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  • 1
    Online Resource
    Online Resource
    Displaced hysteresis loop and microstructure of Cu-Mn-Al alloys
    AIP Publishing ; 1980
    In:  Applied Physics Letters Vol. 36, No. 10 ( 1980-05-15), p. 862-864
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 36, No. 10 ( 1980-05-15), p. 862-864
    Abstract: The 44.7Cu-20.6Mn-34.7A1 (at. %) alloy aged at 300 °C for 1 h, which exhibits the high coercive force of 5–6 kOe at 300 K, has been found to show displaced hysteresis loop when it is cooled to 77 K in a magnetic field. The displaced hysteresis loop is believed to be due to the statistical fluctuations in the local Mn concentration and the coexistence of ferromagnetic and antiferromagnetic interactions between Mn atoms of different separation.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/1.91351
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 1980
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 2
    Online Resource
    Online Resource
    Displaced hysteresis loop of Cu-Mn-Al alloy
    AIP Publishing ; 1981
    In:  Journal of Applied Physics Vol. 52, No. 9 ( 1981-09-01), p. 5751-5755
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 52, No. 9 ( 1981-09-01), p. 5751-5755
    Abstract: The 44.7Cu-20.6Mn-34.7Al (at. %) alloy, which exhibits a very high coercive force after aging at 300 °C, has been found to show a displaced hysteresis loop when it is cooled to 77 K in a magnetic field. The hysteresis loop of the sample which aged for more than 60 min at 300 °C is shifted along the magnetization axis instead of along the field axis. The magnetization measured at 300 K for a maximum applied field of 15 kOe becomes larger than that at 77 K after aging for 45 min at 300 °C. In the magnetization versus temperature curves of the sample aged for more than 45 min at 300 °C, the magnetization decreases monotonically with decreasing temperature. The increase of coercive force, which is obtained in the sample aged for more than 45 min at 300 °C, corresponds to the increase of the displacement of the hysteresis loop. These magnetic behaviors are considered to be caused by the exchange anisotropy interaction between the regions of ferromagnetic Heusler or Mn-poor phase and ferrimagnetic or antiferromagnetic Mn-rich phase.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.329463
    Language: English
    Publisher: AIP Publishing
    Publication Date: 1981
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
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  • 3
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    Online Resource
    Graphene nanoribbons on hexagonal boron nitride: Deposition and transport characterization
    AIP Publishing ; 2019
    In:  Applied Physics Letters Vol. 114, No. 17 ( 2019-04-29)
    Details
    In: Applied Physics Letters, AIP Publishing, Vol. 114, No. 17 ( 2019-04-29)
    Abstract: Chemically synthesized “cove”-type graphene nanoribbons (cGNRs) of different widths were brought into dispersion and drop-cast onto exfoliated hexagonal boron nitride (hBN) on a Si/SiO2 chip. Using AFM, we observed that the cGNRs form ordered domains aligned along the crystallographic axes of the hBN. Using electron beam lithography and metallization, we contacted the cGNRs with NiCr/Au or Pd contacts and measured their I-V characteristics. The transport through the ribbons was dominated by the Schottky behavior of the contacts between the metal and the ribbon.
    Type of Medium: Online Resource
    ISSN: 0003-6951 , 1077-3118
    URL: Article
    DOI: 10.1063/1.5065568
    RVK:
    UA 1000
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2019
    detail.hit.zdb_id: 211245-0
    detail.hit.zdb_id: 1469436-0
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  • 4
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    Online Resource
    Defect evolution in Mg ions implanted GaN upon high temperature and ultrahigh N2 partial pressure annealing: Transmission electron microscopy analysis
    AIP Publishing ; 2020
    In:  Journal of Applied Physics Vol. 127, No. 10 ( 2020-03-14)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 127, No. 10 ( 2020-03-14)
    Abstract: Defects in Mg ion-implanted GaN epitaxial layers formed after annealing at 1573 K and at 1753 K were analyzed by transmission electron microscopy. Degradation of the GaN surface, which occurs at temperatures higher than about 1573 K, was avoided by ultra-high-pressure annealing under a N2 atmosphere at 1 GPa. Annealing for damage recovery in ion-implanted compound semiconductors generally requires temperatures at about two-thirds of their melting point, which is reportedly 2518 K or higher for GaN. Thus, defect analysis in ion-implanted GaN annealed at temperatures higher than 1573 K is necessary to understand the defect recovery. Atomic-resolution transmission electron microscopy analysis showed that interstitial-type extended defects and inversion domains with Mg segregation were formed during the annealing at 1573 K. These defects were not observed in a sample annealed at 1753 K; instead, vacancy-type extended defects were formed. Such evolution of defects can be explained by previous theoretical studies that indicated that the migration energy of vacancy-type defects is higher than that of interstitial-type defects. Moreover, the formation of vacancy-type extended defects implies a reduction in the concentrations of vacancies and their complexes. Since the vacancies and their complexes can compensate for Mg acceptors, their reduced concentration should increase the acceptor activation efficiency. Also, the disappearance of Mg segregation during high-temperature annealing should increase the activation efficiency since the segregated Mg atoms are electrically inactive. It is thus concluded that the evolution of defects caused by high-temperature annealing above 1573 K increases the activation efficiency of acceptors in Mg ion-implanted GaN.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.5140410
