基于石英音叉探针的原子力显微镜测头开发

摘要

基于石英音叉探针开发了一种自感应原子力显微镜（AFM）测头。该测头通过自身输出电信号检测悬臂振幅变化，无需外部光学检测部件，易于集成。针对测头设计了微弱电流提取及寄生电容补偿电路。利用商业化锁相放大器实现了对测头幅度信号的获取。在此基础上对测头在调幅模式下的力-距离曲线和分辨力进行了测试。利用锁相放大器内置的 PID 模块实现了调幅模式下对样品表面形貌的测量。实验证明，该测头灵敏度为0.624 mV/ nm，分辨力优于2 nm。%A self-sensing atomic force microscope(AFM)measuring head is developed based on a commercial quartz turning fork probe. The measuring head is easy to integrate and it can detect the amplitude variations of the cantilever through the electrical signal instead of using optical detection components. A weak signal detection and parasitic capacitance compensation circuit is designed for the measuring head. The amplitude signal of the measuring head is obtained using a commercial lock-in amplifier. And on this base the force - distance curve and resolution of the measuring head in amplitude modulation mode is tested. Using the PID module in lock-in amplifier,the topography of the sample is measured in amplitude modulation mode. The results indicated that the sensitivity of the measuring head is 0. 624 mV/ nm, and the resolution of the measuring head can reach less than 2 nm.