Effect of non-vacuum thermal annealing on high indium content InGaN films deposited by pulsed laser deposition

InGaN films with 33% and 60% indium contents were deposited by pulsed laser deposition (PLD) at a low growth temperature of 300 °C. The films were then annealed at 500-800 °C in the non-vacuum furnace for 15 min with an addition of N(2) atmosphere. X-ray diffraction results indicate that the indium contents in these two films were raised to 41% and 63%, respectively, after annealing in furnace. In(2)O(3) phase was formed on InGaN surface during the annealing process, which can be clearly observed by the measurements of auger electron spectroscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. Due to the obstruction of indium out-diffusion by forming In(2)O(3) on surface, it leads to the efficient increment in indium content of InGaN layer. In addition, the surface roughness was greatly improved by removing In(2)O(3) with the etching treatment in HCl solution. Micro-photoluminescence measurement was performed to analyze the emission property of InGaN layer. For the as-grown InGaN with 33% indium content, the emission wavelength was gradually shifted from 552 to 618 nm with increasing the annealing temperature to 800 °C. It reveals the InGaN films have high potential in optoelectronic applications

Effects of Growth Conditions on Structural Properties of ZnO Nanostructures on Sapphire Substrate by Metal–Organic Chemical Vapor Deposition

Abstract ZnO was grown on sapphire substrate by metal&#8211;organic chemical vapor deposition using the diethylzinc (DEZn) and oxygen (O2) as source chemicals at 500 &#176;C. Influences of the chamber pressure and O2/DEZn ratio on the ZnO structural properties were discussed. It was found that the chamber pressure has significant effects on the morphology of ZnO and could result in various structures of ZnO including pyramid-like, worm-like, and columnar grain. When the chamber pressure was kept at 10 Torr, the lowest full width at half-maximum of ZnO (002) of 175 arc second can be obtained. On the other hand, by lowering the DEZn flow rate, the crystal quality of ZnO can be improved. Under high DEZn flow rate, the ZnO nanowall-network structures were found to grow vertically on the sapphire substrate without using any metal catalysts. It suggests that higher DEZn flow rate promotes three-dimensional growth mode resulting in increased surface roughness. Therefore, some tip on the ZnO surface could act as nucleation site. In this work, the growth process of our ZnO nanowall networks is said to follow the self-catalyzed growth mechanism under high-DEZn flow rate.</p

P-side up AlGaInP-based light emitting diodeswith dot-patterned GaAs contact layers

High-brightness p-side up AlGaInP-based red light emitting diodes (LEDs) with dot-patterned GaAs contact layer and surface rough structure are presented in this article. Initial LED structure of p-GaP/AlGaInP/GaAs is epitaxially grown using metal organic chemical vapor deposition technique. Using novel twice transferring process, the p-GaP layer is remained at the top side as both the current spreading and-window layer. Dot patterned GaAs contact dots are formed between main structure and rear mirror to improve light reflection and current spreading. Moreover, the surface of p-GaP window is further textured by nano-sphere lithography technique for improving the light extraction. Significant improvement in output power is found for AlGaInP LEDs with GaAs contact dots and roughened p-GaP window as compared with those of LEDs with traditional n-side up and p-side up structures without roughened surfaces

P-side up AlGaInP-based light emitting diodeswith dot-patterned GaAs contact layers

High-brightness p-side up AlGaInP-based red light emitting diodes (LEDs) with dot-patterned GaAs contact layer and surface rough structure are presented in this article. Initial LED structure of p-GaP/AlGaInP/GaAs is epitaxially grown using metal organic chemical vapor deposition technique. Using novel twice transferring process, the p-GaP layer is remained at the top side as both the current spreading and-window layer. Dot patterned GaAs contact dots are formed between main structure and rear mirror to improve light reflection and current spreading. Moreover, the surface of p-GaP window is further textured by nano-sphere lithography technique for improving the light extraction. Significant improvement in output power is found for AlGaInP LEDs with GaAs contact dots and roughened p-GaP window as compared with those of LEDs with traditional n-side up and p-side up structures without roughened surfaces