Is the Mg-related GaN blue luminescence deep-level an MgO surface state?
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2023
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| _version_ | 1866915483406565376 |
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| author | Chaulker, Or Haim Turkulets, Yury Shalish, Ilan |
| author_facet | Chaulker, Or Haim Turkulets, Yury Shalish, Ilan |
| contents | Mg is currently the only p-type dopant in technological use in GaN. Its incorporation into the GaN lattice is difficult. It requires a thermal treatment that only partially activates the Mg. To achieve moderate p-type doping requires high doses of Mg that mostly remain inactive. High p-type doping is thus typically achieved at the cost of certain lattice distortion and the creation of defects. Using low-temperature surface photovoltage spectroscopy, we obtain a wide spectrum of optical transitions within the bandgap of Mg-doped GaN. The results reveal an optical transition from the valence band into a deep trap around 0.49 eV above the valence band, along with what appears to be a complimentary transition from the same trap into the conduction band observed at 2.84 eV (coinciding with the energy of the famous Mg-related GaN blue luminescence). The similar shape of the spectra, their complimentary energies within the GaN gap and their opposite nature (hole vs. electron trap) appear to be more than a coincidence suggesting that this is an Mg-related surface state. The density of charge we calculate for this surface state is about 2x10^12 cm-2. We suggest that these small amounts of surface-segregated Mg partially oxidize during the growth and further oxidize during the consecutive Mg-activation heat treatment. This minute quantity of oxidized surface Mg should be about enough to form an Mg-related surface state. Etching the GaN with HCl is shown to affect the photovoltage at the blue-luminescence-related energy. Finally, we show that pure MgO powder produces the same blue luminescence even at the absolute absence of GaN. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2309_17212 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Is the Mg-related GaN blue luminescence deep-level an MgO surface state? Chaulker, Or Haim Turkulets, Yury Shalish, Ilan Materials Science Mg is currently the only p-type dopant in technological use in GaN. Its incorporation into the GaN lattice is difficult. It requires a thermal treatment that only partially activates the Mg. To achieve moderate p-type doping requires high doses of Mg that mostly remain inactive. High p-type doping is thus typically achieved at the cost of certain lattice distortion and the creation of defects. Using low-temperature surface photovoltage spectroscopy, we obtain a wide spectrum of optical transitions within the bandgap of Mg-doped GaN. The results reveal an optical transition from the valence band into a deep trap around 0.49 eV above the valence band, along with what appears to be a complimentary transition from the same trap into the conduction band observed at 2.84 eV (coinciding with the energy of the famous Mg-related GaN blue luminescence). The similar shape of the spectra, their complimentary energies within the GaN gap and their opposite nature (hole vs. electron trap) appear to be more than a coincidence suggesting that this is an Mg-related surface state. The density of charge we calculate for this surface state is about 2x10^12 cm-2. We suggest that these small amounts of surface-segregated Mg partially oxidize during the growth and further oxidize during the consecutive Mg-activation heat treatment. This minute quantity of oxidized surface Mg should be about enough to form an Mg-related surface state. Etching the GaN with HCl is shown to affect the photovoltage at the blue-luminescence-related energy. Finally, we show that pure MgO powder produces the same blue luminescence even at the absolute absence of GaN. |
| title | Is the Mg-related GaN blue luminescence deep-level an MgO surface state? |
| topic | Materials Science |
| url | https://arxiv.org/abs/2309.17212 |