The research activities include GaN-based films growth, rear-earth elements doping, film quality characterizations, photoluminescent emission measuring and electroluminescent device fabrication. A modified AIXTRON MOCVD system (AIX200) is employed for film growth.

GaN films were grown on different substrates, such as c-sapphire, GaN/sapphire and Si. Growth temperature was controlled in a range of 1000 to 1030˚C. Growth pressure was set for 50mbar. TMGa and NH₃ were used as precursors for Ga and N sources, respectively. High quality crystalline GaN films were obtained. The following figure shows the XRD spectrum of as grown GaN film on c-sapphire substrate.

Rare earth element (Eu) doping were carried out during GaN films growth. Eu(thd)₃ was used as RE precursor. Bright red emission from Eu-doped GaN films was detected at room temperature by using a He-Cd 325nm laser to pump the sample. The Photoluminescence spectrum and a picture of the red emitting sample are shown here.

More RE elements (Er, Ce, Tm) doping is conducted and a p-i-n structure growth is also on the way.

(Ming)