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Masaaki Tanaka - One of the best experts on this subject based on the ideXlab platform.

  • Planar Hall Effect and Magnetic Anisotropy in a Mn δ‐Doped Gaas/p‐AlGaas Heterostructure
    IEEJ Transactions on Electrical and Electronic Engineering, 2008
    Co-Authors: Ahsan M. Nazmul, Hung-ta Lin, Shinobu Ohya, Masaaki Tanaka
    Abstract:

    We have studied the planar Hall effect (PHE) in a Mn δ-Doped Gaas-based heterostructure consisting of Mn δ-Doped Gaas and p-type AlGaas. Distinct and large PHE, and a specific in-plane uniaxial magnetic anisotropy were observed below the ferromagnetic transition temperature (TC). This uniaxial in-plane magnetic anisotropy is found dominant over the biaxial cubic anisotropy, and is clearly identified by the angular dependence of PHE. This observation is quantitatively discussed in terms of two models of magnetization reversal; the coherent rotation model and the domain-wall motion model. The model calculation fit to the experimental results make it possible to determine the uniaxial and cubic anisotropy fields and examine the behavior of magnetization reversal. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

  • ferromagnetism and high curie temperature in semiconductor heterostructures with mn δ Doped Gaas and p type selective doping
    Physical Review B, 2003
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    The interaction between the magnetic dopants (Mn) and 2-dimensional hole gas (2DHG) in Mn \ensuremath{\delta}-Doped Gaas/Be-Doped $p$-type AlGaas heterostructures, where holes were supplied from the Be-Doped AlGaas to the Mn \ensuremath{\delta}-Doped Gaas, realized ferromagnetic ordering. The Curie temperature ${T}_{\mathrm{C}}$ of the heterostructure prepared with suitable growth conditions was 172 K, highest among the ${T}_{\mathrm{C}}$ values reported in III-V (InAs, Gaas) magnetic semiconductors.

  • mbe growth structural and transport properties of mn δ Doped Gaas layers
    Journal of Crystal Growth, 2003
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    We have grown Mn δ-Doped Gaas layers by molecular beam epitaxy with various Mn sheet concentrations (δMn defined in the monolayer (ML) unit. Structural analyses using cross-sectional transmission electron microscopy and secondary ion mass spectroscopy revealed that when δMnis below I ML, Mn dopants are abruptly confined within 2-3 ML without lattice dislocations and clusters, and also without diffusion and surface segregation. Characterizations on the thermal stability of the doping profiles showed that the profiles retained abruptness even at elevated growth temperature T, = 400°C without diffusion and significant segregation. Strong surface segregation of Mn atoms, lattice dislocations, and MnAs clusters appeared when θMn exceeds 1ML. The transport properties of Mn δ-Doped Gaas layers without and with selectively p-type doping are also presented.

  • Transport properties of Mn δ-Doped Gaas and the effect of selective doping
    Applied Physics Letters, 2002
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    We have grown Mn δ-Doped Gaas layers on Gaas(001) substrates by molecular beam epitaxy. Secondary ion mass spectroscopy and transmission electron microscopy revealed that Mn dopants were abruptly confined. The doping profiles still retained abruptness even at elevated growth temperature up to 400 °C. Mn δ-Doped Gaas samples showed high resistivity at low temperature and did not show a ferromagnetic behavior. However, in a selectively Doped heterostructure (Mn δ-Doped Gaas / Be-Doped AlGaas), where holes were supplied from the Be-Doped AlGaas layer, a ferromagnetic order was observed with the ferromagnetic transition temperature as high as 70 K.