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2020
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
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  • 5
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    Online Resource
    Analysis of channel mobility in GaN-based metal-oxide-semiconductor field-effect transistors
    AIP Publishing ; 2021
    In:  Journal of Applied Physics Vol. 129, No. 8 ( 2021-02-28)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 129, No. 8 ( 2021-02-28)
    Abstract: The factors limiting channel mobility in AlSiO/p-type GaN-based metal-oxide-semiconductor field-effect transistors (MOSFETs) were systematically investigated. MOSFETs with various thin interfacial layers (ILs) between Al0.78Si0.22Oy films and Mg-doped GaN layers were prepared and found to exhibit different channel mobilities. The maximum effective mobility showed a significant correlation with the threshold voltage (Vt) and the hysteresis (ΔVt) in the transfer characteristics of these devices, such that the mobility decreased with increasing Vt and ΔVt. This effect can be explained by electron capture in and emission from border traps situated near the conduction band minimum for GaN. The insertion of a 3-nm-thick SiO2 IL drastically enhanced the effective mobility and simultaneously reduced the ΔVt value. Hall effect measurements with an applied gate voltage were used to determine the mobility of free electrons while excluding electrons captured in the border traps. The Hall effect mobility was much higher than the effective mobility, indicating that mobility was in fact reduced by the capture of electrons by the border traps. The ratio of electrons captured by border traps to the overall electrons induced by a gate bias was greatly lowered in a MOSFET incorporating a SiO2 IL. When a high vertical electric field of approximately 1 MV/cm was present in the device channel, the Hall effect mobility was slightly increased following the insertion of an IL. These results suggest that the IL reduced the interfacial roughness and/or affected the screening out of scattering due to potential fluctuations of the AlSiO.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/5.0040700
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
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  • 6
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    Online Resource
    Contribution of the carbon-originated hole trap to slow decays of photoluminescence and photoconductivity in homoepitaxial n-type GaN layers
    AIP Publishing ; 2021
    In:  Journal of Applied Physics Vol. 129, No. 11 ( 2021-03-21)
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 129, No. 11 ( 2021-03-21)
    Abstract: N-type GaN epitaxial layers grown via metal organic vapor-phase epitaxy typically exhibit a yellow luminescence (YL) band owing to carbon-related deep levels in the photoluminescence spectra. The decay of YL after pulse excitation involves a long time constant (∼0.2 ms at room temperature), whereas microwave photoconductivity decay (μ-PCD) curves show the corresponding component of the time constant. To clarify the origin of the long decay time, the temperature-dependent time constants of YL decay and μ-PCD curves are analyzed using a numerical model based on rate equations for trapping and emission through a deep level. The characteristics of the decays are well reproduced by a recombination model using a hole trap H1 at an energy of EV + 0.88 eV because of the acceptor-like state of carbon on a nitrogen site (CN) whose electron capture cross section (σn) is estimated to be 3 × 10−21 cm2. The slow decay in μ-PCD signals indicates that the electrons before being captured to H1 traps are free electrons in the conduction band. These findings indicate that the slow recombination process through CN results in tail currents in the turn-off switching periods of devices.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/5.0041287
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
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  • 7
    Online Resource
    Online Resource
    Exchange anisotropy in Cu-Mn-Al alloy
    AIP Publishing ; 1982
    In:  Journal of Applied Physics Vol. 53, No. 3 ( 1982-03-01), p. 1655-1659
    Details
    In: Journal of Applied Physics, AIP Publishing, Vol. 53, No. 3 ( 1982-03-01), p. 1655-1659
    Abstract: The 44.7Cu-20.6Mn-34.7Al(at. %) alloy in the composition range between the Heusler phase and the κ phase exhibits remarkably constricted hysteresis loops and high coercive force after annealing at about 300 °C. It has been found that this alloy shows displaced hysteresis loops at room temperature when cooled down from 350 °C in a magnetic field and that the hysteresis loops shift along the magnetization axis, not along the field axis, when the alloy is cooled to 77 K in a magnetic field. Broad rounded maxima of magnetization are observed at about 250 °C for the sample quenched from 380 °C in thermomagnetic measurements. The characteristics of the magnetic behavior are similar to those reported for mictomagnetic alloys, e.g., Cu-Mn alloys. The high coercive forces and the displaced and constricted hysteresis loops observed in the 44.7Cu-20.6Mn-34.7Al alloy are supposed to be attributed to the exchange anisotropy interactions between the ferromagnetic domains of the Heusler phase and the antiferromagnetic Mn-rich domains.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    URL: Article
    DOI: 10.1063/1.331627
    Language: English
    Publisher: AIP Publishing
    Publication Date: 1982
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
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