Dresden 2003 – scientific programme
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HL: Halbleiterphysik
HL 38: II-VI Halbleiter II
HL 38.1: Talk
Thursday, March 27, 2003, 11:00–11:15, BEY/118
Investigation of the absorption behavior of thin layers of group III nitrides by Photothermal Deflection Spectroscopy and Spectral Resolved Photoconductivity — •Irina Popa, Vadim Lebedev, Volker Cimalla, and Oliver Ambacher — Center for Micro- and Nanotechnologies, Technical University Ilmenau, PF100565, 98693-Ilmenau
The bandgap of group III nitrides (InN, GaN, and AlN) can be varied between 0.6 eV and 6.1 eV depending on the composition of InGaN and AlGaN alloys. The Photothermal Deflection Spectroscopy (PDS) is a powerful tool to investigate the absorbance of group III nitride layers and nanostructures in this range of energies down to values of α d = 10−4 ( α : absorption coefficient, d: layer tickness), needed for the proper design of light detectors and emitters. Information about absorption coefficients and bandgaps are obtained for thick layers as well as for thin quantum wells. In combination with the Spectral Resolved Photoconductivity (SRP), which can be measured with the same experimental set up, it is possible to get information about the density of shallow defects located close to the valence and conduction band edge in addition. We will demonstrate the usefulness of PDS a SRP measurements to evaluate the optical quality of thin AlGaN and InGaN layers grown by molecular beam epitaxy over the whole range of possible compositions.