Nanophotonic crystals on unpolished sapphire substrates for deep-UV light-emitting diodes

Enhancement of InGaN-Based Light Emitting Diodes Performance Grown on Cone-Shaped Pattern Sapphire Substrates

To enhance light extraction effciency, high-quality InGaN-based light emitting diodes (LED) was grown on cone-shaped patterned sapphire (CPSS) by using metal organic chemical vapor deposition (MOCVD). From the transmission electron microscopy (TEM) observation, the CPSS was confirmed to be an efficient way to reduce the threading dislocation density in the GaN epilayer. A sharp and high intensi...

Optical crosstalk analysis of micro-pixelated GaN-based light-emitting diodes on sapphire and Si substrates

With the aid of depth-resolved confocal microscopy, the optical crosstalk phenomenon in GaN-based micro-pixel light-emitting diodes (m-LEDs) on Si substrates are thoroughly investigated and compared with its counterpart on sapphire substrate. Noticeable optical crosstalk is invariably present in GaNon-sapphire devices as the thick transparent sapphires beneath the m-LEDs serve as optical wavegu...

Deep Ultraviolet AlGaInN-Based Light-Emitting Diodes on Si(111) and Sapphire

Ultraviolet light-emitting diodes (LEDs) with emission wavelength as short as 280 nm, grown by gas source molecular beam epitaxy with ammonia, are described. The typical multi-quantum well (MQW) structure LED consists of an AlN buffer layer deposited on Si(111) or sapphire, followed by a (Al)GaN buffer layer and two superlattice structures, nand p-type, with the MQW active region placed between...

Polycrystalline nitride semiconductor light-emitting diodes fabricated on quartz substrates

We demonstrate the feasibility of polycrystalline nitride semiconductor light-emitting diodes ~LEDs!. Here, polycrystalline LEDs were deposited on quartz substrates, incorporating a layer structure identical to that used for epitaxially grown LEDs. The deposition exhibits a tendency to produce c-oriented crystallites. Violet-blue ~430 nm! operation of a polycrystalline LED is demonstrated, with...

Light emitting diodes on silicon substrates: preliminary results