Acquisition of a Tandem High-Resolution X-Ray Diffractometer-Photoluminescence System
Abstract:
A high-resolution x-ray diffractometer HRXRD with triple axis diffraction capabilities, combined in a single unit with a photo luminescence PL system has been acquired. This instrument combines complementary structural and optical characterization methods that will enhance ARO-funded research involving growth and defect-control studies of highly lattice-mismatched III-VIV heterostructures. The HRXRD capabilities include double and triple axis diffraction, asymmetric and grazing incidence reflectivity, x-ray topography, and fluorescence. The PL capabilities include variable temperature measurements and lateral mapping of optical properties. PL and HRXRD analyses are possible at the same position, allowing for correlation between optical and structural properties. This system is installed and operational in a dedicated facility for this purpose. Measurements to understand how defect control methodologies impact properties of lattice-mismatched heterostructures are underway. For our ARO-supported research involving III-V growth and integration onto Si via relaxed compositionally-graded GeSi buffers, this instrument is being used to investigate the outstanding issues related to mismatched heteroepitaxy of III-arsenides, III-phosphides, LTG low temperature grown III-Vs and on group IV substrates. These include quantifying the degree and distribution of lattice strain and relaxation in multiple layers, lattice tilt, composition, bandgap, interface and surface roughness, thermal expansion effects, mosaic spread, etc.