Study On The Fluorescence And Laser Properties Of GaN,CsPbBr₃ Micro/Nano Structure

Wide bandgap semiconductor materials are also called third-generation semiconductor materials,and their bandgap is greater than or equal to 2.3 e V.Represented by GaN,which has triggered the revolution in human semiconductor lighting technology.Semiconductor perovskite is a type of wide bandgap semiconductor optical material with good electro-optical properties developed in recent years,and has potential applications in solar cells,light-emitting diodes?LEDs?,lasers,etc.This article focuses on these two optical materials and explores their fluorescence and stimulated radiation characteristics from the theoretical and practical perspective.The main contents can be divided into the following four aspects:?1?Based on the finite element method?FEM?,we used COMSOL Multiphysics 5.4 to solve the Helmholtz equation,and the resonant frequency,near-field optical mode and Q factor of the corresponding mode in the GaN optical resonator with a specific shape were obtained.The influence of the rounded passivation effect of the two-dimensional hexagonal GaN optical microcavity cavity on the optical mode and Q factor of the cavity is studied;The change process of the optical mode and quality factor in the cavity caused by the gradual change of the cavity shape from the stadium to the circle in the GaN two-dimensional irregular stadium-shaped chaotic optical microcavity is simulated.?2?The GaN two-dimensional quasi-semicircular soft-chaotic optical microcavity was constructed.Based on nonlinear dynamics,the optical resonance model was constructed in the phase space to predict the possible optical modes in the cavity.The finite element analysis software COMSOL Multiphysics 5.4 was used to simulate the near-field optical mode in the microcavity.The quasi-semicircular GaN optical microcavity was fabricated using semiconductor micro/nano processing technology.Laser experiments show that at higher pump power,due to mode competition,the quasi WGM mode dominates the lasing spectrum,which corresponds to the theoretical simulation results.?3?We investigate the optical property differences between CsPbBr₃@SiO₂quantum dots?QDs?and CsPbBr₃QDs.The photoluminescence demonstrates that CsPbBr₃@SiO₂QDs and CsPbBr₃QDs have similar exciton binding energy.Both CsPbBr₃and CsPbBr₃@SiO₂QDs present optical bandgap and photoluminescence?PL?linewidth broadening as the temperature increases from 10 K to room temperature,which is attributed to the thermal expansion and electron-phonon coupling.The fitting results show that CsPbBr₃and CsPbBr₃@SiO₂QDs have the similar bandgap thermal expansion coefficient,but the CsPbBr₃@SiO₂QDs have weaker electron-phonon interaction.Temperature-dependent time-resolved photoluminescence?TRPL?demonstrates that the PL lifetime increases with the temperature and CsPbBr₃@SiO₂QDs have longer PL lifetime than CsPbBr₃QDs after 110 K.In addition,the CsPbBr₃@SiO₂QDs integrated on the blue light-emitting diode chip as green phosphor material show better thermal stability in air ambient.?4?The triangle cross-section CsPbBr₃microrod with high crystal quality was prepared by chemical vapor deposition.Temperature-related photoluminescence experiments measured the exciton binding energy of this microstructure;The synergistic modulation effect of lattice thermal expansion and electron-phonon coupling effect on the optical band gap is analyzed;The photoluminescence linewidth broadening is attributed to the electron-phonon coupling effect.Time-resolved photoluminescence experiment shows that the lifetime of CsPbBr₃microrods becomes longer with the increasing temperature due to the thermal dissociation of exciton.In addition,we explored the lasing behavior in this CsPbBr₃microrod.The microrod can generate single-mode lasing at a higher pump power.The lasing mode is analyzed by finite element analysis.The lasing mode is a F-P like mode consisting of partial reflection on the side of the cavity and total reflection on the bottom.