Properties of DX centers in AlxGa1−xAs co-doped with boron and silicon

Mooney, P. M.; Tischler, M. A.; Parker, B.

doi:10.1063/1.105873

Cited by 8 publications

(6 citation statements)

References 13 publications

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“…These states lead to very long‐lived (presumably spin‐forbidden) optical transitions, which become significantly faster, when the electrons are excited to their respective slightly higher lying more extended “normal” EMT‐like donor states. In contrast to the well‐known DX centers in the “classical” III–V materials like AlGaAs and AlInGaP , for which the DX state is typically lower by ≈1 eV relative to the EMT D° state, these DX states in AlN are still lying relatively close. This can be understood, because a significant lowering of the D° state requires a large lattice relaxation approaching the opposite charges of the donor and its next neighbors, which costs too much elastic energy in such a very hard material like AlN .…”

Section: Discussionmentioning

confidence: 64%

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Optical signatures of silicon and oxygen related DX centers in AlN

Thonke

Lamprecht

Collazo

et al. 2017

Phys. Status Solidi A

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Bulk AlN crystals typically contain high concentrations of oxygen, silicon, and carbon À as also state-of-the art epitaxial layers typically do, depending on the specific growth conditions. In optical spectroscopy, such crystals show broad bands in the region from 2-5 eV in absorption and emission. We investigated several emission bands in the range from 1.4 to 1.9 eV, especially those centred at 2.0 and 2.4 eV, which under below-bandgap excitation with a 325 nm laser dominate the photoluminescence (PL) spectra both at low and at room temperature. We find clear indications that all these transitions occur between different states of the shallow donors Si or O, and deep acceptors. The donors undergo lattice relaxation and form DX centres. Depending on temperature, the initial state is either a long-lived (S ¼ 1) DXcentre state of the donors, a shallow EMT-like conventional donor state, or a free electron À with markedly different relaxation times for the optical transitions under below-bandgap excitation. The acceptor involved in these PL bands is likely linked to aluminum vacancies. Based on our data, we develop configuration coordinate diagrams and a combined level scheme for multiple transitions in the range from 1.4 to 2.4 eV.Tentative level scheme for PL bands observed in AlN in the range from 1.4 to 2.4 eV.

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Section: Discussionmentioning

confidence: 64%

“…The formation of the shallow donor‐related DX centres by capture of a second electron and subsequent large lattice relaxation is a well‐known and thoroughly studied phenomenon in AlGaAs . Later, the same phenomenon was found for (Al,Ga,In)P , and also for II–VI semiconductors as well as for AlGaN and AlN .…”

Section: Introductionmentioning

confidence: 69%

Optical signatures of silicon and oxygen related DX centers in AlN

Thonke

Lamprecht

Collazo

et al. 2017

Phys. Status Solidi A

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“…6 Excitation of DX centers using visible light has been studied extensively in various semiconductor compounds over the last few decades. [7][8][9][10] Here, we demonstrate that irradiation by x rays can also induce persistent photoconductivity in Si-doped Al 0.35 Ga 0.65 As. While phenomenologically the persistent photoconductivity and its erasure upon annealing is similar to the x-ray induced metallization observed in a transition metal oxide, 11 the underlying mechanisms are quite different.…”

Section: Introductionmentioning

confidence: 93%

X-ray induced persistent photoconductivity in Si-doped Al0.35Ga0.65As

Soh

Aeppli

Zimmermann

et al. 2001

Journal of Applied Physics

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We demonstrate that X-ray irradiation can be used to induce an insulator-metal transition in Si-doped Al0.35Ga0.65As, a semiconductor with DX centers. The excitation mechanism of the DX centers into their shallow donor state was revealed by studying the photoconductance along with fluorescence. The photoconductance as a function of incident X-ray energy exhibits an edge both at the Ga and As K-edge, implying that core-hole excitation of Ga and As are efficient primary steps for the excitation of DX centers. A high quantum yield (≫ 1) suggests that the excitation is indirect and nonlocal, due to secondary electrons, holes, and fluorescence photons.

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“…The extremely large band gap bowing coefficient allows the GaInNAs alloy to maintain lattice-matched to GaAs, with a wide range of tunable band gap energies smaller than GaAs band gap for x$3y. However, the crystal quality of GaInNAs tends to degrade with increasing N concentration possibly due to the phase separation even though the amount of strain in the layer decreases.The effect of persistent photoconductivity (PPC) has been observed in a large number of III-V and II-VI compounds with various dopants and different structures: bulk, heterojunctions, modulation-doped or delta-doped layers [5][6][7][8][9][10]. It is known that the PPC can be described as a light-induced change in photoconductivity which would persist after removing the excitation.…”

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confidence: 99%

“…The effect of persistent photoconductivity (PPC) has been observed in a large number of III-V and II-VI compounds with various dopants and different structures: bulk, heterojunctions, modulation-doped or delta-doped layers [5][6][7][8][9][10]. It is known that the PPC can be described as a light-induced change in photoconductivity which would persist after removing the excitation.…”

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confidence: 99%