ZnO/(ZnMg)O single quantum wells with high Mg content graded barriers

Journal Article · Fri Jun 01 04:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4723642· OSTI ID:22089227

Laumer, Bernhard ^[1]; Schuster, Fabian; Wassner, Thomas A.; Stutzmann, Martin ^[1]; Rohnke, Marcus ^[2]; Schoermann, Joerg; Eickhoff, Martin ^[3]

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1. Walter Schottky Institut and Physics Department, Technische Universitaet Muenchen, Am Coulombwall 4, 85748 Garching (Germany)
2. Institut fuer Physikalische Chemie, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 58, 35392 Giessen (Germany)
3. I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)

ZnO/Zn{sub 1-x}Mg{sub x}O single quantum wells (SQWs) were grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. Compositional grading allows the application of optimized growth conditions for the fabrication of Zn{sub 1-x}Mg{sub x}O barriers with high crystalline quality and a maximum Mg content of x = 0.23. High resolution x-ray diffraction reveals partial relaxation of the graded barriers. Due to exciton localization, the SQW emission is found to consist of contributions from donor-bound and free excitons. While for narrow SQWs with well width d{sub W}{<=}2.5nm, the observed increase of the exciton binding energy is caused by quantum confinement, the drop of the photoluminescence emission below the ZnO bulk value found for wide SQWs is attributed to the quantum-confined Stark effect. For a Mg content of x = 0.23, a built-in electric field of 630 kV/cm is extracted, giving rise to a decrease of the exciton binding energy and rapid thermal quenching of the SQW emission characterized by an activation energy of (24 {+-} 4) meV for d{sub W} = 8.3 nm.

• OSTI ID: 22089227
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 111; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
ACTIVATION ENERGY
BINDING ENERGY
CONFINEMENT
ELECTRIC FIELDS
EXCITONS
MAGNESIUM COMPOUNDS
MOLECULAR BEAM EPITAXY
PHOTOLUMINESCENCE
QUANTUM WELLS
QUENCHING
RELAXATION
RESOLUTION
SAPPHIRE
SEMICONDUCTOR MATERIALS
SOLIDIFICATION
STARK EFFECT
SUBSTRATES
X-RAY DIFFRACTION
ZINC OXIDES