High power and high efficiency nonpolar m-plane (1100) nitride light emitting diodes (LEDs) have been fabricated on low extended defect bulk m-plane GaN substrates. The LEDs were grown by metal organic chemical vapor deposition (MOCVD) using conditions similar to that of c-plane device growth. The output power and external quantum efficiency (EQE) of the packaged 300 ×300 µm2 was 23.7 mW and 38.9%, respectively, at 20 mA. The peak wavelength was 407 nm and <1 nm redshift was observed with change in drive current from 1–20 mA. The EQE shows a minimal drop off at higher currents.

Improved nonpolar m ‐plane $\bar 1$ light emitting diodes (LEDs) with a thick InGaN multi‐quantum‐well (MQW) structure have been fabricated on low extended defect bulk m ‐plane GaN substrates using metal organic chemical vapor deposition (MOCVD). The peak wavelength of the electroluminescence emission from the packaged LEDs was 402 nm, which is in the blue‐violet region. The output power and EQE were 28 mW and 45.4%, respectively, at a pulsed driving current of 20 mA. With increasing current, the output power increased linearly, and fairly flat EQE was observed with increasing drive current. At 200 mA, the power and EQE were 250 mW and 41%, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A yellow-emitting phosphor, La1−xCex3+Sr2AlO5, is reported that displays a peak in the excitation at 450nm and a peak in the emission at 556nm. When this phosphor is pumped by a blue InGaN light-emitting diode (λmax=450nm) we obtain white light with color rendering index (Ra) between 81 and 85 and color temperatures between 4200 and 5500K, suggesting that this material is competitive as a blue-pumped yellow phosphors.

We demonstrate high power yellow InGaN single-quantum-well light-emitting diodes (LEDs) with a peak emission wavelength of 562.7nm grown on low extended defect density semipolar (112¯2) bulk GaN substrates by metal organic chemical vapor deposition. The output power and external quantum efficiency at drive currents of 20 and 200mA under pulsed operation (10% duty cycle) were 5.9mW, 13.4% and 29.2mW, 6.4%, respectively. It was observed that the temperature dependence of the output power of InGaN LEDs was significantly smaller than that of AlInGaP LEDs.

Cerium-doped lanthanum strontium aluminum oxide LaSr 2 AlO 5 :Ce 3+ has recently been identified by us as a viable yellow phosphor that in conjunction with a blue-emitting diode can be used in solid-state white lighting sources. In this study, we present the energy level structure relevant to the luminescence process within LaSr 2 AlO 5 :Ce 3+ , based on crystal structure determination by powder X-ray diffraction and the peak deconvolution of excitation and emission spectra. We also establish the versatility of the phosphor host LaSr 2 AlO 5 by examining isovalent substitutions of all three cation types in the structure; Gd or Tb for La, Ca or Ba for Sr, and B or Ga for Al. All the above cation substitutions/solid solution are achieved to the full extent except when Ca (for Sr) or B (for Al) are chosen as substituent. Optical properties of the prepared Ce 3+ phosphors are found to depend on the rare-earth metal-oxygen distances and the lattice ionicity. Among the compounds studied here, excitation maxima range between 435 and 453 nm and emission maxima between 552 and 577 nm, which are promising for delicate color control in InGaN-based blue-pumped, yellow-emitting phosphors for solid-state white lighting. Prototype light-emitting diodes have been fabricated by formulating various phosphor compositions obtained in this study, and their electroluminescence properties are presented.