Free-Standing Undoped ZnO Microtubes with Rich and Stable Shallow Acceptors.
Fabrication of reliable large-sized p-ZnO is a major challenge to realise ZnO-based electronic device applications. Here we report a novel technique to grow high-quality free-standing undoped acceptor-rich ZnO (A-ZnO) microtubes with dimensions of ~100 μm (in diameter) × 5 mm (in length) by optical vapour supersaturated precipitation. The A-ZnO exhibits long lifetimes (>1 year) against compensation/lattice-relaxation and the stable shallow acceptors with binding energy of ~127 meV are confirmed from Zn vacancies. The A-ZnO provides a possibility for a mimetic p-n homojunction diode with n(+)-ZnO:Sn. The high concentrations of holes in A-ZnO and electrons in n(+)-ZnO make the dual diffusion possible to form a depletion layer. The diode threshold voltage, turn-on voltage, reverse saturated current and reverse breakdown voltage are 0.72 V, 1.90 V, <10 μA and >15 V, respectively. The A-ZnO also demonstrates quenching-free donor-acceptor-pairs (DAP) emission located in 390-414 nm with temperature of 270-470 K. Combining the temperature-dependent DAP violet emission with native green emission, the visible luminescence of A-ZnO microtube can be modulated in a wide region of colour space across white light. The present work opens up new opportunities to achieve ZnO with rich and stable acceptors instead of p-ZnO for a variety of potential applications.
Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China.
Qiang
Q
Wang
Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China.
Yinzhou
Y
Yan
Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China.|Beijing Engineering Research Center of 3D Printing for Digital Medical Health, Beijing University of Technology, Beijing 100124, China.
Yong
Y
Zeng
Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China.
Yue
Y
Lu
College of Applied Sciences, Beijing University of Technology, Beijing 100124, China.
Liang
L
Chen
Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China.
Yijian
Y
Jiang