  • Structural and transport properties of Mn /spl delta/-Doped Gaas layers
    International Conference on Molecular Bean Epitaxy, 1
    Co-Authors: A.m. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    Delta(/spl delta/)-doping of magnetic ions in III-V semiconductors allows locally high concentration of magnetic moments, which can lead to higher ferromagnetic transition temperature as is expected in III-V-based random-alloy magnetic semiconductors. We have recently found that a Mn /spl delta/-Doped Gaas layer only with 0.3 ML Mn concentration showed ferromagnetic ordering when selective p-type doping was introduced. Curie temperature T/sub C/ was found to be as high as 172 K, far above T/sub C/ of random-alloy magnetic semiconductors (e.g. 110 K for GaMnAs. We investigate MBE growth, structural and transport properties of Mn /spl delta/-Doped Gaas and its heterostructures.

Volkan Şenay - One of the best experts on this subject based on the ideXlab platform.

  • Optical and Surface Characteristics of Mg-Doped Gaas Nanocrystalline Thin Film Deposited by Thermionic Vacuum Arc Technique
    Journal of Electronic Materials, 2017
    Co-Authors: Suat Pat, Soner Özen, Volkan Şenay, Şadan Korkmaz
    Abstract:

    Magnesium (Mg) is the most promising p -type dopant for gallium arsenide (Gaas) semiconductor technology. Mg-Doped Gaas nanocrystalline thin film has been deposited at room temperature by the thermionic vacuum arc technique, a rapid deposition method for production of Doped Gaas material. The microstructure and surface and optical properties of the deposited sample were investigated by x-ray diffraction analysis, scanning electron microscopy, energy-dispersive x-ray spectroscopy, atomic force microscopy, ultraviolet–visible spectrophotometry, and interferometry. The crystalline direction of the deposited sample was determined to be (220) plane and (331) plane at 44.53° and 72.30°, respectively. The Mg-Doped Gaas nanocrystalline sample showed high transmittance.

  • Heavily carbon Doped Gaas nanocrystalline thin film deposited by thermionic vacuum arc method
    Journal of Alloys and Compounds, 2016
    Co-Authors: Suat Pat, Şadan Korkmaz, Soner Özen, Volkan Şenay
    Abstract:

    Abstract In this paper, we introduced a new different thin film deposition method for heavily carbon Doped Gaas. Used method is thermionic vacuum arc (TVA) and first used for the carbon doping process. The method is very fast deposition process for the other growth method such as metal organic chemical vapor deposition, molecular beam epitaxy, molecular organic molecular beam epitaxy. The smallest grain size of Gaas and Doped Gaas were obtained by carbon doping process. Mean crystalline size and height of crystalline size were found to be 3.4 nm and 4 nm, respectively. Crystal direction was found to be (022) plane and (024) plane for the sample at 45.322° and 75.060°, respectively. The production process and obtained results show that used methods is very simple, low cost, eco friendly and very fast method for the carbon Doped Gaas.

Satoshi Sugahara - One of the best experts on this subject based on the ideXlab platform.

  • ferromagnetism and high curie temperature in semiconductor heterostructures with mn δ Doped Gaas and p type selective doping
    Physical Review B, 2003
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    The interaction between the magnetic dopants (Mn) and 2-dimensional hole gas (2DHG) in Mn \ensuremath{\delta}-Doped Gaas/Be-Doped $p$-type AlGaas heterostructures, where holes were supplied from the Be-Doped AlGaas to the Mn \ensuremath{\delta}-Doped Gaas, realized ferromagnetic ordering. The Curie temperature ${T}_{\mathrm{C}}$ of the heterostructure prepared with suitable growth conditions was 172 K, highest among the ${T}_{\mathrm{C}}$ values reported in III-V (InAs, Gaas) magnetic semiconductors.

  • mbe growth structural and transport properties of mn δ Doped Gaas layers
    Journal of Crystal Growth, 2003
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    We have grown Mn δ-Doped Gaas layers by molecular beam epitaxy with various Mn sheet concentrations (δMn defined in the monolayer (ML) unit. Structural analyses using cross-sectional transmission electron microscopy and secondary ion mass spectroscopy revealed that when δMnis below I ML, Mn dopants are abruptly confined within 2-3 ML without lattice dislocations and clusters, and also without diffusion and surface segregation. Characterizations on the thermal stability of the doping profiles showed that the profiles retained abruptness even at elevated growth temperature T, = 400°C without diffusion and significant segregation. Strong surface segregation of Mn atoms, lattice dislocations, and MnAs clusters appeared when θMn exceeds 1ML. The transport properties of Mn δ-Doped Gaas layers without and with selectively p-type doping are also presented.

