1State Key Laboratory of Mechanical Transmission, College of Physics, Chongqing University, Chongqing 40044 2College of Software, Chongqing College of Electronic Engineering, Chongqing 401331 3College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047 4Chongqing Engineering Research Center of Graphene Film Manufacturing, Chongqing 401331
Abstract：The thermal-electrical characteristic of a GaN light-emitting diode (LED) with the hybrid transparent conductive layers (TCLs) of graphene (Gr) and NiO$_x$ is investigated by a finite element method. It is indicated that the LED with the compound TCL of 3-layer Gr and 1 nm NiO$_x$ has the best thermal-electrical performance from the view point of the maximum temperature and the current density deviation of multiple quantum wells, and the maximum temperature occurs near the n-electrode rather than p-electrode. Furthermore, to depress the current crowding on the LED, the electrode pattern parameters including p- and n-electrode length, p-electrode buried depth and the distance of n-electrode to active area are optimized. It is found that either increasing p- or n-electrode length and buried depth or decreasing the distance of n-electrode from the active area will decrease the temperature of the LED, while the increase of the n-electrode length has more prominent effect. Typically, when the n-electrode length increases to 0.8 times of the chip size, the temperature of the GaN LED with the 1 nm NiO$_x$/3-layer-Gr hybrid TCLs could drop about 7 K and the current density uniformity could increase by 23.8%, compared to 0.4 times of the chip size. This new finding will be beneficial for improvement of the thermal-electrical performance of LEDs with various conductive TCLs such as NiO$_x$/Gr or ITO/Gr as current spreading layers.
2016, Vol. 33 
