Depth-dependent x-ray diffraction using extremely asymmetric reflections

Investigations of semiconductor heterostructures by x-ray diffraction are characterized by the absence of any direct depth information in the scattering profile. This paper demonstrates a new method of obtaining depth-dependent information about heterostructures by x-ray diffraction. The distances involved here are limited by the absorption of the x-rays in the material. The absorption depth can be varied continuously for asymmetric reflections by rotating the sample around the scattering vector. Two different methods for this rotation as well as experimental set-ups are discussed. We present experimental results that conclusively demonstrate the usefulness of depth-dependent measurements. The data can be used directly for the improvement of semiconductor devices.