화학공학소재연구정보센터
Journal of Vacuum Science & Technology A, Vol.14, No.4, 2269-2274, 1996
Investigation of Deep Levels in ZnSe-Cl Films Grown by Molecular-Beam Epitaxy
Using ZnCl2 as a doping source, we have grown epitaxial layers of Cl-doped ZnSe onto GaAs(100) substrates at a temperature of 285 degrees C by molecular beam epitaxy. The carrier concentration was controlled by the ZnCl2 source temperature. The maximum carrier concentration obtained was 1.2x10(19) cm(-3) with a resistivity of 2.7x10(-3) Omega cm. Higher doses of Cl atoms tend to decrease free carrier concentration and introduce additional defects; this effect was consistent with an increase of deep-level photoluminescence emission. From deep-level transient spectroscopy measurements we determined the presence of four traps with energy levels E(c) around 0.50, 0.68, 0.74, and 1.20 eV. The last three traps have not been previously reported. One of them, E(c) similar to 0.74 eV, presents a clear dependence with Cl concentration and thus can affect the performance of ZnSe:Cl-based devices. The microscopic nature of these traps is discussed in terms of Zn vacancies (V-Zn) and V-Zn-Cl complexes.