High resolution x-ray diffraction (HRXRD)

The high resolution X-ray diffractometer (Bede D1) facility is supported by NCU center for science and technology as shown in the below figure.

HRXRD1

The interior part sketch and the real facility are shown in the below figure. The monochromator are composed of two crystals, which has two channels for each crystal for different measurement mode.

HRXRD2

Two major modes of HRXRD employed in our work are rocking curve and reciprocal space mapping (RSM) measurements. Both of two modes are based on Bragg diffraction equation:

HRXRD3

, where d is the (100) plane spacing for silicon substrate, θ is the angle between incident plane and the surface plane, n is an integer, λ is 1.54Å, which is the wavelength of monochrome incident X-ray with copper material.

HRXRD4

Strain is analyzed using X-ray diffraction around the (004) ω-2θ rocking curve scanning. If the film of interest is uniformly distributed, the strain can be calculated from the change angle with respect to the substrate, Δθ. It is determined with taking the Δθ into the derivative of the Bragg equation:

HRXRD5

In addition, the Bede RADS Mercury software is utilized to dynamically simulate the strain distribution profile.

When reciprocal space mapping mode is applied, the loop scanning is used and the reciprocal space mapping is constructed by adding all the loop scan result to determine whether the lattice structure is psuedomorphic or not, shown as below figure.