Physics and Technology of AlGaInN‐Based Laser Diode

Abstract

Laser diodes in the green, blue, violet, and ultraviolet spectral range are made from the binary compound semiconductors AlN, GaN, and InN and their ternary and quaternary mixed crystals. The fundamental properties of these AlGaInN laser diodes are introduced. These are double‐heterostructure laser diodes with separate confinement of electrons and holes in quantum wells and photons in an optical waveguide. A rate equation description of the static and temporal behaviors of optical output power and carrier density is introduced, as are substrates, crystal growth, and microtechnology processing methods. The routes toward longer wavelength in the green spectral region, shorter wavelength ultraviolet lasing, and higher power operation in broad‐area laser diodes are discussed. Several different realized laser designs, including vertical‐cavity surface‐emitting lasers (VCSELs), multi‐section short‐pulse lasers, and distributed Bragg reflector (DBR) lasers are introduced. The family of AlGaInN laser diodes constitutes a large variety of applications, as outlined at the end of the article.

Refractive Index of Heavily Germanium-Doped Gallium Nitride Measured by Spectral Reflectometry and Ellipsometry

“…Of all the semiconductor materials used for laser diodes, nitride semiconductors (AlGaInN) have established themselves as the most successful for efficient emission in the green–blue–ultraviolet range of the electromagnetic spectrum [ 1 ]. In this material system, increasing the amount of aluminium in the alloy is the preferred way to decrease the refractive index.…”