method.Under zero bias voltage,high responsivity(361 m AW-1),high external quantum efficiency(84%)and broadband response wavelengths(405 nm~2200 nm)were achieved in this van der Waals heterojunction photodetector.Combing the theoretical simulation and experiment characterization,we found that the bandgap of the heterostructrue slightly changed,which provide the basis for the photoelectric mechanism.The large-area fabrication method and efficient photodetector performance provide a feasible solution for the commercialization of heterojunction photodetectors based on low-dimensional materials.