Hydrogen passivation of nitrogen-related energy levels in ZnSe and ZnSSe grown by MBE

In previous work we reported the observation of three hole traps in N-doped ZnSe and ZnSxSe1-x films grown by MBE. We attributed a trap T1 at E-v + 0.11 eV in ZnSe to a dominating nitrogen acceptor, but traps T2 at E-v + 0.46 and T3 at E-v + 0.56 eV to the N-doping process. In the present study we investigated the effect of hydrogenation on these hole traps. We found that samples with net acceptor concentrations less than few times 10(16) cm(-3) become highly resistive after the hydrogenation. In samples which remained conductive the hydrogenation caused a decrease in the DLTS peak heights of T2 and T3 within 0.4-0.5 mu m from the surface. In samples with net acceptor concentration around 2-5 x 10(16) cm(-3) we also observe a similar decrease in the DLTS peak height of level T1 and net charge density which shows its role in the hole conductivity of the samples. Hydrogenation of samples with net acceptor densities in the 10(17) cm(-3) range did not affect the net charge density or height of T1 much. (C) 1999 Elsevier Science B.V. All rights reserved.