Low-resistance InGa(Al)As Tunnel Junctions for Long Wavelength Vertical-cavity Surface-emitting Lasers

Abstract

A new method is proposed for a significant reduction of series resistance and device heating in long wavelength vertical-cavity surface-emitting lasers (VCSELs) based on InP. Our technique involves a twofold epitaxial growth with a buried low-resistance (3×10^-6 Ωcm²) tunnel junction. The substitution of high-resistive p-type confining layers by low-resistive n-type material results in total resistances smaller 100 Ω even for the case of non-conducting dielectric mirrors. With the application of buried tunnel junctions in a VCSEL-structure, we could demonstrate small electrical series resistance (U < 1 V at 3 kAcm^-2) and effective current confinement simultaneously. Furthermore, because of the laterally varying cavity length, an effective lateral waveguiding effect occurs.