Chapter 1 Materials Issues in High-Brightness Light-Emitting Diodes
1997; Elsevier BV; Linguagem: Inglês
10.1016/s0080-8784(08)62402-3
ISSN0080-8784
Autores Tópico(s)ZnO doping and properties
ResumoPublisher Summary This chapter provides an overview of the basic issues involving the materials used for high-brightness light emitting diodes (LEDs). It lays the fundamental foundation for understanding the phenomena common to the materials discussed in this volume: Aluminium gallium indium phosphide (AlGaInP), for the spectral range of red through green, AlGaAs for high-efficiency red emitters, GaN for high-efficiency blue emitters, and GaInN for high-brightness blue and green emitters. This serves as introductory material for the more detailed chapters on these materials to follow. The already well-developed AlGaAs was the first to demonstrate extremely high efficiency (18%) red light emission in thick layers grown by liquid-phase epitaxy with no GaAs substrate to absorb the emitted photons. The much more difficult materials system AlGaInP has progressed remarkably, overcoming problems with oxygen contamination, p-type doping, ordering, and photon absorption in the substrate to produce materials with external quantum efficiencies equaling the best AlGaAs values, but at shorter wavelengths, giving considerably higher brightness in the red region of the spectrum. The highest performance orange and yellow LEDs have also been produced in this material.
Referência(s)