Helium ion-implanted InGaAsP tunnel junction current blocking layers

We experimentally investigate and model He+-implanted InGaAsP tunnel junctions used for lateral current confinement in vertical-cavity surface-emitting lasers (VCSELs). Prior to implantation, a 56-μm-diameter tunnel junction exhibits a peak-to-valley ratio of 2.2 and a differential resistance of 27 Ω at -2 V. After implantation at a dose of 3.3x1013 cm-2, the current under reverse bias reduces by a factor of >107. Placing tunnel junctions close to the laser active region does not degrade the gain in the quantum wells. With He+-implanted tunnel junctions, mirrorless test VCSEL structures up to 50 μm diameter have uniform current distribution across the entire light-emitting apertures