Serge L. Rudaz

III–V Nitride semiconductors for high-performance blue and green light-emitting devices

Most of the rapid developments in (AlIn)GaN alloy system technology have occurred within the past few years, and the technology is still moving at a fast pace. New performance records for light-emitting diodes and laser diodes are constantly being reported. This article highlights the progression of the development of the (AlIn)GaN alloy system and describes the fabrication and performance of some of the light-emitting devices that have been produced to date.

NMR studies of simple molecules on metal surfaces.

In recent years, improvements in the sensitivity of nuclear magnetic resonance have made it possible to detect progressively smaller numbers of nuclei. Experiments and studies previously thought to be impractical can now be undertaken, for example, the study of phenomena at surfaces. Nuclear magnetic resonance has been applied to study simple molecules (carbon monoxide, acetylene, and ethylene) adsorbed on metal surfaces (ruthenium, rhodium, palladium, osmium, iridium, and platinum). The metals, in the form of clusters 10 to 50 angstroms in diameter, supported on alumina, are typical of real catalysts. The experiments provide information about the bonding of the molecules to the metal, the structures the molecules assume after adsorption, the motion of molecules on the surface, the breakup of molecules induced by heating, and the products of such breakup.

High-performance AlGaInP light-emitting diodes

A new class of LEDs based on the AlGaInP material system first became commercially available in the early 1990s. These devices benefit from a direct bandgap from the red to the yellow-green portion of the spectrum. The high efficiencies possible in AlGaInP across this spectrum have enabled new applications for LEDs including automotive lighting, outdoor variable message signs, outdoor large screen video displays, and traffic signal lights. A review of high-brightness AlGaInP LED technology will be presented.