LED manufacturing research: RPI integrates features, studies address cost and efficiency
13 Jun 2013
New RPI research proves the concept of integrating LED emitters on the same chip with other electronic components such as transistors, while other new research focuses on maximizing the light extraction efficiency of LEDs and lowering cost through simpler materials.
Researchers at the Rensselaer Polytechnic Institute (RPI) Smart Lighting Engineering Research Center (ERC) have integrated a power transistor in gallium-nitride (GaN) layers along with an LED structure. An RPI doctoral student has also published research on a novel method that could improve the light extraction efficiency of LEDs. Researchers at the University of Washington hope to reduce the cost of slid-state lighting (SSL) products via a transition from phosphors based on rare-earth elements to electroluminescent silicon particles derived from sand.
Integrating circuit elements
The RPI research is focused on adding functionality to LED chips that can simplify the increasingly complex external electronics required to drive the LED. The laboratory project involved the monolithic integration of both a high-electron-mobility transistor (HEMT) and an LED on one chip. This simple first step of integration could provide a real benefit, eliminating the external MOSFET power transistor typically used to switch an LED on and off.
When asked whether the laboratory research would bring real value to the SSL space, T. Paul Chow, an engineering professor at RPI and the leader of the recent research, said, "Eliminating the MOSFET is the first step. We can add the gate driver circuitry, and then more integration to realize a power converter." Chow also said a single HEMT could control multiple LEDs on one chip.