GaN/AlGaN Nanocolumn Ultraviolet Light-Emitting Diode Using Double-Layer Graphene as Substrate and Transparent Electrode

Abstract

The many outstanding properties of graphene have impressed and intrigued scientists for the last few decades. Its transparency to light of all wavelengths combined with a low sheet resistance makes it a promising electrode material for novel optoelectronics. So far, no one has utilized graphene as both the substrate and transparent electrode of a functional optoelectronic device. Here, we demonstrate the use of double-layer graphene as a growth substrate and transparent conductive electrode for an ultraviolet light-emitting diode in a flip-chip configuration, where GaN/AlGaN nanocolumns are grown as the light emitting structure using plasma-assisted molecular beam epitaxy. Although the sheet resistance is increased after nanocolumn growth compared with pristine double-layer graphene, our experiments show that the double-layer graphene functions adequately as an electrode. The GaN/AlGaN nanocolumns are found to exhibit a high crystal quality with no observable defects or stacking faults. Room temperature electroluminescence measurements show a GaN related near bandgap emission peak at 365 nm and no defect-related yellow emission.

AlGaN Nanowires for Ultraviolet Light-Emitting: Recent Progress, Challenges, and Prospects

“…AlGaN nanowire UV LEDs on the graphene-coated glass substrate have been demonstrated recently [98]. The UV light is emitted through the substrate.…”

“…Inset: EL spectra under different injection currents (from 0 mA to 1.75 mA). (b) EQE vs. the injection current[98].…”

High-brightness lasing at submicrometer enabled by droop-free fin light-emitting diodes (LEDs)

“…In planar LEDs, the IQE is shown to decrease by 30% as junction temperature increases from 23° to 177°C ( 22 – 24 ). As a result of these effects, measurements in nanoscale LEDs show a rollover of the IQE at injected currents as low as 0.3 to 4 mA ( 17 , 25 – 27 ).…”

Highly transparent and flexible Ag nanowire-embedded silk fibroin electrodes for biocompatible flexible and transparent heater

“…[1][2][3][4][5][6][7] During the past few decades, efforts to develop transparent electrode materials have mainly focused on transparent conductive oxide (TCO), metallic nanowires, conducting polymers, and carbon-based electrodes including carbon nanotubes, graphene, and graphene oxides. [8][9][10][11][12] Although several different kinds of transparent electrode materials have been suggested, Sn-doped In 2 O 3 (ITO) lm coated on a exible substrate or a glass substrate is most oen used in at panel displays, photovoltaics, touch screen panels, and sensors due to its high conductivity and transmittance. However, normal ITO lms on exible substrates cannot be applied to wearable electronics because ITO lm is brittle and typical exible substrates such as polyethylene (PET) and polyimide (PI) are not biocompatible with the human body.…”