Carrier Recombination Dynamics And Optical Properties Of InGaN MQW Nanorods

?-nitride semiconductors(InN?GaN?AlN),have continuously tunable optical band gaps from 0.7e V to 6.2e V,corresponding wavelengths covering a wide spectrum range from near infrared to ultraviolet.In the 1990s,since the invention of the first high brightness blue photodiode,researchers from all over the world have carried out a series of research on group ? nitriding materials and optoelectronic devices,and a series of scientific research results have emerged.In 2014,three Japanese scientists,Akasaki?Amano and Nakamura,were awarded the Nobel Prize in physics for their great contributions to the growth of gallium nitride materials and the application of light-emitting diode devices.In the 21st century,?-nitride semiconductors have a very broad prospect in solid-state lighting?full-color display?visible light communication?UV detectors and other applications.In this thesis,electron beam lithography(EBL)and etching technology were used to fabricate InGaN MQW epitaxial wafers,and obtain InGaN MQW nanopillar LED array structure.At the same time,a physical model of carrier diffusion and recombination is proposed to explain the linear relationship between the cylindrical structure and carrier lifetime,which reveals the physical process of InGaN multi quantum well LED.In addition,combined with the experimental data,the influence of nano structure on the optical properties of nanorod LED is further explored.The main contents of this paper are as follows:1.Firstly,we spin coated a layer of HSQ photoresist on InGaN MQW LED epitaxial wafers.Then,a circular hole pattern is formed on the photoresist surface by EBL.The diameter of the circular hole can be adjusted by setting the layout parameters of EBL.Then,inductively coupled plasma(ICP)was used to etch the quantum well samples from top to bottom.The etching height was determined by the concentration time of ICP atmosphere.Finally,the position size controllable and periodic arrangement of InGaN MQW nanopillar LED light-emitting devices are obtained.2.Based on the basic carrier transport equation and considering the effect of surface recombination,a three-dimensional carrier transport model for InGaN MQW nanopillar LED is established.On this basis,the relationship between the minority carrier lifetime and the diameter of the nanopillar is studied.The results show that under the condition of low surface recombination rate,the minority carrier lifetime has a linear relationship with the diameter of the nanorod.At the same time,based on the study of exciton recombination dynamics in InGaN Quantum Well,the distribution of carriers in different exciton emission centers with the change of nano column diameter is well explained,combined with the stress release effect of nanorod.3.The influence of nano structure on the optical properties of InGaN MQW nanorod LED was studied,and the optical characterization and analysis were carried out.The results show that the PL peak position of InGaN Quantum Well nanopillar LED firstly shows blueshift and then redshift with the decrease of diameter.With the increase of the diameter,the carrier begins to transfer from the shallow localized exciton to the deep localized exciton.Compared with the samples of low In component,the carriers of high In component samples are more easily bound to the exciton emission center of deep localized state.In addition,a layer of Si O₂ film is deposited on the sidewall of InGaN MQW nanorod LED,which has been proved to effectively improve the luminous efficiency and far-field light distribution uniformity.