硅基AlN应力和压电极化研究

Study on Strain and Piezoelectric Polarization of AlN/Si

通过XRD和Raman谱研究了用金属有机化学气相沉积 (MOCVD)的方法在Si( 111)面上生长的AlN薄膜层上的应力和压电极化 ,Raman谱观察到两个声子峰位分别在 619.5cm- 1 (A1 (TO) )和 668.5cm- 1 (E2 (high) )。通过光学声子E2 (high)的频移为 13cm- 1 计算得到AlN薄膜上的双轴压应力为 5 .1GPa ,在z轴方向上和在垂直于z轴方向上的应变分别为εzz=6 7× 10 - 3和εxx=-1 1× 10 - 2 ,产生的压电极化电荷PPE=2 .2 6× 10 - 2 c·m- 2 ,这相当于在Si的表面产生浓度为 1.41× 10 1 3c·cm- 2 的电子积累。同时 ,实验还发现在MOCVD生长过程中存在Si原子的扩散 ,在界面处形成了一个过渡层 ,过渡层主要以Si原子取代Al原子的位置并形成Si-N键为主。

The structural properties of AlN thin film grown on Si(111) substrate by metalorganic chemical vapor deposition (MOCVD) were investigated using X-ray diffraction and Raman measurements. Phonons at 619.5 cm^(-1)(A_1(TO)) and 668.5 cm^(-1)(E_2(high)) were found. The stress and piezoelectric polarization of the AlN film were analyzed with E_2(high) phonon mode frequency shift in Raman spectra. The result indicates that the amount of the biaxial compressed stress is about 5.1 GPa, the strain along the z-axis and perpendicular to the z-axis was calculated i.e., ε_(zz)=6.7×10^(-3) and ε_(xx)=-1.1×10^(-2), respectively. The amount of the piezoelectric polarization is about 2.26×10^(-2) c·cm^(-2), equal to electrons with density of 1.41×10^(13) cm^(-2) on the surface of Si. Phonons of Si-N bonds were also observed accompanying phonons of AlN crystal in Raman spectra, which indicate that Si atoms diffuse into AlN layers during growing and form a transition layer at the interface of AlN/Si, and Si atoms take the place of Al atoms mostly and Si-N bonds are formed.