Photoluminescence, modulation spectroscopy and surface photovoltage characterization of quaternary Zn1-x-yCdxMgySe compounds
An optical characterization of wurtzite Zn1-x-yCdxMgySe crystalline alloys grown by the modified high-pressure Bridgman method has been carried out by temperature-dependent photoluminescence (PL) and contactless electroreflectance (CER) in the temperature range of 103...
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| Autores principales: | , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
D.Ghitu Institute of Electronic Engineering and Nanotechnologies
2011
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/448c12cb8d804a178a65c4a4f9987719 |
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| Sumario: | An optical characterization of wurtzite Zn1-x-yCdxMgySe crystalline alloys grown by the
modified high-pressure Bridgman method has been carried out by temperature-dependent
photoluminescence (PL) and contactless electroreflectance (CER) in the temperature range of
10300 K, and photoreflectance (PR) measurements between 300400 K as well as surface
photovoltage spectroscopy (SPS) at 300 K. Low temperature PL spectra of the investigated
samples consist of an excitonic line, the “edge emission” due to radiative recombination of
shallow donor-acceptor pairs and a broad band related to recombination through deep level
defects. Three excitonic features, A, B and C, in the vicinity of band edge were observed in the
CER and PR spectra. The peak positions of band-edge excitonic features in the PL spectra are
shifted slightly towards lower energies as compared to the lowest corresponding transition
energies of A exciton determined from CER and PR data. The increase of the CER-PL shift with
the increasing of Mg content in the investigated crystals is explained by the rising of
compositional disorder causing the smearing of the band-edge energies. In addition, the
coincidence of energy positions of features obtained from SPS measurements with excitonic
transition energies E0A determined from CER/PR data at 300 K confirm the proper surface
treatment of the samples.
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