Efficiency studies on semipolar GaInN-GaN quantum well structures

Abstract

In order to clarify the reasons for the fairly poor electroluminescence (EL) performance of semipolar LED structures grown on patterned sapphire wafers, we have analyzed both, pure photoluminescence (PL) test structures without doping only containing 5 GaInN quantum wells and full EL test structures, all emitting at a wavelength of about 510 nm. Evaluating the PL intensity over a wide range of temperatures and excitation powers, we conclude that such quantum wells possess a fairly large internal quantum efficiency of about 20%. However, on EL test structures containing nominally the same quantum wells, we obtained an optical output power of only about 150μW at an applied current of 20 mA. This may be due partly to some thermal destruction of the quantum wells by the overgrowth with p‐GaN. Even more important seems to be the not yet finally optimized p‐doping of these structures.

Recent progress in InGaN-based photodetectors for visible light communication

“…This electric field causes the energy band and conduction band of the quantum well to tilt, thereby shifting the wave functions of electrons and holes, increasing the carrier transit time, and reducing the quantum efficiency. This is called the quantum confined Stark effect (QCSE) 50 which is an important factor that restricts the bandwidth and responsivity of the PDs.…”

Начальные стадии роста полуполярного AlN на наноструктурированной Si(100) подложке

“…Однако нитриды алюминия и галлия являются пьезоэлектрическими материалами и использование (0001) плоскости в оптоэлектронных приборах на их основе приводит к проявлению эффекта Штарка. Замена полярных слоев полуполярными или неполярными для снижения негативного влияния этого эффекта становится привлекательной задачей для устройств оптоэлектроники [3]. Однако выращивание слоев AlN на Si является сложной задачей из-за большого рассогласования параметров решеток.…”

Efficient Semipolar (11–22) 550 nm Yellow/Green InGaN Light-Emitting Diodes on Low Defect Density (11–22) GaN/Sapphire Templates

“…Nevertheless, semipolar GaN layers grown on foreign substrates suffer from high densities of basal stacking faults (BSFs) and threading dislocations (TDs), leading to low efficiency devices . Efforts have been focused on defect management to improve the crystal quality of semipolar GaN materials grown on foreign ones to improve the device performance. − To date, a few papers have been reported on semipolar LEDs with long emission wavelength on sapphire substrates, and those LEDs still exhibit low output power and reduced external quantum efficiency (EQE). − …”