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

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 Ωcm 2 ) 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.