Study Of Electrostatic Comb Driver Used For Movable GaN Micro Mirror

Movable micro mirror based on micro electro mechanical system(MEMS) has a good application prospect in the fields of optical communication, optical computing, projection display, optical imaging and so on. As a driving mechanism, micro driver provides the key technology support for the tunable micro mirror. In recent years, micro driver in the design of the structure has been more mature, but the use of materials is still relatively simple. GaN as the third generation semiconductor materials, is a kind of ideal short wavelength light-emitting materials. Compare with the Si, GaN has different physical properties, so the GaN integrated into silicon based optical micro electromechanical system and preparation of new micro system or optoelectronic devices can be further expanded the scope of application of MEMS devices. Driven by electrostatic comb micro actuator is a excellent performance driving way, with no hysteresis, rapid response, dynamic range, etc., and it has the most widely used.An electrostatic comb driver used for a movable GaN micro mirror is proposed. Firstly, an overview of the development status and application of the MEMS is recommended, presenting the relevant background and significance of the issue and the chacacteristics of GaN. The principle and challenge of electrostatic actuators is elaborated. By using FEM software, a steady physical model was constructed for the movable GaN micro mirror actuated by the electrostatic comb driver and then the structure(the length and width of the comb, comb figures, bearig beam, mirror radius, the gap between comb fingers) of the comb driver is optimization. The driven displacement is 1.93 μm under 200 V driving voltage. Then the modal of the device is simulated and analyzed, and the first six order modes and the corresponding resonant frequency are obtained, and the motion of each mode is described.Besides, the sample is fabricated based on Micro Electronic Mechanic System(MEMS) process and the driving characteristic of the electrostatic comb driver is investigated. The result demonstrates that the displacement of the driver has a quadratic relation with the drive voltage which is consistent with the theoretical analysis. The displacement of the proposed micro actuator is 1.08 μm under a dc driving voltage of 200 V.