title: Comparison of emission characteristics between the CdZnO/ZnO quantum wells on ZnO and GaN templates.
abstract: CdZnO/ZnO quantum well (QW) samples are grown on GaN and ZnO templates with plasma-assisted molecular beam epitaxy under different conditions of substrate temperature, Cd effusion cell temperature, and O(2) flow rate for emission characteristics comparison. It is found that the Cd incorporation on the ZnO template is generally lower, when compared with that on the GaN template, such that the O(2) flow rate needs to be reduced for stoichiometric CdZnO/ZnO QW growth on the ZnO template. Besides the wurtzite (wt) CdZnO structure, the rock-salt (rs) CdZnO structure exists in the CdZnO well layers when the total Cd content is high. The rs structure may dominate over the wt structure in photoluminescence intensity when the total Cd content is high. In either group of samples on the GaN and ZnO templates, the emission efficiency first increases and then decreases with increasing total Cd content. The low emission efficiency at low (high) Cd content is attributed to the weaker quantum confinement (the poorer crystal quality) of the QWs. The emission efficiencies of the QW samples on the GaN template are generally higher than those on the ZnO template. The carrier localization behavior in a CdZnO/ZnO QW, grown on either GaN or ZnO template, is significantly weaker than that in an InGaN/GaN QW. The strength of the quantum-confined Stark effect generally increases with increasing Cd content in either group of samples on the GaN and ZnO templates.
authors.affiliation: Institute of Photonics and Optoelectronics, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan.
authors.forename: Shao-Ying
authors.initials: SY
authors.lastname: Ting
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Yao
authors.forename: Wei-Lun
authors.initials: WL
authors.lastname: Chung
authors.forename: Wen-Ming
authors.initials: WM
authors.lastname: Chang
authors.forename: Chih-Yen
authors.initials: CY
authors.lastname: Chen
authors.forename: Hao-Tsung
authors.initials: HT
authors.lastname: Chen
authors.forename: Che-Hao
authors.initials: CH
authors.lastname: Liao
authors.forename: Horng-Shyang
authors.initials: HS
authors.lastname: Chen
authors.forename: Chieh
authors.initials: C
authors.lastname: Hsieh
authors.forename: C C
authors.initials: CC
authors.lastname: Yang
mesh_terms: D000327:Adsorption; D019187:Cadmium Compounds / Q000737:chemistry*; D005708:Gallium / Q000737:chemistry*; D008027:Light; D008422:Materials Testing; D054802:Molecular Imprinting / Q000379:methods*; D010087:Oxides / Q000737:chemistry*; D045663:Quantum Dots; D012542:Scattering, Radiation; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D010087:Oxides; C029663:cadmium oxide; C473348:gallium nitride; D005708:Gallium; D015034:Zinc Oxide