Nitrogen as carrier gas for the growth of ZnSe and ZnSe:N in plasma enhanced metalorganic vapor phase epitaxy

Abstract

For the precursor combination dimethylzinc-triethylamine and ditertiarybutylselenide the use of nitrogen carrier gas was investigated for the metalorganic vapor phase epitaxy (MOVPE) of ZnSe and ZnSe:N. The nitrogen doping was carried out with a separate nitrogen flow which was activated by a dc-plasma. In the photoluminescence spectra of undoped layers grown at 340°C with a VI/II ratio of 0.18 only excitonic emissions, separated into free and donor bound excitons, can be observed. The background carrier concentration was of the order of 1 x 10 16 cm -3 . The growth rate of epilayers grown in nitrogen is reduced by about 75% in comparison to the value obtained by using hydrogen as carrier gas. The doping can be regulated by the dopant flow and by the total pressure in the reactor. With increasing flow of plasma activated nitrogen and a reduced total pressure, the PL spectra showed broadened DAP emission without excitonic emissions. The electrical and optical properties obtained with nitrogen carrier gas are comparable with the results obtained with hydrogen carrier gas. So far, no p-type conductivity was measured. Therefore, the problem of compensation of p-type conductivity of ZnSe:N doped by dc-plasma enhanced N 2 was not solved by the use of N 2 carrier gas.