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- Thinh, N.Q., et al.
(author)
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Properties of Ga-interstitial defects in AlxGa 1-xNyP1-y
- 2005
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 71:12
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Journal article (peer-reviewed)abstract
- A detailed account of the experimental results from optically detected magnetic resonance (ODMR) studies of grown-in defects in (Al)GaNP alloys, prepared by molecular beam epitaxy, is presented. The experimental procedure and an in-depth analysis by a spin Hamiltonian lead to the identification of two Gai defects (Gai-A and Gai-B). New information on the electronic properties of these defects and the recombination processes leading to the observation of the ODMR signals will be provided. These defects are deep-level defects. In conditions when the defect is directly involved in radiative recombination of the near-infrared photoluminescence band, the energy level of the Gai-B defect was estimated to be deeper than ~1.2 eV from either the conduction or valence band edge. In most cases, however, these defects act as nonradiative recombination centers, reducing the efficiency of light emission from the alloys. They can thus undermine the performance of potential photonic devices. High thermal stability is observed for these defects. ©2005 The American Physical Society.
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- Buyanova, Irina, 1960-, et al.
(author)
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Hydrogen passivation of nitrogen in GaNAs and GaNP alloys : How many H atoms are required for each N atom?
- 2007
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:2, s. 021920-
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Journal article (peer-reviewed)abstract
- Secondary ion mass spectrometry and photoluminescence are employed to evaluate the origin and efficiency of hydrogen passivation of nitrogen in GaNAs and GaNP. The hydrogen profiles are found to closely follow the N distributions, providing unambiguous evidence for their preferential binding as the dominant mechanism for neutralization of N-induced modifications in the electronic structure of the materials. Though the exact number of H atoms involved in passivation may depend on the conditions of the H treatment and the host matrixes, it is generally found that more than three H atoms are required to bind to a N atom to achieve full passivation for both alloys. © 2007 American Institute of Physics.
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| 8. |
- Buyanova, Irina, 1960-, et al.
(author)
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Modeling of band gap properties of GaInNP alloys lattice matched to GaAs
- 2006
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:3, s. 31907-
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Journal article (peer-reviewed)abstract
- Compositional and temperature dependences of the band gap energies of GaInNP alloys, which are lattice matched to GaAs, are determined and modeled by a band anticrossing (BAC) interaction between the localized state of the isolated NP and extended host states. The BAC parameters are deduced as EN =2.1±0.1 eV and CMN =1.7±0.2 eV. The low value of the coupling parameter CMN implies weaker coupling of the N level with the host matrix, presumably due to short range ordering effects, similar to the case of GaInNAs alloys with a high In content. The obtained information is important for future modeling of the electronic structure of the alloys. © 2006 American Institute of Physics.
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| 9. |
- Buyanova, Irina, 1960-, et al.
(author)
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Role of nitrogen in photoluminescence up-conversion in GaInNP/GaAs heterostructures
- 2007
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In: AIP Conference Proceedings / Volume 893. - : American Institute of Physics (AIP). ; , s. 381-382
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Conference paper (other academic/artistic)abstract
- Alloying of disordered GaInP with nitrogen is shown to lead to very efficient PLU in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy (GS‐MBE). This is attributed to the N‐induced changes in the band alignment at the GaInNP/GaAs heterointerface from the type I for the N‐free structure to the type II in the samples with N compositions exceeding 0.5%. Based on the performed excitation power dependent measurements, a possible mechanism for the energy upconversion is suggested as being due to the two‐step two‐photon absorption. The photon recycling effect is shown to be important for the structures with N=1%, from time‐resolved PL measurements. © 2007 American Institute of Physics
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- Izadifard, Morteza, et al.
(author)
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Band alignment in GaInNP/GaAs heterostructures grown by gas-source molecular-beam epitaxy
- 2005
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:26, s. 261904-
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Journal article (peer-reviewed)abstract
- Low-temperature photoluminescence (PL), PL excitation, and optically detected cyclotron resonance measurements are employed to determine band alignment in GaInNP/GaAs heterostructures grown by gas-source molecular-beam epitaxy. The type II band alignment at the Ga0.46In0.54NxP1−x/GaAs interface is concluded for the alloys with x ≥ 0.5% based on (i) highly efficient PL upconversion observed in the N containing samples and (ii) appearance of a near-infrared PL emission attributed to the spatially indirect type II transitions. Compositional dependence of the conduction band offset at the Ga1−yInyNxP1−x/GaAs interface is also estimated.
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| 12. |
- Izadifard, Morteza, et al.
(author)
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Photoluminescence upconversion in GaInNP/GaAs heterostructures grown by gas source molecular beam epitaxy
- 2006
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 99:7, s. 073515-
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Journal article (peer-reviewed)abstract
- Properties of photoluminescence (PL) upconversion (PLU) in GaInNP/GaAs heterostructures are studied in detail by employing a number of optical spectroscopies. Based on excitation power dependent and temperature dependent PL measurements, the upconverted PL from GaInNP under optical excitation below its band gap is attributed to radiative transitions involving spatially separated localized electron-hole pairs, which is of a similar origin as the near-band-gap emission detected under optical excitation above the GaInNP band gap. The PLU process is shown to be largely promoted by increasing N content in the GaInNP alloys, due to a N-induced change in the band alignment at the GaInNP/GaAs heterointerface from the type I in the N-free structure to the type II in the samples with N compositions exceeding 0.5%. A possible mechanism for the energy upconversion is discussed in terms of two-step two-photon absorption. The photon recycling effect is shown to be important for the structures with N = 1%.
