Research On Construction And Sensing Characteristics Of Electrically-pumped GaN LED Opto-mechanical Accelerometers

Micro-Optical Electro-Mechanical System（MOEMS）accelerometers are widely used in fields such as automobiles,aerospace,and electronic consumption due to their high resolution,electromagnetic interference resistance,and environmental adaptability.However,MOEMS accelerometers are difficult to balance high precision and large range,and most MOEMS accelerometers use Si or Si N materials,which cannot emit light and require the introduction of external light sources.This greatly limits the integration and development of accelerometers.In response to the above issues,this article combines the excellent optical,electrical,and mechanical properties of GaN to design and produces an electrically-pumped GaN LED beam accelerometer.The light source and sensing components are combined to avoid the introduction of external light sources,which can achieve high-density optoelectronic integration.The research content of this article is divided into three parts:1.Research on the optical mechanical sensing characteristics of optically-pumped GaN optical microdisks.Optical-pumped LED suspended disks with diameters ranging from 10μm to 25μm are designed and produced using micro/nano processing technology.Mechanical analysis is conducted using COMSOL simulation software to discuss the stress strain and displacement deformation of devices with different sizes under gravity and rotation conditions,as well as horizontal and vertical directions.Combined with experimental spectra,the corresponding relationship between the optical pumping laser peak of the device and the mechanical strain of the micro disk is found,A sensing mechanism for mechanical strain and spectral shift is established.2.Based on the research of optically-pumped micro disk accelerometers,an electrically-pumped In GaN quantum well suspended wheel shaped micro disk LED device with a radius of 75μm is designed and produced.Under the same mechanical field conditions mentioned above,COMSOL simulation is conducted on the device.Through comprehensive comparison,it is found that the displacement and deformation patterns of the device in the vertical direction（Z direction）is obvious.Combined with the electroluminescence（EL）spectrum of the device,we find the sensing relationship between the Z-direction displacement of the device and the blue shift of the EL spectral peak center,and discuss the mechanism behind it.3.In order to improve the sensitivity of the accelerometer,an In GaN quantum well LED beam photomechanical accelerometer is designed and produced.The photomechanical strain of the beam structure microcavity is more sensitive than that of the circular microcavity,making it more suitable for high-precision measurement of acceleration.In the experiment,two types of electrically-pumped GaN LED mechanical sensing elements（Type I and Type II）based on the beam structure are designed and produced,and the optoelectronic characteristics of the devices is tested.Relationship between the blueshift of the electroluminescence（EL）spectra and the deformation of GaN beam structure based on the QCSE of In GaN quantum well（QW）structure is studied via introducing an extra mass block（type II accelerometer）.Under the equivalent acceleration condition,in addition to the elastic deformation of GaN-LED,there is a direct relationship between the spectra shift of LED and the magnitude of acceleration.The extra mass block(gravitational force:75.5×10^-12 N)induced blueshift of the EL spectra is obtained and shows driven current dependency.A polymer sphere（PS;gravitational force:3.427 p N）is placed at the center of the beam GaN-LED,and a blueshift of 0.061 nm is observed in the EL spectrum under the injection current of 0.5 m A.The maximum sensitivity of the acceleration is measured to be 0.02 m/s²,the maximum measurable acceleration was calculated to be 1.8×10⁶ m/s².It indicates the simultaneous realization of high sensitivity and broad measurement range of acceleration.This indicates that this study achieve the requirements of high sensitivity and wide measurement range of the accelerometer,and the accelerometer produced achieve opto electromechanical integration and is easy to integrate.This work is of great significance for on-chip accelerometers,including optical force measurement and inertial navigation systems with high integration capabilities.