We
report growth of InGaN/GaN multi-quantum well (MQW) and LED structures on a
novel composite substrate designed to eliminate the coefficient of thermal
expansion (CTE) mismatch problems which impact GaN growth on bulk sapphire. To
form the composite substrate, a thin sapphire layer is wafer-bonded to a
polycrystalline aluminum nitride (P-AlN) support substrate. The sapphire layer
provides the epitaxial template for the growth; however, the thermo-mechanical
properties of the composite substrate are determined by the P-AlN. Using these
substrates, thermal stresses associated with temperature changes during growth
should be reduced an order of magnitude compared to films grown on bulk
sapphire, based on published CTE data. In order to test the suitability of the
substrates for GaN LED growth, test structures were grown by metalorganic
chemical vapor deposition (MOCVD) using standard process conditions for GaN
growth on sapphire. Bulk sapphire substrates were included as control samples
in all growth runs. In situ reflectance
monitoring was used to compare the growth dynamics for the different
substrates. The material quality of the films as judged by X-ray diffraction
(XRD), photoluminescence and transmission electron microscopy (TEM) was similar
for the composite substrate and the sapphire control samples.
Electroluminescence
was obtained from the LED structure grown on a P-AlN composite substrate, with
a similar peak wavelength and peak width to the control samples. XRD and Raman
spectroscopy results confirm that the residual strain in GaN films grown on the
composite substrates is dramatically reduced compared to growth on bulk
sapphire substrates.
Source:Journal of Crystal Growth
If you need more information about GaAs on 200 mm Si wafers via thin temperature graded Ge buffers by molecular beam epitaxy, please visit our website:http://www.qualitymaterial.net, send us email at powerwaymaterial@gmail.com.
Source:Journal of Crystal Growth
If you need more information about GaAs on 200 mm Si wafers via thin temperature graded Ge buffers by molecular beam epitaxy, please visit our website:http://www.qualitymaterial.net, send us email at powerwaymaterial@gmail.com.
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