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- Izadifard, Morteza, et al.
(author)
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Radiative recombination of GaInNP alloys lattice matched to GaAs
- 2006
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:1, s. 011919-
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Journal article (peer-reviewed)abstract
- Cw- and time-resolved photoluminescence (PL) spectroscopy is employed to evaluate dominant mechanisms for light emission in GayIn1−yNxP1−x alloys grown by gas source molecular-beam epitaxy on GaAs substrates. Different from other direct band gap dilute nitrides, the low temperature PL emission was shown to be largely attributed to radiative transitions involving spatially separated localized electron-hole pairs. The observed charge separation is tentatively attributed to the long range CuPt ordering promoted by the presence of nitrogen.
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| 14. |
- Thinh, N.Q., et al.
(author)
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Ga-interstitial related defects in Ga(Al)NP
- 2005
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In: 27th Int. Conf. on the Physics of Semicond,2004. - : American Institute of Physics (AIP). ; , s. 259-260
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Conference paper (other academic/artistic)abstract
- Twogrown-in Ga interstitial (Gai) defects in Ga(Al)NP are identified byoptically detected magnetic resonance (ODMR), from the characteristic hyperfine (HF)structure associated with the nuclear spin I=3/2 of the Gai.Both defects are concluded to be Gai-related complexes. Effects ofAl and N compositions on the HF structure shed lighton local surrounding of the Gai. ©2005 American Institute ofPhysics
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| 15. |
- Vorona, Igor, et al.
(author)
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Magnetic resonance signatures of grown-in defects in GaInNP alloys grown on a GaAs substrate
- 2005
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:22, s. 222110-
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Journal article (peer-reviewed)abstract
- Dilute-nitride Ga0.44In0.56NyP1-y alloys with y=0-0.02, grown on a GaAs substrate using gas-source molecular beam epitaxy, are studied by the optically detected magnetic resonance (ODMR) technique. Grown-in paramagnetic defects were found to act as centers of nonradiative recombination. Resolved hyperfine structure for one of the detected ODMR signals suggests involvement of a Ga-interstitial or an As-antisite in the structure of the related defect. © 2005 American Institute of Physics.
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| 16. |
- Wang, Xingjun, 1972-, et al.
(author)
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Effects of grown-in defects on electron spin polarization in dilute nitride alloys
- 2008
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In: 7th International Conference on Nitride Semiconductors ICNS-7,2007. - phys. stat. sol. (c) vol. 5 : WILEYVCH Verlag GmbH & Co. KGaA, Weinheim. ; , s. 1529-
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Conference paper (peer-reviewed)abstract
- Strong electron spin polarization in GaNAs epilayers and multiple quantum well structures is observed upon optical orientation at room temperature. The effect is explained in terms of spin dependent recombination (SDR) involving deep paramagnetic defects formed upon N incorporation in GaNAs. Concentration of the corresponding defects is shown to be enhanced during growth at low temperatures but is suppressed by post-growth annealing. Optically detected magnetic resonance (ODMR) measurements performed in the studied structures reveal two paramagnetic defects participating in carrier recombination. One of them is identified as a complex involving AsGa antisite. Correlation between concentrations of the defects monitored via ODMR and in optical orientation measurements is observed which suggests that the same defects may be involved in both processes.
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| 17. |
- Wang, Xingjun, 1972-, et al.
(author)
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Generating strong electron spin polarization at room temperature in GaNAs via spin-dependent recombination
- 2008
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In: 5th International Conference on Physics and Applications of Spin-related Phenomena in Semiconductors PASPS V,2008.
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Conference paper (other academic/artistic)abstract
- The issues of generating and maintaining carrier spin polarization in semiconductors have attracted intense research efforts, not only due to their importance for future applications in spintronics but also due to the intriguing physics underpinning spin-dependent phenomena. Entering the family of semiconductors that exhibit attractive spin-dependent properties, Ga(In)NAs was most recently found to exhibit strong spin polarization of conducting electrons at room temperature upon N incorporation with an extremely long apparent spin lifetime. In this work we have uncovered the origin of the astonishing effect as being due to strong spin dependent recombination (SDR) via defects, by a combination of optical orientation and optically detected magnetic resonance (ODMR) studies. We were able to identify Ga self-interstitials and an As antisite complex to be the dominant defects participating in the SDR process. The involvement of these defects were unambiguously established by their unique spin-resonance signatures derived from the hyperfine interaction between the localized unpaired electron spin and nuclear spins (I=3/2) of the As and Ga atom - the core of the defects. These defects dominate in carrier capture and recombination leading to the observed strong dynamic polarization of electron spins. Further confirmation was found by the effects of growth conditions and post-growth treatments on the defect density that were closely correlated with the electron spin polarization.
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