Characterization of the InGaN/GaN Multi-Quantum-Wells Light-Emitting Diode Grown on Patterned Sapphire Substrate with Wide Electroluminescence Spectrum

Abstract

We report the characterization of the InGaN/GaN multi-quantum-well (MQW) light-emitting diode (LED) grown on a patterned sapphire substrate by metal organic chemical vapor deposition (MOCVD) using the selective area growth (SAG) method. The SAG patterns were designed to be circular and their diameters were 700 and 200 m. After the growth, the InGaN/GaN MQW LED of 200 m diameter had various crystal facets and a shape similar to volcanic craters, which were not observed in the 700-m-diameter sample. We obtained an active layer with compositional nonuniformity and superior optical properties. We found wide electroluminescence (EL) spectral peaks near 470, 570, and 600 nm. The distribution of the EL spectrum of the sample was similar to that of a conventional phosphor-converted white LED.

Enhance Light Emitting Diode Light Extraction Efficiency by an Optimized Spherical Cap-Shaped Patterned Sapphire Substrate

“…1) Accordingly, GaN-based semiconductors as the most promising materials for fabrication of blue and white LEDs since p-GaN was successfully doped by Akasaki have recently attracted intensive interests. [2][3][4][5] Though LEDs' luminous efficiency has been far beyond the level of filament lamp, to cope with the market demand for high power lighting and make full use of LEDs' superiorities, i.e., energy conservation and high reliability, higher luminous efficiency for LEDs is inevitably demanded. In general, luminous efficiency depends on both internal and external quantum efficiency.…”

Characteristics of InGaN‐Based Light‐Emitting Diodes on Patterned Sapphire Substrates with Various Pattern Heights

“…The critical angle is roughly 24.6 • , which indicates that less light is extracted from the surface [4]. For this reason, several alternative approaches have been introduced to improve light extraction efficiency, including approaches that make use of p-GaN roughness [5], indium tin oxide (ITO) mesh [6], a laser liftoff process [7], and a patterned sapphire substrate (PSS) [8][9][10][11]. In particular, use of a PSS not only enhances the light extraction rate but also decreases threading dislocation defects because the growth mechanism is similar to epitaxial lateral overgrowth (ELOG) [12].…”