International Symposium on Blue Lasers and Light Emitting Diodes 2006 15 th – 19 th May 2006, Montpellier, France Benoit Guilhabert Institute of Photonics, Strathclyde University, 106 Rottenrow, Glasgow G4 0NW. 1. Introduction Ten years after the first symposium, the fifth meeting in this series allowed over 200 scientists from many countries to exchange their knowledge and discuss future trends in wide bandgap semiconductor science and technology. Applications do not lag behind the science, as many companies are developing laser diodes (LDs) and light emitting diodes (LEDs) of brightness and efficiency to match, or compete strongly against, commercial requirements. Great improvements in the crystal quality have been achieved using different kinds of growth reactors. Moreover, there is now a real interest in increasing device efficiency, either by increasing the internal quantum well efficiency (through refinements in growth and structure design), or by improving extraction efficiency. These two contrasting approaches will form the structure of this conference report. In the first part, I will consider developments in growth techniques and materials. In the second part, I will focus on approaches to improved light extraction, and issues in device reliability. Throughout I have highlighted particularly significant oral presentations, rather than attempting a survey of the many posters and contributed oral presentations at the meeting. 2. Growth techniques and materials: The classical methods to grow III-V crystals are Metalorganic Chemical Vapor Deposition (MOCVD) and Molecular Beam Epitaxy (MBE). Since the early 1990’s, MOCVD has been the dominant growth method for high-efficiency III- nitride optoelectronic devices. A variant on MOCVD, Migration Enhanced Metalorganic Chemical Vapor Deposition (MEMOCVD) has led to breakthroughs in growth of AlN/GaN/InN based heterostructures in the group of Prof M.A. Khan 1 . MBE has met success more recently with the growth of LDs offering continuous wave (CW) room temperature operation 2 . Such devices, shown on figure 1, work at a current threshold of 5.7 kA.cm -2 and voltage of 8.6 V in CW operation at room temperature. The device performance and lifetime are still limited though, owing to p-doping issues, and the complex tradeoffs involved in LD design.