MOVPE GROWTH OF INGAN ON SAPPHIRE USING GROWTH INITIATION CYCLES

The worldwide demand for ultra-high-brightness blue and green light em itting devices (LEDs) has driven the development of metalorganic chemi cal vapor deposition (MOCVD) for Al-Ga-In-N alloy systems towards effi cient multiwafer technology. This new MOCVD approach has been develope d using a unique growth initiation cycle which provides material of su perior quality and increased lateral thickness uniformities in the 7 x 2 '' to 15 x 2 '' Planetary Reactor(R), which is to our knowledge the largest Nitride MOCVD reactor in the field of successful production o f blue LEDs, The MOCVD process. based on a laminar radial two-flow app roach will be discussed in detail. The design provides material with a brupt interfaces. also while using different substrates like Al2O3, Si C, Si. Wafer rotation is performed by means of Gas Foil Rotation(R). F or proper growth initiation for blue-green LED material it is essentia l that heating from room temperature to 1000 degrees C can be done In less than 2 min and the cool down from 1000 to 500 degrees C lakes pla ce in 3 min. The growth initiation cycle has been demonstrated to yiel d device duality GaN with X-ray full width at half maximum (FWHM) of 3 0 arcsec and excellent photoluminescence (PL) uniformity. Key to the e xcellent results is the high flexibility of this unique MOCVD process that can be used between 10 and 1000 mbar, a variety of total flow rat es and extremely precise temperature control and uniformity across the entire reactor and the substrates, by means of a new multicoil heater system. Using all these flexible parameters in the appropriate way al lows to adjust the required growth rate and to obtain the necessary co ntrol on In composition in InGaN with the successful demonstration of blue LEDs. (C) 1997 Elsevier Science S.A.