The fabrication of GaN-based light emitting diodes (LEDs)

In this paper, we report on the fabrication of blue GaN based light emitting diodes (LEDs), and then on coating procedures to obtain white LED lamps from blue LED chips. Firstly, the multi-layers of nanometer thickness GaN are grown on quarters of 2-inch diameter (0001)-orientation (c-plane) sapphire substrates by using metal organic chemical vapor deposition (MOCVD) for a subsequent realization of the LED structures. Then, the blue GaN based LEDs are fabricated by using several standard microfabrication techniques, including mesa etching, metal deposition, lift-off and annealing. The luminous intensity of the fabricated blue LED chips, measured with a current of 20 mA, is approximately 80 millicandela (mcd). Afterward, a solution of phosphor (Y3Al5O12 : Ce): epoxy is prepared to coat the blue LED chips, thus obtaining the white LED lamps. After the coating procedure, the power of the fabricated white LED lamps is about 40 lmW-1 at 20mA current. All the obtained results have proved the success of the GaN-based LED fabrication and white LED lamps produced. © 2010 Vietnam Academy of Science & Technology.