Synthesis And Electronic And Photoelectric Properties Of Indium Selenide Nano Films

Two-dimensional?2D?semiconductors are hot field of research in materials and microelectronics due to their unique physical and chemical properties,which are different from their bulk materials,making their huge potential application in nanoelectronic devices and nano-optoelectronic devices.However,stable and highperformance semiconductors are needed to be further explored.Indium selenide,including InSe and In₂Se₃,are typical II?-?I group layered semiconductors.Bulk InSe and In₂Se₃ display good stability,high electron mobility and high light absorption coefficient,making great potential application in high performance electronic and optoelectronic devices.Up to now,research on 2D indium selenide still be limited and lots of properties should be further investigated.Herein,synthesis methods of 2D indium selenide are investigated and the field effect transistors?FETs?and phototransistor based on InSe are fabricated.The transport and photodetection properties of multilayer InSe are explored.The InSe-CuInSe₂ lateral heterojunctions are fabricated and its electronic and photovoltaic performance are investigated.The strain sensors and e-skin devices based on 2D In₂Se₃ are fabricated,and their performance of monitoring human activity are systematically investigated.2D ?-InSe nanoflakes on various substrates are fabricated by mechanical exfoliation method.The relationship between Raman/PL spectrums and InSe thickness are explored.The multilayer InSe field-effect-transistors?FETs?are fabricated and the electronic transport properties are investigated.The performance of multilayer InSe FETs is comparable to monocrystalline silicon electronic devices.The electronic transport performances of InSe FETs with various electrodes?Al,Ti,In and Cr?are consistent with the surface roughness of electrodes rather than metal work function.The results of experiment and theory simulation demonstrate that contact resistance between metal electrode and 2D InSe is determined by number of electron in d orbital.The metal Cr is good metal electrode for 2D InSe nanoflakes.The instability in InSe FETs is totally different between in air and vacuum conditions after applying gate-bias.These results demonstrate that gate-bias induced instability in InSe FETs is attributed to adsorption and desorption process of oxygen and/or water molecules on the InSe surface controlled by gate-bias.The electronic transport performance of InSe FETs with various dielectric materials is investigated.The PMMA/oxide double layer dielectrics can significantly improve the electronic transport performance of InSe FETs.The results of surface roughness and contact angle measurement indicate that coulomb impurities scattering?CIs?and surface polar phonon scattering?SPP?from oxidized dielectric can be effectively suppressed by PMMA layer.The model of multiple reflection-adsorption process of the light adsorption in multilayer InSe is established.The theoretical simulation demonstrates that the light adsorption in InSe is nonlinearly depended on thickness of InSe.Multilayer InSe phototransistors are fabricated and the photodetection performance is investigated.Multilayer InSe phototransistor shows broad photodetection range under various illumination wavelengths and intensities.The ultrahigh photoresponse is confirmed by calculated responsivity and detectivity.Flexible InSe photodetector shows a good stability under multi-cycle bending.A new method for the fabrication of InSe-CuInSe₂ lateral p-n heterojunction by solid-state-reaction is developed.The electronic and photovoltaic performance of InSe-CuInSe₂ lateral p-n heterojunction are investigated.The ?-? curve of diode based on InSe-CuInSe₂ lateral p-n heterojunction displays significant rectification effect.The calculated ideality factor is 1.3 and demonstates that the rectification current is dominated by diffusion current.This heterojunction also possesses significant photovoltaic effect and light-power conversion efficiency of 3.5% under light illumination.A new method for the synthesis of 2D ?-In₂Se₃ thin films by atmospheric pressure chemical vapor deposition is developed.The lateral size of few layer In₂Se₃ thin films is 100 ?m on mica.The growth mechanisms of 2D ?-In₂Se₃ on different substrates are explored.Various large-scale and patterned In₂Se₃ thin-films are successfully fabricated by tuning surface morphology of mica.The strain sensor and sensor arrays based on 2D In₂Se₃ thin-film are developed and its application to monitor human actions is explored.2D In₂Se₃ thin-film shows significant piezoresistive effect and good stability under various tensile and compression stress.The flexible and wearable strain sensor and sensor arrays based 2D In₂Se₃ thin-film are fabricated and performance of monitoring human activities is investigated.The results clarify that 2D In₂Se₃ strain sensor shows high sensitivity and good stability for human activities,and sensor arrays show good spatial resolution on conformal surfaces.This thesis has enriched the synthesis methods and electronic and optoelectronic properties of InSe/In₂Se₃ nanoflakes,paving a way for InSe/In₂Se₃ application in high performance electronic devices,optoelectronic devices and strain sensors.