Optimization of MOCVD growth using tertiarybutylarsine and tertiarybutylphosphine for the realization of 1.55 micrometer low threshold current laser

This dissertation leads to a greater understanding of the parameters required to achieve low threshold current lasers using Metal Organic Chemical Vapor Deposition (MOCVD). First the bulk growth conditions for the safer sources Tertiarybutylarsine (TBA) and Tertiarybutylphosphine (TBP) will be highlighted. Then QW interfaces will be shown to have a dependence on growth purges as short as 0.5 seconds. Based on optimized interfaces, 1.55 $mu$m quantum well lasers grown with these sources resulted in record low threshold current densities of 220 A/cm$sp2$ for SQW unstrained, 180 A/cm$sp2$ for 2QW tensile strained, and 240 A/cm$sp2$ for 4QW compressively strained.;In order to achieve low threshold current, single mode devices with these active regions, ridge and buried lasers were investigated. For buried lasers, non-planar selective regrowth was necessary to create blocking layers along the edges of the active region. This type of planarized blocking structure requires precise control of both the etching and the regrowth conditions. The optimum conditions for non planar regrowth with MOCVD will be discussed. To optimize the blocking layer performance, the leakage through an n-p-n-p blocking layer will be analyzed and the leakage through the n-p-n transistor will be shown to be the limiting high current leakage path. The gain of this n-p-n transistor which is determined by the doping level, thickness, and positioning of the p-layer is shown to be the critical leakage parameter. Finally the realization of low threshold current 1.55 $mu$m buried lasers will be shown. Buried 2QW lasers exhibited uncoated thresholds less than 10 mA, low internal losses of 7 cm$sp{-1},$ efficiencies around 50%, and low leakage at currents below 200 mA.