Nitrogen-doped ZnSe grown by low-pressure metalorganic chemical vapor deposition with alternate growth and active nitrogen doping

Active nitrogen generated by plasma discharge has been used as a nitrogen dopant source in low-pressure metalorganic chemical vapor deposition (MOCVD) with dimethylzinc or diethylzinc and H2Se as precursors. Growth and doping were carried out alternately to avoid the decomposition of the precursors in the gas phase by active nitrogen and to collect information on the growth surface. Growth per cycle was about one monolayer and growth repetition was 7200 cycles. The electrical and luminescence properties of N-doped ZnSeGaAs(100) layers grown under various growth conditions are investigated. Judging from the luminescence spectra, nitrogen is incorporated more effectively with decreasing the VIII ratio, suggesting the stoichiometry of the growth surface correlates with the ratio. The N-doped ZnSe layers grown under low VIII ratios, however, show highly n-type conductivity. From the different effect between active nitrogen and NH3 as nitrogen dopant sources on the electrical properties, it is suggested that alkyl radicals existing at the growth front play an important role in producing donor species and that dopant sources, which provide reaction paths for the alkyl radicals to form inert hydrocarbons, are necessary to prepare p-type ZnSe layers.