| High band gap III-V semiconductor alloys, GaAs{dollar}sb{lcub}rm 1-x{rcub}{dollar}P{dollar}sb{lcub}rm x{rcub}{dollar}, Ga{dollar}sb{lcub}rm x{rcub}{dollar}In{dollar}sb{lcub}rm 1-x{rcub}{dollar}P, and (Al{dollar}sb{lcub}rm x{rcub}{dollar}Ga{dollar}sb{lcub}rm 1-x{rcub}{dollar}){dollar}sb{lcub}rm y{rcub}{dollar}In{dollar}sb{lcub}rm 1-y{rcub}{dollar}P, have been successfully grown on GaAs substrates using atmospheric pressure organometallic vapor-phase epitaxy (OMVPE). Trimethylgallium (TMGa), trimethylindium (TMIn), and trimethylaluminum (TMAI), were used as group III source materials, and arsine (AsH{dollar}sb3{dollar}), phosphine (PH{dollar}sb3{dollar}), and tertiarybutylphosphine (TBP) were used as group V source materials.; For the growth of GaAs{dollar}sb{lcub}rm 1-x{rcub}{dollar}P{dollar}sb{lcub}rm x{rcub}{dollar}, strained layer superlattices (SLSs) were used to reduce misfit dislocation density. The grown structure consisted of a 2-{dollar}mu{dollar}m P compositionally graded layer, a GaAs{dollar}sb{lcub}rm 1-y'{rcub}{dollar}P{dollar}sb{lcub}rm y'{rcub}{dollar}/GaAs{dollar}sb{lcub}rm 1-y{rcub}{dollar}P{dollar}sb{lcub}rm y{rcub}{dollar} SLS, and a 1-{dollar}mu{dollar}m GaAs{dollar}sb{lcub}0.6{rcub}{dollar}P{dollar}sb{lcub}0.4{rcub}{dollar} layer. It was found that linear grading gave the lowest dislocation density among the three grading layers investigated: sublinear, hyperlinear, and linear. A novel method, called "overshoot," was developed to prevent the release of residual strain in the 2-{dollar}mu{dollar}m linearly graded layer. Using the overshoot method and SLSs, GaAs{dollar}sb{lcub}0.6{rcub}{dollar}P{dollar}sb{lcub}0.4{rcub}{dollar} with good surface morphology, strong visible photoluminescence(PL) intensity, and a dislocation density of 6.5 {dollar}times{dollar} 10{dollar}sp5{dollar} cm{dollar}sp{lcub}-2{rcub}{dollar} has been obtained.; For growth of GaInP, the effect of growth rate on the properties of the layers was investigated. It was observed that surface morphology degraded, the band gap at 300K decreased by 40meV, and the degree of ordering and size of ordered domains increased when the growth rate was changed from 12 to 4.1 {dollar}mu{dollar}m/hr. At high growth rates ({dollar}sim{dollar}12{dollar}mu{dollar}m/hr), the 300-K band gap of epilayer had the same values as the layers grown by LPE and was independent of the V/III ratio. The epilayers grown at a rate of 12{dollar}mu{dollar}m/hr and a V/III ratio of 148 had PL halfwidths of 35 and 7.2meV at 300K and 10K, respectively, the best reported results to date. A mechanism for the growth rate effect on the properties of OMVPE-grown GaInP is discussed.; For the growth of AlGaInP, either PH{dollar}sb3{dollar} or TBP was used as the group V source material, respectively. For layers grown using trimethylalkyls and PH{dollar}sb3{dollar}, excellent surface morphologies were obtained over the entire Al composition range. The 300-K band gap varied with x as 1.9 + 0.6x, consistent with calculated and previous results. The experimental results showed that the minority-carrier lifetime was constant when Al concentration was changed. For layers grown using trimethylalkyls and TBP, the P vapor pressure required was less than that using PH{dollar}sb3{dollar} to obtain good surface morphologies. No parasitic reactions were observed between TBP and the trimethylalkyls. However, the PL peak energy for layers grown using TBP did not follow the relation 1.9 + 0.6x. This was explained by a deep donor level, induced by an impurity from the TBP, bound to the X conduction band minimum. It is concluded that TBP is a suitable material to replace PH{dollar}sb3{dollar} for OMVPE growth of Al-containing compounds. |
