Room-temperature luminescence of excitons in ZnO/(Mg,Zn)O multiple-quantum wells on lattice-matched substrates

• Main Authors: Segawa, Y., Kawasaki, M., Ohtomo, A., Makino, T., Chia, C. H., Tuan, N. T., Sun, Handong, Tamura, K., Koinuma, H.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2009
• Subjects: DRNTU::Science::Physics
• Online Access: https://hdl.handle.net/10356/101295; http://hdl.handle.net/10220/6145; http://scitation.aip.org.ezlibproxy1.ntu.edu.sg/getabs/servlet/GetabsServlet?prog=normal&id=APPLAB000077000007000975000001
• Institution: Nanyang Technological University

We report on the optical properties of ZnO/(Mg, Zn)O multiple quantum wells (MQWs) on lattice-matched ScAlMgO4 substrates fabricated by laser molecular-beam epitaxy. As the well layer thickness decreased down to 7 Å, the photoluminescence (PL) and absorption peaks showed a systematic blueshift, consistent with the quantum-size effect. Moreover, a bright PL of free excitons could be observed even at room temperature. As a result, the PL could be tuned in the energy range of 3.3–3.6 eV by choosing the appropriate barrier height and well layer thickness. The widest tunability on the room-temperature luminescence of the excitons could be attained on the basis of the ZnO quantum structure. These favorable properties could not be attained in the MQWs on lattice-mismatched sapphire substrates.