Advances in InGaN technology for light-emitting diodes and semiconductor lasers

Abstract

The past ten years have seen a virtual revolution for the optoelectronics industry dealing with LEDs. With the development of new III-V materials, such as AlGaAs, AlInGaP, and InGaN, and epitaxial structures capable of very efficient visible light generation, a vast new field of applications for LEDs has opened. The most recent development has been the introduction of bright blue and green LEDs based on InGaN. This now makes coverage of the entire color spectrum possible, from red to violet at brightness and efficiency levels exceeding conventional filament light sources. Full-color large screen video displays with excellent color rendition and brightness and even white light LEDs are being produced. Semiconductor lasers have also benefitted from progress with InGaN technology, and have been demonstrated with emission wavelengths around 400 nm. The primary importance of these devices is in the area of CD data storage, where the short wavelength increases storage density by approximately a factor of four over current systems using a red AlInGaP or infrared AlGaAs laser. Despite these advances, we have barely begun to see the possibilities for LEDs. Continuing improvements in materials and device efficiency and light extraction techniques are set to raise performance limits by at least a factor of two for InGaN and AlInGaP devices over the next few years. This presentation focuses on the advances that have been achieved with InGaN materials technology and the types of devices that have been created. Current applications and possible future use for high performance blue LEDs and lasers are also discussed.