title: Self-Assembled Formation of Well-Aligned Cu-Te Nano-Rods on Heavily Cu-Doped ZnTe Thin Films.
abstract: Cu doping of ZnTe, which is an important semiconductor for various optoelectronic applications, has been successfully achieved previously by several techniques. However, besides its electrical transport characteristics, other physical and chemical properties of heavily Cu-doped ZnTe have not been reported. We found an interesting self-assembled formation of crystalline well-aligned Cu-Te nano-rods near the surface of heavily Cu-doped ZnTe thin films grown via the molecular beam epitaxy technique. A phenomenological growth model is presented based on the observed crystallographic morphology and measured chemical composition of the nano-rods using various imaging and chemical analysis techniques. When substitutional doping reaches its limit, the extra Cu atoms favor an up-migration toward the surface, leading to a one-dimensional surface modulation and formation of Cu-Te nano-rods, which explain unusual observations on the reflection high energy electron diffraction patterns and apparent resistivity of these thin films. This study provides an insight into some unexpected chemical reactions involved in the heavily Cu-doped ZnTe thin films, which may be applied to other material systems that contain a dopant having strong reactivity with the host matrix.
authors.affiliation: Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Room 4459, Academic Building, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Room 4459, Academic Building, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Man Kit
authors.initials: MK
authors.lastname: Cheng
authors.affiliation: Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Room 4459, Academic Building, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Ying Hoi
authors.initials: YH
authors.lastname: Lai
authors.affiliation: Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Room 4459, Academic Building, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Guanglu
authors.initials: G
authors.lastname: Wei
authors.affiliation: Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Room 4459, Academic Building, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.
authors.forename: Sean Derman
authors.initials: SD
authors.lastname: Yang
authors.affiliation: Department of Physics, South University of Science and Technology of China, 1088 Xueyuan Rd., Nanshan District, Shenzhen, Guangdong, People's Republic of China.
authors.forename: Gan
authors.initials: G
authors.lastname: Wang
authors.affiliation: Faculty of Science and Technology, University of Macau, E11 Avenida da Universidade, Taipa, Macau, China.
authors.forename: Sut Kam
authors.initials: SK
authors.lastname: Ho
authors.affiliation: Faculty of Science and Technology, University of Macau, E11 Avenida da Universidade, Taipa, Macau, China.
authors.forename: Kam Weng
authors.initials: KW
authors.lastname: Tam
authors.affiliation: Department of Physics and William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Room 4459, Academic Building, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China. phiksou@ust.hk.
authors.forename: Iam Keong
authors.initials: IK
authors.lastname: Sou
keywords: Heavily Cu-doped ZnTe; MBE; Self-assembled nano-rods; Surface modulation