We propose to use lattice-matched AlInN/GaN to replace the Al(Ga)N/GaN material system for III-nitride Bragg reflectors, despite the poor material quality of AlInN reported until very recently. We report an improvement of AlInN material that allowed for successful fabrication of a microcavity light emitting diode, a distributed Bragg reflector with 99.4% reflectivity and microcavities with a quality factor over 800. These results establish state-of-the-art values for III-nitrides, and announce the future importance of AlInN in GaN-based optoelectronics.

No abstract

No abstract

Intersubband absorption measurements on two nominally undoped AlGaN/GaN-based high-electron-mobility transistors with different Al compositions in the barrier layer are presented. The first transistor with a barrier consisting of Al 0.6 Ga 0.4 N showed an absorption peak at 247 meV ͑1973 cm Ϫ1 ͒ with a full width at half maximum ͑FWHM͒ of 126 meV, while the second device utilizing an Al 0.8 Ga 0.2 N barrier had its peak at 306 meV ͑2447 cm Ϫ1 ͒ with a FWHM of 86 meV. Self-consistently computed potentials and intersubband transition energies showed good agreement with the experimental findings, and therefore confirmed previously published values for the internal piezoelectric field in such structures.During the last couple of years, the III nitrides have attracted a lot of attention as material for short wavelength diode lasers and also for high power electronic devices.

InGaN laser diodes were been grown by metalorganic vapor phase depositions on sapphire substrates. These lasers were processed as gain guided structures and showed lasing in pulsed mode operation with duty cycles up to 2% at a wavelength of 401 nm. We determined the activation energy of the carriers in the active region by temperature dependent electroluminescence measurements during LED operation. By this means we estimated the temperature evolution inside the quantum wells by recording the transients of the output intensity during a single pulse. To verify the correlation of light output power and heating of the active region we performed simulations of the heat distribution in laser diodes on a two‐dimensional mesh, which contained the laser structure including the substrate. With the help of these simulations we were able to reconstructed the temperature evolution within the active region in good agreement with the experiment and determined the heat generation to be the limiting factor of the lasers driving conditions. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

No abstract

No abstract

No abstract