Excitons and Phonons in GaN. Magnetooptical and Spatially Resolved Investigations

• Authors: A. Hoffmann , L. Eckey , H. Siegle , A. Kaschner , J. Christen , F. Bertram , Q. Liu
• Languages of publication: EN

Abstracts

EN

A comprehensive study of the direct photoluminescence from free-exciton states in GaN using polarization-dependent and magnetooptical measurements is presented. We measured and identified fine-structure splittings in the n=1 state of the A-exciton. From the magnetoluminescence data obtained in fields up to 15 T we determined the g-values of the conduction and valence bands parallel and perpendicular to the c-axis. Self-organized hexagonal GaN pyramids of 5 μm width and covered by six {11̲01} side facets were investigated by spatially resolved cathodoluminescence and micro-Raman spectroscopy. Beside a narrow luminescence peak at 355 nm, originating from the 2 μm thick GaN layer, an additional broad luminescence band was observed from the GaN pyramids around a wavelength of 357 nm. A strong energy shift is found along the {11̲01} pyramidal facets and directly visualized by monochromatic cathodoluminescence images and line scans. In GaN epilayers grown on GaAs substrates a series of sharp modes in the range between 60 cm^{-1} and 250 cm^{-1} for temperatures below 100 K was found. The intensities of these modes increased drastically with decreasing temperature. Raman excitation spectra showed a maximum between 514.5 nm and 568 nm. A comparison of spatially resolved investigations with that of intentionally doped GaN epilayers showed that the in-diffusion of As from the substrate plays an important role. Raman spectra as a function of external fields, like magnetic field and hydrostatic pressure, gave additional information about the defect type and the underlying scattering mechanism.

Keywords

EN

71.35.-y; 78.40.Fy; 78.45.+h

Discipline

• 78.45.+h: Stimulated emission(see also 42.55.-f Lasers)
• 78.40.Fy: Semiconductors
• 71.35.-y: Excitons and related phenomena

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 1998
• Volume: 94
• Issue: 2
• Pages: 125-137

Dates

published

1998-08

Contributors

author

A. Hoffmann

• Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

author

L. Eckey

• Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

author

H. Siegle

• Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

author

A. Kaschner

• Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

author

J. Christen

• Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, PO4120, 39016 Magdeburg, Germany

author

F. Bertram

• Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, PO4120, 39016 Magdeburg, Germany

author

Q. Liu

• Hahn-Meitner Institut Berlin, Theoretische Physik, Glienicker Str. 100, 14109 Berlin, Germany

Identifiers

DOI

10.12693/APhysPolA.94.125