Effects of C incorporation on the luminescence properties of ZnSe grown by metalorganic chemical vapor deposition

Abstract The effects of C incorporation in heteroepitaxial ZnSe grown on GaAs by metalorganic chemical vapor deposition (MOCVD) with methylallylselenide (MASe), diethylselenide (DESe), and hydrogen selenide (H 2 Se) selenium precursors together with dimethylzinc (DMZn) are investigated. The effects of growth temperature and VI/II ratio are determined. In material grown at 480°C and above, all of the low temperature photoluminescence (PL) peaks are generally shifted several meV lower in energy than in material grown in the 300–425°C range. In particular, the light hole component of the neutral donor-bound exciton shifts down to around 2.792 eV, where it was incorrectly identified in previous work as an exciton bound to a complex involving C. Detailed PL and reflectance measurements give conclusive evidence for this interpretation. The peak shifts are attributed to increased thermal mismatch strain resulting from the higher growth temperature used with MASe and DESe. However, the VI/II ratio strongly affects the strain in samples grown at 500°C using DESe, suggesting that heavy C incorporation at the ZnSe/GaAs interface may stimulate the thermal relaxation. The mechanism might involve the formation of C-related microprecipitates near the interface, which then nucleate misfit dislocations. We conclude that C from the growth precursors does not produce any new PL peaks above 1.4 eV in MOCVD ZnSe. Moreover, the room temperature PL efficiency is not degraded in C-contaminated material, suggesting that C is not an important non-radiative recombination center in ZnSe. The incorporation of moderate C levels is found to have little effect on the optoelectronic properties of MOCVD ZnSe.