Seminars & Talks

Recently SemiLEDs Mvp LED, Osram ThinGAN chips, Cree EZbright and LumiLEDs thin film Flip Chip, all employ a vertical structure design to push the LED brightness efficiency to record highs.

In this talk, we will discuss advantages of vertical LED where the original growth substrate (either sapphire or SiC) is removed, leaving a thin LED structure on top of the new host substrate. The choice of new host substrates may vary from Si, Ge, or metal alloy. In the case of Mvp LED, a copper alloy is used because copper exhibits thermal and electrical conductivity that is far better than Si and Ge. Therefore under the same input power, the p-n junction temperature of Mvp LED is much lower than conventional LEDs on sapphire. One challenge, as a result from the removal of sapphire or SiC, for vertical LEDs is to design a good N-electrode on N-face GaN. The reversed polarity of N-face GaN makes many well-known metal system contacts very Schottky. After the optimization of N-contact, the forward voltage for 1 W MvpLED could be as low as 2.9 V, making the efficiency of 100 lms/watt reachable.

October 25, 2005...Two especially notable names in innovative LED chip design, Trung Doan and Chuong Tran, have formed a new GaN-based LED company called SemiLED. The startup is totally USA-funded and headquartered in Silicon Valley, with operations in Taiwan. Our readers know Chuong from his brilliant early work developing blue spectrum LEDs at Emcore in Somerset, New Jersey in the 1990 and his more recent work as one of the cofounders of Highlink in Taiwan. According to Chuong in an exclusive communication with CompoundSemi News and LIGHTimes, "All the credit, however, should go to Trung Doan. He was VP of development at Micron and then VP of Applied Material prior to founding SemiLEDs. Trung holds more than 250 patents and is really an innovation machine." SemiLED made their official launch of their initial product on Monday, October 20th. It’s a GaN-based vertical LED, which the founders call "MvpLED" for"Metal Vertical Photon Light Emitting Diode" citing that this is "a differentiated technology." Details and vivid graphics are included in the company news release