【摘要】 超声检测技术与原子力显微技术相结合,构成原子力声显微镜(AFAM),能够实现样品内部纳米结构的测量,并分析如局域弹性模量、刚度等力学性能.本文在传统的原子力显微镜(AFM)的基础上初步构建了AFAM,利用AFM轻敲模式下的微悬臂梁振动激励信号来驱动样品背面的压电超声换能器,并利用轻敲模式控制系统中的锁相环检测经过样品后由探针收集的振动信号,形成振幅及相位图像.这种AFAM方法不需外接信号发生器、锁相放大器及相关控制电路,从而避免AFM内、外部的仪器及控制电路的不同步而引起的AFAM振幅/相位与形貌图像间的偏移.此外,还分析了形貌结构对AFAM振幅图像的影响,为进一步研究AFAM亚表面成像奠定了基础.更多还原

【Abstract】 Atomic force acoustic microscopy(AFAM),which combines the techniques of ultrasonic detection and atomic force microscopy(AFM),can detect the nano structure inside the sample and measure the mechanical properties such as elastic modulus and contact stiffness.In this paper,a simple method for constructing AFAM based on conventional AFM is presented.The cantilever oscillation excitation module in tapping mode AFM is used to drive the piezoelectric ultrasonic transducer,which is attached to the bottom of the sample.The ultrasonic oscillation passing through the sample is collected by the probe.The detected probe responses are finally analyzed using the phase-locked loop embedded in the tapping mode controller.This approach requires no additional instruments,such as signal generator and lock-in amplifier,thus the system is much simplified.The offsets between amplitude/ phase and topography images,which are caused by the mismatch in the interior and exterior control circuits,can also be eliminated.In addition,the influence of topography cross-talk on the AFAM amplitude is analyzed.Experimental results demonstrate that the measurement is reliable,which can provide a basis for the further investigation of subsurface imaging via AFAM.更多还原