MOVPE growth of InGaN on sapphire using growth initiation cycles

Abstract

The worldwide demand for ultra-high-brightness blue and green light emitting devices (LEDs) has driven the development of metalorganic chemical vapor deposition (MOCVD) for Al-Ga-In-N alloy systems towards efficient multiwafer technology. This new MOCVD approach has been developed using a unique growth initiation cycle which provides material of superior quality and increased lateral thickness uniformities in the 7 × 2″ to 15 × 2″ Planetary Reactor ®, which is to our knowledge the largest Nitride MOCVD reactor in the field of successful production of blue LEDs. The MOCVD process, based on a laminar radial two-flow approach will be discussed in detail. The design provides material with abrupt interfaces, also while using different substrates like Al 2O 3, SiC, Si. Wafer rotation is performed by means of Gas Foil Rotation ®. For proper growth initiation for blue-green LED material it is essential that heating from room temperature to 1000 °C can be done in less than 2 min and the cool down from 1000 to 500 °C takes place in 3 min. The growth initiation cycle has been demonstrated to yield device quality GaN with X-ray full width at half maximum (FWHM) of 30 arcsec and excellent photoluminescence (PL) uniformity. Key to the excellent results is the high flexibility of this unique MOCVD process that can be used between 10 and 1000 mbar, a variety of total flow rates 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 allows to adjust the required growth rate and to obtain the necessary control on In composition in InGaN with the successful demonstration of blue LEDs.