  • Transport properties of Mn δ-Doped Gaas and the effect of selective doping
    Applied Physics Letters, 2002
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    We have grown Mn δ-Doped Gaas layers on Gaas(001) substrates by molecular beam epitaxy. Secondary ion mass spectroscopy and transmission electron microscopy revealed that Mn dopants were abruptly confined. The doping profiles still retained abruptness even at elevated growth temperature up to 400 °C. Mn δ-Doped Gaas samples showed high resistivity at low temperature and did not show a ferromagnetic behavior. However, in a selectively Doped heterostructure (Mn δ-Doped Gaas / Be-Doped AlGaas), where holes were supplied from the Be-Doped AlGaas layer, a ferromagnetic order was observed with the ferromagnetic transition temperature as high as 70 K.

  • Structural and transport properties of Mn /spl delta/-Doped Gaas layers
    International Conference on Molecular Bean Epitaxy, 1
    Co-Authors: A.m. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    Delta(/spl delta/)-doping of magnetic ions in III-V semiconductors allows locally high concentration of magnetic moments, which can lead to higher ferromagnetic transition temperature as is expected in III-V-based random-alloy magnetic semiconductors. We have recently found that a Mn /spl delta/-Doped Gaas layer only with 0.3 ML Mn concentration showed ferromagnetic ordering when selective p-type doping was introduced. Curie temperature T/sub C/ was found to be as high as 172 K, far above T/sub C/ of random-alloy magnetic semiconductors (e.g. 110 K for GaMnAs. We investigate MBE growth, structural and transport properties of Mn /spl delta/-Doped Gaas and its heterostructures.

Ahsan M. Nazmul - One of the best experts on this subject based on the ideXlab platform.

  • Planar Hall Effect and Magnetic Anisotropy in a Mn δ‐Doped Gaas/p‐AlGaas Heterostructure
    IEEJ Transactions on Electrical and Electronic Engineering, 2008
    Co-Authors: Ahsan M. Nazmul, Hung-ta Lin, Shinobu Ohya, Masaaki Tanaka
    Abstract:

    We have studied the planar Hall effect (PHE) in a Mn δ-Doped Gaas-based heterostructure consisting of Mn δ-Doped Gaas and p-type AlGaas. Distinct and large PHE, and a specific in-plane uniaxial magnetic anisotropy were observed below the ferromagnetic transition temperature (TC). This uniaxial in-plane magnetic anisotropy is found dominant over the biaxial cubic anisotropy, and is clearly identified by the angular dependence of PHE. This observation is quantitatively discussed in terms of two models of magnetization reversal; the coherent rotation model and the domain-wall motion model. The model calculation fit to the experimental results make it possible to determine the uniaxial and cubic anisotropy fields and examine the behavior of magnetization reversal. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

  • ferromagnetism and high curie temperature in semiconductor heterostructures with mn δ Doped Gaas and p type selective doping
    Physical Review B, 2003
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    The interaction between the magnetic dopants (Mn) and 2-dimensional hole gas (2DHG) in Mn \ensuremath{\delta}-Doped Gaas/Be-Doped $p$-type AlGaas heterostructures, where holes were supplied from the Be-Doped AlGaas to the Mn \ensuremath{\delta}-Doped Gaas, realized ferromagnetic ordering. The Curie temperature ${T}_{\mathrm{C}}$ of the heterostructure prepared with suitable growth conditions was 172 K, highest among the ${T}_{\mathrm{C}}$ values reported in III-V (InAs, Gaas) magnetic semiconductors.

