Effects of hydrides of the group V elements on the growth of ZnSe by metalorganic chemical vapor deposition

The electrical and luminescence properties of ZnSe films grown on GaAs(100) at a substrate temperature of 350°C in an atmosphere of dilute NH3, PH3, or AsH3 have been studied. The N incorporation efficiency depends strongly on the [H2Se]/[dimethylzinc] molar ratio and thus on the stoichiometry of the films. The low-temperature electron mobility is enhanced markedly with slight NH3 addition, and a peak mobility of more than 10,000 cm2/V·s has been observed. No enhancement in mobility, however, has been observed with PH3 or AsH3 addition. The different effect on mobility of these dopants supports the assumption that a heterogeneous surface reaction for CH3 radicals to form CH4, as opposed to a homogeneous gas-phase reaction, is effective in reducing carbon contamination from dimethylzinc. The increase in the flow rate of NH3 increases not only shallow N acceptors but also shallow donors, which prevent p-type conduction.