N-type doping of lattice-matched ZnCdSe and ZnxCdyMg1-x-ySe epilayers on InP using ZnCl2

Chlorine on Se-site forms a shallow donor for ZnSe. In this article, we use Cl, obtained from ZnCl2, as the n-type dopant for ZnxCdyMg1-x-ySe lattice matched to InP, a new wide band gap II-VI material grown by molecular beam epitaxy. An 800 Angstrom p-type doped InGaAs buffer layer was grown to improve the doping behavior, consistent with improved crystalline quality. The highest free-carrier concentrations measured by Hall effect are 7 x 10(18) cm(-3) with mobility of 240 cm(2)/V s and 3 x 10(18) cm(-3) with mobility of 230 cm(2)/V s for Zn0.5Cd0.5Se (77 K E-g=2.17 eV) and ZnCdMgSe (77 K E-g= 2.74 eV), respectively. A small systematic reduction of maximum carrier concentration was observed as the quaternary layer band gap is increased. No deep level emission is introduced by the chlorine dopant. High n-type doping levels, consistent with semiconductor laser applications were achieved for quaternaries of band gaps as high as 2.9 eV. (C) 1998 American Institute of Physics.