Nanorod LED Arrays

Abstract

Wide bandgap GaN-based light emitting diodes (LEDs) have been intensively developed and revolutionized the solid-state lighting market in the past 10 years due to their ability to emit light ranging from ultraviolet to the short-wavelength part over the visible spectrum. However, there are some difficulties that limit the performance of GaN-based LEDs. The low light-extraction efficiency and straininduced quantum-confined Stark effect (QCSE) are the bottlenecks for high-power LEDs. For a GaN-based LED epi-structure, the lattice mismatch between InGaN and GaN results in strain and induces piezoelectric field. The field leads to the tilt of energy band structure and thus the separation of carriers in the active region, which decreases internal quantum efficiency (IQE) and causes wavelength shift of light emission. Great efforts are needed to overcome these obstacles in order to further improve the performance of LEDs.Low dimensional structures such as nanorods and nanowires have become prominent in recent years. With a diameter in nanoscale, the diode arrays may have advantages of increased surface to volume ratio due to sidewall etching and strain relaxation due to the vacant spaces among the rod array. Most researches on nanorod structure are restricted at material characterization. The process to