薄膜界面粗糙对双晶摇摆曲线的影响

EFFECT OF ROUGHNESS OF MULTILAYER INTERFACE ON THE DOUBLE-CRYSTAL X-RAY DIFFRACTION ROCKING CURVES

用X射线衍射动力学理论,模拟计算InP衬底上InGaAs/AllnAs超晶格和InGaAs单层膜的X射线双晶摇摆曲线,计算结果表明:薄膜界面粗糙对单层膜的衍射峰和超晶格的零级衍射峰影响较小,但却明显影响单层膜衍射干涉条纹和超晶格的±1级卫星峰,随着平均界面粗糙度的增大,单层膜衍射干涉条纹强度减弱并趋于消失;超晶格的±1级卫星峰变弱并逐渐展宽,理论计算的模拟双晶摇摆曲线与超晶格实验曲线比较表明:高质量匹配In_(0.53)Ga_(0.47)As(85A)/Al_(0.48)In_(0.52)As(85A)/InP超晶格样品的界面间存在约一个原子层的平均界面粗糙度。

Based on X-ray dynamical theory, the double-crystal diffraction rocking curves for In-GaAs/InP single layer and InGaAs/AlInAs/InP superlattice were calculated for both perfect and rough interfaces. It is shown that the effect of roughness of multilayer interface on the zero-order diffraction peak was not obvious but severe on both the satellite peaks for superlattice and the interference fringes for single layer structure. With the increasing of the interface roughness, the intensities of interference fringes were reduced and disappeared. And for the satellite peaks, their intensities were reduced and the full width at half maximum broadened. Comparing the experimental result with the calculated one, we believe that there still exists an average roughness of about one monoatomic layer at the interface of high quality InGaAs/Al-InAs/InP lattice-match superlattice sample.