Light-extraction efficiency and forward voltage in GaN-based light-emitting diodes with different patterns of V-shaped pits

Abstract

We present a new method of making a textured V-pit surface for improving the light extraction efficiency in GaNbased light-emitting diodes and compare it with the usual low-temperature method for p-GaN V-pits. Three types of GaNbased light-emitting diodes (LEDs) with surface V-pits in different densities and regions were grown by metal-organic chemical vapor deposition. We achieved the highest output power and lowest forward voltage values with the p-InGaN V-pit LED. The V-pits enhanced the light output power values by 1.45 times the values of the conventional LED owing to an enhancement of the light scattering probability and an effective reduction of Mg-acceptor activation energy. Moreover, this new technique effectively solved the higher forward voltage problem of the usual V-pit LED.

Strong Enhancement in Light Output of GaN-Based LEDs With Graded-Refractive-Index ITO Deposited on Textured V-Shaped Pits

“…The V-shaped textured surface is made by doping a certain amount of trimethyindium (TMIn) flow. This is a new approach for forming the V-shaped pits [5], and is used in devices B to D. The In-doped p-GaN layer will generate the pure or mixed screw thread dislocations and shape the V-pits. The growth temperature of the V-pits is 920°C, which is the same as LED A.…”

“…Nowadays, the naturally textured V-shaped pits (V-pits) which were grown on the p-GaN surface have remarkably enhanced light extraction of LEDs [5], [6]. The uniformity of the V-pits structure is good in wafers.…”