Visible Vertical-Cavity Light Emitters

Abstract

This Thesis is concerned with resonant cavity light-emitting diodes (RCLEDs) and vertical-cavity surface-emitting lasers (VCSELs), which oscillate in the visible spectral range. It presents results obtained from studies of layer growth and device structures and the potential of RCLEDs and VCSELs as light sources for optical data communication systems at short wavelengths. In particular, it demonstrates the applicability of molecular beam epitaxy (MBE) for monolithic growth of RCLEDs and VCSELs complete with quantum wells, microcavities, and distributed Bragg reflectors, oriented perpendicular to the p-n junctions of the devices.

Low-cost communication systems based on standard polymethyl methacrylate (PMMA) plastic optical fibres (POFs) require reliable and inexpensive light sources that operate at 650 nm, where the fibre exhibits a local attenuation minimum. The RCLEDs of this Thesis are mainly intended for such applications.

The Thesis first presents a historical background and basic design concepts of vertical-cavity light emitters. Then theoretical considerations are given where appropriate to support the experimental work and to provide theoretical explanations for the observed phenomena. A detailed description of the fibre coupling efficiency, temperature behaviour, and the overall performance of closely optimised 650-nm RCLEDs is given. Finally, characteristics of preliminary 690-nm AlGaInP / GaAs VCSELs are discussed.