Raman Spectroscopy Residual Stress Measurement Method For ZnO

Zinc Oxide(ZnO) is the third-generation semiconductor materials with wide band gap, high exciton binding energy. At the same time, it has found wide extensive application prospects in many areas, such as piezoelectrics, gas sensor and pressure-sensitive sensor. Nevertheless, residual stresses always introduced into ZnO when the material produced. Such residual stresses may affect ZnO structure and devices performance and reliability. Thus, measurement and control the residual stress may play severely entangled roles in the manufacturing process for zinc oxide structure or devices. It is important to stress in the manufacturing process for ZnO structure or devices. Micro-Raman spectroscopy is an effective stress measurement technique, currently the measurement of stress are assumed to be in uniaxial or biaxial stress state for ZnO material, but in many practical applications, shear components of the stress tensor may play a critical role in reliability of ZnO structure. In this paper, aiming at residual stress measurement in ZnO devices by micro-Raman spectroscopy technology carried out the research of ZnO material residual stress Raman measurement theory and technology.In this paper, a Raman stress measurement theory suitable for ZnO material was investigated, analytical mathematical expressions for the relationship between the Raman shift and the stress was deduced. Meanwhile, micro-Raman spectroscopy method was introduced to detect using zinc oxide material A1(TO), E1(TO), E2(low) and E2(high) four vibration modes of Raman shift- stress coefficient experimental measurements. Giving the quantitative relationship between σ 、σ 、σ or σ 、σ 、σ stress component and Raman shift. A set of applicable tension/compression loading device was developed for micro-Raman spectrometer microscope, which can be achieving load display, such as, displacement, force, and collecting Raman scattering spectral information at the same time.Measurement of the Euler angles of wurtzitic ZnO by Raman spectroscopy was deduced. Based on the polarization selection rule and coordinate transformation theory, a series of theoretical formulas regarding the Euler angle measurement for wurtzite crystal using Raman spectroscopy were deduced. The specific experimental processes were given. The measurement of the Raman tensor elements and Euler angles of a ZnO crystal were achieved. The results show a trigonometric functional relationship between the intensities at each Raman band of wurtzite crystal and the Euler angle, , under different polarization configurations. Fitting the curves of measured Raman intensity vs., the Raman tensor elements and Euler angles(φ, ) can be obtained. There is also a trigonometric functional relationship between the intensities at each Raman band and the polarization direction of incident light, which can be used to measure the Euler angle, θ. The experimental results show that the method proposed in this paper can effectively realize the measurement of Euler angles for wurtzite crystal. Our investigations provide the approach for the measurement of crystal orientation on the micro scale.The residual stress distribution around the triangular indentations were measured and analyzed for ZnO single crystal by using micr-Raman spectroscopy. Then the information of Raman shift, WHM and intensity around the indentions was obtation by using field scaning imaging technique. The results show that parallel to the [0001] direction of the border bent toward the outside direction indentation, and parallel to the [1100] direction indentation surrounded accumulation phenomenon which may be due to the hardness of the ZnO crystal than the [0001] direction is twice as large as a result of the [1100] direction. In the heap of indentation is compressive stress.