Oxford Instruments-TDI develops new technique for fabrication of InGaN LEDs
October 23, 2008--Green, blue, and violet light-emitting diodes (LEDs) based on III-nitride compounds are typically fabricated using indium gallium nitride (InGaN) alloys in active region of the optoelectronic devices. Most of these materials are grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). Oxford Instruments(OXfordshire, England) subsidiary TDI (Silver Spring, MD), has recently advanced the hydride vapor-phase epitaxy (HVPE) technology as applied to the growth of InGaN. The HVPE process is best known for its capability to grow low-defect, crack-free, high-quality quasi-bulk GaN and aluminum nitride (AlN) materials at a significantly high growth rate of up to 100 µm/hour.
Based on a GaCl3-InCl3-NH3 system, the new HVPE technique developed by the team at Oxford Instruments-TDI is able to precisely control the growth rate of InGaN down to 1-2 µm/hour the the indium content of up to 43%.
A technique called X-ray diffraction reciprocal space mapping (RSM) is used to study the strain relaxation of the InGaN layers. The studies show that low In-content InxGa1-xN (where x is approximately 0.08 to 0.15) layers were either fully strained or partially relaxed, with relaxation strongly depending on layer thickness and full relaxation for higher In-content layer (where x is approximately 0.2 to 0.4). The results were recently presented at the Second International Symposium on Growth of III-Nitrides in Izu, Japan and the 2008 International Workshop on Nitride semiconductors in Montreux, Switzerland.
"This study further confirms the ability of HVPE to grow high-quality InGaN layers and extend its capability
for blue-green LED production in the near future," commented Alexander Syrkin, deputy director
and team leader for the InGaN project at TDI.
Recently, the study on the growth of InGaN by HVPE at Oxford Instruments-TDI was rewarded with a substantial funding from a US government agency. "We are very excited and honored to be part of the U.S. government research program. We strongly believe that we are just at the edge of discovering the substantial potential of the HVPE technology for the solid-state lighting industry in the near future," commented by Bernard Scanlan, general manager at Oxford Instruments-TDI.
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