异质外延错向角的X射线精确测量方法

A PRECISE METHOD FOR MEASURING TILTS IN HETEROSTRUCTURES BY X RAY DIFFRACTION

通过分析外延层与衬底之间存在错向角时的衍射圆锥，利用简明的衍射几何关系提出了一个测量外延层与衬底之间错向角的方法及相应的计算错向角的公式，同时提出了检验办法。设计了一个有两个外延层的ＩｎＧａＡｓ／ＩｎＡｌＡｓ／ＩｎＰ样品，用高精度ｘ射线四晶衍射仪，对样品进行了衍射测量，并应用提出的方法精确地测出了两个外延层各自与衬底之间的错向角以及两个外延层之间的错向角，所得结果和理论预期值完全一致。本文也指出，采用常规的ｘ射线双晶方法的旋转１８０度两次测量法，根据衍射峰间距所测量的错向角为实际值的下限。

Strained semiconductor microstructures are one of the most attractive and important materials for both basic study and device applications. Lattice mismatch and misorientation are common in the strained semiconductors, while there are still some problems with measurement of misorentation in the epilayers by conventional method of x ray diffraction. In this paper, a method of x ray diffraction with simple geometry was developed to quantitatively analyze the structure of strained epilayer with a tilting angle to the substrate. An X′Pert four crystal x ray diffractometer with high accuracy (1/10000 degree) and high resolution was used to demonstrate the proposed method on a InGaAs.InAlAs/InP microstructure grown by gas source molecular beam epitaxy. Results showed an excellent consistency between data measured and calculated from the model. It was pointed out that the conventional 180 0 rotation twice measurement method usually got a value smaller than the real value of the tilting angle.