InGaAs quantum well diode lasers with regrown Al containing layers for application to current confinement structures

Vertical cavity surface emitting lasers (VCSELs) with ultralow threshold and high efficiency have been fabricated using oxide apertures formed by selective oxidation of AlAs. Recent studies by Cheng et al. (1996) have shown that the expected reduction in threshold with aperture size is not achieved due to current spreading and lateral carrier diffusion even for rather large apertures (>5 /spl mu/m). To minimize these losses, we are exploring the use of a buried active region in VCSELs. To achieve the desired confinement in a buried heterostructure (BH) VCSEL, it is necessary to use selective area growth or regrowth of active region. Selective area epitaxy (SAE) also allows one to vary the cavity design locally by varying the masking pattern to achieve WDM arrays. SAE or regrowth must be done with tight regrowth process control to achieve very small thickness changes during the process and a low electrical and optical loss after regrowth. In this paper, we describe the impact of multiple step regrowth of device structures with Al containing layers on the luminescence and lasing characteristics of the resultant devices.