Output power enhancement of GaN light emitting diodes with p-type ZnO hole injection layer

Abstract

We report an enhancement of the optical output power of GaN light emitting diodes (LEDs) by addition of a p-type ZnO layer located in close proximity to the active layer (ZnO/GaN LEDs). Arsenic (As)-doped p-ZnO was used as a hole-injecting layer to overcome the drop in external quantum efficiency of GaN LEDs at high drive currents—the so-called “efficiency droop.” The output power in ZnO/GaN LEDs was improved up to 40%. This result is useful for development of highly efficient GaN LEDs operating at high current densities that will play a critical role in replacement of incandescent lamps by high efficiency solid-state light bulbs.

Electronic transport and Schottky barrier heights of Pt/n-type GaN Schottky diodes in the extrinsic region

“…[1][2][3][4][5] Other devices that have been demonstrated so far include ultraviolet Schottky barrier photodetectors, solar-blind Schottky photodiodes, metal-semiconductor ͑MS͒ field effect transistors, and high electron mobility transistors. 6-10 MS contact is one of the most widely used rectifying contacts in the electronics industry.…”

Effect of a p-type ZnO insertion layer on the external quantum efficiency of GaInN light-emitting diodes

“…5) Accordingly, many studies have been published showing an improved EQE when ZnO layers are utilized in GaInN LEDs. [5][6][7][8][9][10][11][12][13][14][15] The reason for the efficiency improvement caused by the inclusion of a ZnO layer has not yet been fully understood, although several hypotheses, such as better refractive index matching than conventional metal oxide electrodes, 10,12) better current spreading than ITO, 13) better transparency than ITO, 9,15) and improved hole injection efficiency, 14) have been published. In this study, we investigate an LED structure with a p-type ZnO layer between the ITO electrode and the p-type GaN layer.…”

Properties of phosphorus-doped zinc oxide films grown by pulsed laser deposition

“…Several research groups have reported success in achieving p-type conductivity in N-, P-, and As-doped ZnO thin films. [10][11][12][13] Among group V elements, phosphorus is one of the promising candidates for p-type dopants. Recently, Hwang et al 14 reported realization of p-type conductivity in P-doped ZnO films by adjusting the pressure of rf magnetron sputtering.…”