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Hydrogen passivation in nitrogen and chlorinedoped ZnSe films grown by gas source molecular beam epitaxy Appl.The zinc pressure effect in chlorinedoped ZnSe grown by atmospheric metalorganic chemical vapor deposition Deep level transient spectroscopy (DLTS) was used to investigate defect centers in chlorine-doped ZnSe epitaxial films grown by molecular beam epitaxy on (100) nf-GaAs substrates. The resulting carrier concentrations were in the range from 8X1015 to 3.8XlOr' crne3. In low and moderately doped samples two isolated point defects are found, with energy levels at 0.30 and 0.51 eV below the conduction band. The concentration of the dominant trap (at 0.51 eV) is relatively low-of the order of 1Or5 cm-"-and does not depend on the Cl-doping level. The trap exhibits a strong electric field dependence, indicating its donorlike character. Heavily doped samples reveal a single thermal emission peak. The DLTS amplitude of this peak changes as a logarithm of the filling pulse duration, suggesting that the emission originates from spatially extended defects. We compare the DLTS behavior observed on ZnSe:Cl to earlier studies of Ga-doped ZnSe. Our results clearly indicate that Cl is far superior to Ga as an n-type dopant, because-unlike Ga-Cl does not of itself introduce any detectable deep defects into Z&e. -7382

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P-type nitrogen-doped ZnSe grown on n+-GaAs by molecular beam epitaxy has been studied by deep-level transient spectroscopy (DLTS) and double correlation DLTS. To achieve p-type doping of ZnSe, we employed an active nitrogen beam produced by a free-radical plasma source. Four hole traps—with activation energies of 0.22, 0.51, 0.63, and 0.70 eV—were detected by DLTS. Two of these—those at 0.51 and 0.63 eV—have never been observed before in ZnSe. They are probably introduced to the material by nitrogen doping. The properties of the other two traps—at 0.22 and 0.70 eV—support the hypothesis that both of them are associated with native defects, in agreement with earlier reports. To our knowledge this is the first report about direct experimental investigation of deep states in p-type ZnSe.

The impact of air-flow-velocity on the crystallization of m-perovskite is adequately revealed. Through high-air-flow-velocity modification, a compact m-perovskite film with larger crystal grains, decreased defect density and enhanced charge collection ability is obtained.