Monday, January 28, 2013

Graphene transparent electrode for enhanced optical power and thermal stability in GaN light-emitting diodes

Doo-Hyeb Youn, Young-Jun Yu, HongKyw Choi, Suck-Hwan Kim, Sung-Yool Choi and Choon-Gi Choi



We report an improvement of the optical power and thermal stability of GaN LEDs using a chemically doped graphene transparent conducting layer (TCL) and a low-resistance contact structure. In order to obtain low contact resistance between the TCL and p-GaN surface, a patterned graphene TCL with Cr/Au electrodes is suggested. A bi-layer patterning method of a graphene TCL was utilized to prevent the graphene from peeling off the p-GaN surface. To improve the work function and the sheet resistance of graphene, CVD (chemical vapor deposition) graphene was doped by a chemical treatment using a HNO 3 solution. The effect of the contact resistance on the power degradation of LEDs at a high injection current level was investigated. In addition, the enhancement of the optical power via an increase in the current spreading and a decrease in the potential barrier of the graphene TCL was investigated.



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