Abstract
We propose a graded indium composition p-type InGaN (p-InGaN) conduction layer to replace the p-type AlGaN electron blocking layer and a p-GaN layer in order to enhance the light output power of a GaN-based green light-emitting diode (LED). The indium composition of the p-InGaN layer decreased from 10.4% to 0% along the growth direction. The light intensity of the LED with a graded indium composition p-InGaN layer is 13.7% higher than that of conventional LEDs according to the experimental result. The calculated data further confirmed that the graded indium composition p-InGaN layer can effectively improve the light power of green LEDs. According to the simulation, the increase in light output power of green LEDs with a graded indium composition p-InGaN layer was mainly attributed to the enhancement of hole injection and the improvement of the radiative recombination rate.
Highlights
GaN-based light-emitting diodes (LEDs) have attracted considerable attention and have been seen as a promising replacement for conventional light sources in the last few decades [1,2]
A large polarization field [14,15,16] and poor crystal quality [17,18] are the main reasons for the low internal quantum efficiency (IQE) of green LEDs with a high indium composition
The poor hole injection plays an important role in the low quantum efficiency of GaN-based LEDs
Summary
GaN-based light-emitting diodes (LEDs) have attracted considerable attention and have been seen as a promising replacement for conventional light sources in the last few decades [1,2]. The internal quantum efficiency (IQE) of GaN-based green LEDs is still lower than that of blue LEDs, which is called the “Green Gap” [13]. The poor hole injection plays an important role in the low quantum efficiency of GaN-based LEDs. Many researchers have proposed various methods to solve this problem based on band engineering of the electron blocking layer (EBL). Kim et al employed an active-layer-friendly lattice-matched InAlN EBL to improve the quantum efficiency of green LEDs [19]. A recently proposed method to improve the properties of p-type GaN is polarization doping [27].
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