Novel RPCVD Growth Improves BluGlass`s GaN Film Quality
Sydney-based firm BluGlass says it has advanced its proprietary RPCVD technology and is now producing high quality GaN at low temperature on a commercial MOCVD GaN template. Transmission Electron Microscopy (TEM), performed by a third party, has revealed that BluGlass's latest Remote Plasma Chemical Vapour Deposition (RPCVD) growth technology has minimised impurities to within industry acceptable limits. The Australian-based firm says that the TEM report confirms an impressive microstructure with a defect density comparable to commercial MOCVD grown with a GaN underlying template. BluGlass reckons that its low defect density highly crystalline material grown at low temperature is a breakthrough, and is essential in demonstrating that its RPCVD method is commercially viable for LED chip growth. The firm believes its flexible RPCVD technology, because of its low temperature, offers manufacturers many potential benefits including higher efficiency, lower manufacturing costs and greater scalability. The superior material quality has been achieved partly due to reducing trace amounts of chemical impurities incorporated in GaN films during growth. In the past, BluGlass research has been limited by the presence of two impurities which were severely affecting material quality; oxygen and carbon. Through hardware upgrades and process changes, oxygen impurities have been reduced to almost commercially acceptable levels and the firm says the material is no longer a hindrance to material quality. BluGlass says that carbon impurities are also being reduced towards industry acceptance with its new growth approach. BluGlass CEO, Giles Bourne comments, "These achievements demonstrate, for the first time, that high crystalline GaN films can be grown at low temperature using RPCVD. This is a critical step in proving to industry the potential of breakthrough technology. A low temperature commercial process would have been truly exciting implications for the LED industry. It has the potential to offer significant advantages for both device performance and low cost manufacturing." The company is now focussing on tweaking the process to reduce the impurities to within industry accepted limits. The successful reduction of these impurities should enable BluGlass to achieve, in the short term, two main milestones. The first is to produce films with properties similar to MOCVD grown films with industry accepted electrical properties. The company is also striving to improve device efficiency and confirm the competitive advantages of its RPCVD process. BluGlass believes that achieving these targets will lead to customer engagement and the placing of a demonstration tool with a leading LED manufacturer. A basic LED is composed of multiple semiconductor layers. Low defect density, or high crystalline quality, are critical in order to achieve the necessary device performance for commercial applications. Attaining a low defect density is vital in improving device performance. TEM images illustrating the low temperature RPCVD top GaN layer are shown below in Figures 1 and 2. BluGlass says the defect density is not generally higher than those observed in a typical underlying high temperature, commercial MOCVD GaN template. BluGlass adds that this dramatic improvement for RPCVD is largely due to the reduction of impurities incorporated in the GaN layer during growth. As its technology team continues to further reduce impurities, BluGlass is aiming to file patents for its novel RPCVD technology in the near future.