  • mbe growth structural and transport properties of mn δ Doped Gaas layers
    Journal of Crystal Growth, 2003
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    We have grown Mn δ-Doped Gaas layers by molecular beam epitaxy with various Mn sheet concentrations (δMn defined in the monolayer (ML) unit. Structural analyses using cross-sectional transmission electron microscopy and secondary ion mass spectroscopy revealed that when δMnis below I ML, Mn dopants are abruptly confined within 2-3 ML without lattice dislocations and clusters, and also without diffusion and surface segregation. Characterizations on the thermal stability of the doping profiles showed that the profiles retained abruptness even at elevated growth temperature T, = 400°C without diffusion and significant segregation. Strong surface segregation of Mn atoms, lattice dislocations, and MnAs clusters appeared when θMn exceeds 1ML. The transport properties of Mn δ-Doped Gaas layers without and with selectively p-type doping are also presented.

  • Transport properties of Mn δ-Doped Gaas and the effect of selective doping
    Applied Physics Letters, 2002
    Co-Authors: Ahsan M. Nazmul, Satoshi Sugahara, Masaaki Tanaka
    Abstract:

    We have grown Mn δ-Doped Gaas layers on Gaas(001) substrates by molecular beam epitaxy. Secondary ion mass spectroscopy and transmission electron microscopy revealed that Mn dopants were abruptly confined. The doping profiles still retained abruptness even at elevated growth temperature up to 400 °C. Mn δ-Doped Gaas samples showed high resistivity at low temperature and did not show a ferromagnetic behavior. However, in a selectively Doped heterostructure (Mn δ-Doped Gaas / Be-Doped AlGaas), where holes were supplied from the Be-Doped AlGaas layer, a ferromagnetic order was observed with the ferromagnetic transition temperature as high as 70 K.

Suat Pat - One of the best experts on this subject based on the ideXlab platform.

  • Optical and Surface Characteristics of Mg-Doped Gaas Nanocrystalline Thin Film Deposited by Thermionic Vacuum Arc Technique
    Journal of Electronic Materials, 2017
    Co-Authors: Suat Pat, Soner Özen, Volkan Şenay, Şadan Korkmaz
    Abstract:

    Magnesium (Mg) is the most promising p -type dopant for gallium arsenide (Gaas) semiconductor technology. Mg-Doped Gaas nanocrystalline thin film has been deposited at room temperature by the thermionic vacuum arc technique, a rapid deposition method for production of Doped Gaas material. The microstructure and surface and optical properties of the deposited sample were investigated by x-ray diffraction analysis, scanning electron microscopy, energy-dispersive x-ray spectroscopy, atomic force microscopy, ultraviolet–visible spectrophotometry, and interferometry. The crystalline direction of the deposited sample was determined to be (220) plane and (331) plane at 44.53° and 72.30°, respectively. The Mg-Doped Gaas nanocrystalline sample showed high transmittance.

  • Heavily carbon Doped Gaas nanocrystalline thin film deposited by thermionic vacuum arc method
    Journal of Alloys and Compounds, 2016
    Co-Authors: Suat Pat, Şadan Korkmaz, Soner Özen, Volkan Şenay
    Abstract:

    Abstract In this paper, we introduced a new different thin film deposition method for heavily carbon Doped Gaas. Used method is thermionic vacuum arc (TVA) and first used for the carbon doping process. The method is very fast deposition process for the other growth method such as metal organic chemical vapor deposition, molecular beam epitaxy, molecular organic molecular beam epitaxy. The smallest grain size of Gaas and Doped Gaas were obtained by carbon doping process. Mean crystalline size and height of crystalline size were found to be 3.4 nm and 4 nm, respectively. Crystal direction was found to be (022) plane and (024) plane for the sample at 45.322° and 75.060°, respectively. The production process and obtained results show that used methods is very simple, low cost, eco friendly and very fast method for the carbon Doped Gaas.