Preparation And Photodetection Properties Of Perovskite/Silicon Nanoporous Pillar Array

Photodetector is a kind of device that can convert incident light signals to electrical signals based on photoelectric effect.It has been widely used in many fields such as industry,agriculture,transportation,aerospace,military,daily life,and so on,among them,semiconductor photodetectors are very significant for their high sensitivity,fast response speed,and esay to integration.With rapid development of semiconductor fabrication technology and emergence of new semiconductor materials,the research on high performance semiconductor photodetector has been paid great attention in recent years.Among the various semiconductor materials explored for light detection,the newly-emerging perovskites are of tremendous interests because of their appealing properties including the large absorption coefficient,low exciton binding energy,bipolar carrier transport characteristics,high carrier diffusion length,and the low-temperature processing method.Note that silicon materials are also usually used to combine with perovskites,which mainly takes into account the possible application of Si-based optoelectronic devices in later integrated circuits.While,one can see that the previous studies on perovskite/silicon photodetectors are mainly based on the planar heterostructures.Thus,the undesirable light reflection at the planar hetero-interfaces will occur,so the maximum absorption of the incident light can't be guaranteed,resulting in a reduced photoresponsivity consequently.Therefore,in terms of the device performance,there are many remaining challenges for such photodetectors.To solve this problem,this thesis focuses on how to combine the advantage of silicon nanoporous pillar array?Si-NPA?and perovskite to form an heterojunction device for excellent on/off photocurrent ratio,responsivity,specific detectivity,response speed,and the stability of device.The detailed works can be described as follows:In this paper,the Si-NPA templates with periodic arrangement and high uniformity are synthesized by hydrothermal method.A one-step solution method is used to grow perovskite thin films on Si-NPA templates.By optimizing the annealing conditions,the thin films with high coverage,low defect density,and conformal growth with 3D templates are achieved.The films properties are further analyzed by the methods of SEM,XRD,absorption spectrum,PL spectrum,and stability test.After sputtering Zn O carrier transport layers and evaporating Ag electrodes,a heterojunction photodetector with a structure of Ag/Zn O/Pervoskite/Si-NPA/In Ga is prepared.Owing to the unique effects of Si-NPA for effectively reducing light reflection,alleviating the lattice mismatch,multiplying the transportation and collection paths of the carriers and improving the stability of perovskite thin films,when using organic-inorganic hybrid perovskite MAPb I₃ as photosensitive materials,the proposed photodetectors demonstrated a broadband photoresponse from the UV-Vis-NIR region,and an obvious photovoltaic effect is observed.Under the light illumination of 780 nm,a high on/off ratio of 0.82×10⁵,a photoresponsivity of 8.13 m A/W,a specific detectivity of 0.974×10¹³ Jones,and fast response speeds of 253.3/230.4?s are achieved at zero bias.What's more,we using inorganic double perovskite Cs₂Ag Bi Br₆ as photosensitive materials for further improve the stability of devices,our device is remarkable with an ultra-fast response of 72.3 ns/68 ns,a high on/off photocurrent ratio of 5.9×10⁵,a photoresponsivity of1.04 A/W,and a specific detectivity of 1.01×10¹³ Jones.In addition,the device reveals outstanding thermal and long-term stability,with negligible degradation of the photoresponsivity after successive operating of 18 hours at high temperatures and storage in open air for 3 months.The experimental results prove the role of Pervoskite/Si-NPA heterojunction in improving the photoresponsivity,response speed,and device stability of devices,which provide new ideas and references for material selection and structural design of high-performance Perovskite/Sillon photodetectors.