Lattice-matched Al/sub 0.95/Ga/sub 0.05/AsSb oxide for current confinement in InP-based long wavelength VCSELs

InP-based active region is the material-of-choice for long wavelength VCSELs. In order to develop low threshold VCSELs, it is essential to have lateral current- and optical-confining apertures. The use of AlAs oxide-defined apertures has resulted in reduced optical loss of short wavelength VCSELs grown lattice-matched to GaAs. On the other hand, the InP lattice-matched analogue, namely AlInAs (TA,), is not an ideal candidate for oxide apertures because of its slow oxidation rate and high oxidation temperature. Though the efforts to increase the oxidation rate by using strained (T/sub As//AlAs) and strain-compensated (AlAs/InAs) superlattices have shown improvement in the oxidation rate and current confinement, it would be desirable to have a lattice-matched confinement layer which can be oxidized at much lower temperatures to increase the process reliability and yield. In this paper, we have studied the InP lattice-matched Al/sub 0.95/Ga/sub 0.05/AsSb (Q/sub Sb/) oxide layer for current confinement.