Characteristics of a-Plane Green Light-Emitting Diode Grown on r-Plane Sapphire

Abstract

Abstract-In this work, we have successfully grown a-plane green light-emitting diodes (LEDs) on r-plane sapphire and investigated the device characteristics of a-plane green LEDs. The apparent emission polarization anisotropy was observed and the polarization degree was as high as 67.4%. In addition, the electroluminescence (EL) spectra first revealed a wavelength blue-shift with increasing drive current to 20 mA, which could be attributed to the band-filling effect, and then the EL peak become constant. The current-voltage curve showed the forward voltage of a-plane LED grown on r-plane sapphire substrate was 3.43 V and the differential series resistance was measured to be about 24 as 20-mA injected current. Furthermore, the output power was 240 W at 100-mA drive current.

Improved device performance in nonpolar a ‐plane GaN LEDs using a Ni/Al/Ni/Au n‐type ohmic contact

“…However, the device performance of these a ‐plane GaN LEDs is still poor due to the immaturity in both the growth and fabrication methods, as compared to conventional c ‐plane ones 3, 4, by which high threading dislocations, basal‐plane stacking faults and high series resistance become critical issues that need to be overcome. Nowadays, much effort has been made to solve these problems 5, 6; however, most of the reports focused on the high‐quality a ‐plane GaN growth, not much on the device and/or process optimization for current injections in this area. In fact, since the a ‐plane GaN has a different Ga‐ and N‐atom surface condition, it is of particular importance to develop a unique metal scheme suitable for such a surface condition.…”

Investigation of the Electroluminescence Mechanism of GaN-Based Blue and Green Light-Emitting Diodes with Junction Temperature Range of 120–373 K

“…It was observed that the emission peak energy has a linear relationship with the current and increases with increasing current. This relationship is attributed to the electric field formed by the increased carrier concentration that decreases the impact of the quantum-confined Stark effect (QCSE) [26,34] and the energy band filling effect [35,36]. The excitons' lifetime decreased in the high-temperature range, and therefore, as the current increased the excitons could not occupy the lower energy state prior to the recombination, leading to the blue shift of the emission peak [27].…”

Characteristics of indium incorporation in InGaN/GaN multiple quantum wells grown on a-plane and c-plane GaN

“…Meanwhile, green light (around 510 nm) first emits from the a-plane LEDs at low current injection (0.15 mA) and then blue light emerges as the injection current is increased from 5 to 50 mA. This can be attributed primarily to the band-filling effect of the defect related stronger indium localized state 13,20 with smaller dimensions and lower density, resulting in a deeper and narrower indium localized band structure in a-plane MQWs. Figures 4(a) and 4(b) show the atomic structures of the a-plane and c-plane GaN surfaces, respectively.…”