We are reporting the first successful fabrication of 850-nm buried tunnel junction (BTJ) VCSELs. Multiple parameters were considered for the design. First, n-type dopants other than silicon had to be considered for an abrupt junction. Second, proper layer thickness had to be chosen. Finally, compatibility with regrowth and processing had to be ensured. In this paper the successful fabrication and performance of 850-nm BTJ VCSELs with tunnel junctions comprised of GaAs and AlGaAs materials is demonstrated. Key achieved parameters include a significant improvement in the slope efficiency from approximately 0.45 W/A in an oxide-aperture VCSEL to over 0.6 W/A.
InAs quantum dots embedded in InGaAs quantum well (DWELL) structures grown by metal-organic chemical-vapor
deposition on nano-patterned GaAs pyramids and planar GaAs (001) substrate are comparatively investigated.
Photoluminescence (PL), PL excitation, and time-resolved PL measurements demonstrate that the DWELL grown on the
GaAs pyramids has a broad QW PL band (FWHM ~ 90 meV) and a better QD emission efficiency than the DWELL
structure grown on the planar GaAs (001) substrate. These properties are attributed to the InGaAs QW with distributed
thickness profile on the faceted GaAs pyramid, which introduces tapered energy band structure and assists the carrier
capture into the QDs. This research provides useful data for further improving the performance of DWELL structures for
In this paper, we describe the results of using strain-compensation (SC) for closely-stacked InAs/GaAs quantum dot (QD) structures. The effects of the (In)GaP SC layers has been investigated using several methods. High-resolution x-ray diffractometry (XRD) quantifies the values of experimental strain reduction compared to calculations. Atomic force microscopy (AFM) indicates that the SC layer improves both QD uniformity and reduces defect density. Furthermore, increase in photoluminescence (PL) intensity has been observed from compensated structure. The use of Indium-flushing to dissolve large defect islands prevent further defect propagation in stacked QD active region. Room-temperature ground-state lasing at emission wavelengths of 1227-1249 nm have been realized with threshold current densities of 208-550 A/cm<sup>2</sup> for 15-20 nm spacing structures.