PHẠM HAI PHONG - Academia.edu (original) (raw)
Papers by PHẠM HAI PHONG
Physical Review B, 2004
We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si/ SiGe ... more We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si/ SiGe p-channel heterostructures. Our theory must not be based on the unclear concept of interface impurity charges assumed in the previous calculations, but takes adequate account of the random deformation potential and random piezoelectric field. These appear as effects arising from both lattice mismatch and interface roughness. It is proved that deformation potential scattering may be predominant over the well-known scattering mechanisms such as background doping, alloy disorder, and surface roughness for a Ge content x տ 0.2, while piezoelectric scattering is comparable thereto for x տ 0.4. Our theory turns out to be successful in providing a good quantitative explanation of recent experimental findings not only about the low value of the hole mobility but also its dependence on carrier density as well as its decrease with Ge content.
Physical Review B, 2005
We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in... more We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in wurtzite group-III-nitride heterostructures, e.g., AlGaN/ GaN, taking adequate account of the roughness-induced scattering mechanisms and the effect due to sheet polarization charges. The squeeze of the electron distribution in the quantum well by positive piezoelectric and spontaneous polarization-induced charges on the interface is calculated in an analytic form. Thus, we obtained simple expressions describing the squeeze-related enhancement of the 2DEG screening and the unscreened potentials for different scattering sources. Altogether, their screened potentials may be strongly enhanced, so that the 2DEG mobility may be remarkably reduced by sheet polarization charges. Moreover, we proved that the roughness-induced piezoelectric charges and the roughnessinduced deformation potential exhibit new important scattering mechanisms governing the 2DEG transport in wurtzite III-nitride heterostructures. The partial 2DEG mobilities limited by them may be of the order of or less than 10 3 cm 2 / V s. Our theory turns out to be successful in the quantitative explanation of recent experimental data about the high-density 2DEG mobility, e.g., its nonmonotonic dependence on carrier density and its enhancement in the double heterostructure, which have not been understood starting merely from the conventional scattering mechanisms.
Physical Review B, 2004
We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si∕SiGe p... more We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si∕SiGe p -channel heterostructures. Our theory must not be based on the unclear concept of interface impurity charges assumed in the previous calculations, but takes adequate account of the ...
Physical Review B, 2005
We present a theoretical study of the disorder effect due to interface roughness on piezoelectric... more We present a theoretical study of the disorder effect due to interface roughness on piezoelectricity in wurtzite group-III-nitride heterostructures, eg, AlGaN∕GaN . We have proved that interface roughness gives rise to random nonuniform fluctuations in the piezoelectric polarization. ...
Physical Review B, 2005
We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in... more We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in wurtzite group-III-nitride heterostructures, e.g., AlGaN/ GaN, taking adequate account of the roughness-induced scattering mechanisms and the effect due to sheet polarization charges. The squeeze of the electron distribution in the quantum well by positive piezoelectric and spontaneous polarization-induced charges on the interface is calculated in an analytic form. Thus, we obtained simple expressions describing the squeeze-related enhancement of the 2DEG screening and the unscreened potentials for different scattering sources. Altogether, their screened potentials may be strongly enhanced, so that the 2DEG mobility may be remarkably reduced by sheet polarization charges. Moreover, we proved that the roughness-induced piezoelectric charges and the roughnessinduced deformation potential exhibit new important scattering mechanisms governing the 2DEG transport in wurtzite III-nitride heterostructures. The partial 2DEG mobilities limited by them may be of the order of or less than 10 3 cm 2 / V s. Our theory turns out to be successful in the quantitative explanation of recent experimental data about the high-density 2DEG mobility, e.g., its nonmonotonic dependence on carrier density and its enhancement in the double heterostructure, which have not been understood starting merely from the conventional scattering mechanisms.
Physical Review B, 2005
We present a theoretical study of the disorder effect due to interface roughness on piezoelectric... more We present a theoretical study of the disorder effect due to interface roughness on piezoelectricity in wurtzite group-III-nitride heterostructures, eg, AlGaN∕GaN . We have proved that interface roughness gives rise to random nonuniform fluctuations in the piezoelectric polarization. ...
Journal of Computer Science and Cybernetics, 2012
Journal of Computer Science and Cybernetics. Open Journal Systems. Journal Help. User Username, P... more Journal of Computer Science and Cybernetics. Open Journal Systems. Journal Help. User Username, Password, Remember me. Language English. ...
Journal of Computer Science and Cybernetics, 2014
Advances in Intelligent Systems and Computing, 2014
Proceedings of the 2010 Symposium on Information and Communication Technology - SoICT '10, 2010
Protecting data by passwords in documents such as DOC, PDF or RAR, ZIP archives has been demonstr... more Protecting data by passwords in documents such as DOC, PDF or RAR, ZIP archives has been demonstrated to be weak under dictionary attacks. Time for recovering the passwords of such documents mainly depends on two factors: the size of the password search space and the computing power of the underline system. In this paper, we present an approach using modern multi-core graphic processing units (GPUs) as computing devices for finding lost passwords of ZIP archives. The combination of GPU's extremely high computing power and the state-of-the-art password structure analysis methods would bring us a feasible solution for recovering ZIP file password. We first apply password generation rules in generating a reasonable password space, and then use GPUs for exhaustively verifying every password in the space. The experimental results have shown that the password verification speed increases about from 48 to 170 times (depends on the number of GPUs) compared to sequential execution on the Intel Core 2 Quad Q8400 2.66 Ghz. These results have demonstrated the potential applicability of GPUs in this cryptanalysis field.
Physical Review B, 2004
We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si/ SiGe ... more We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si/ SiGe p-channel heterostructures. Our theory must not be based on the unclear concept of interface impurity charges assumed in the previous calculations, but takes adequate account of the random deformation potential and random piezoelectric field. These appear as effects arising from both lattice mismatch and interface roughness. It is proved that deformation potential scattering may be predominant over the well-known scattering mechanisms such as background doping, alloy disorder, and surface roughness for a Ge content x տ 0.2, while piezoelectric scattering is comparable thereto for x տ 0.4. Our theory turns out to be successful in providing a good quantitative explanation of recent experimental findings not only about the low value of the hole mobility but also its dependence on carrier density as well as its decrease with Ge content.
Physical Review B, 2005
We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in... more We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in wurtzite group-III-nitride heterostructures, e.g., AlGaN/ GaN, taking adequate account of the roughness-induced scattering mechanisms and the effect due to sheet polarization charges. The squeeze of the electron distribution in the quantum well by positive piezoelectric and spontaneous polarization-induced charges on the interface is calculated in an analytic form. Thus, we obtained simple expressions describing the squeeze-related enhancement of the 2DEG screening and the unscreened potentials for different scattering sources. Altogether, their screened potentials may be strongly enhanced, so that the 2DEG mobility may be remarkably reduced by sheet polarization charges. Moreover, we proved that the roughness-induced piezoelectric charges and the roughnessinduced deformation potential exhibit new important scattering mechanisms governing the 2DEG transport in wurtzite III-nitride heterostructures. The partial 2DEG mobilities limited by them may be of the order of or less than 10 3 cm 2 / V s. Our theory turns out to be successful in the quantitative explanation of recent experimental data about the high-density 2DEG mobility, e.g., its nonmonotonic dependence on carrier density and its enhancement in the double heterostructure, which have not been understood starting merely from the conventional scattering mechanisms.
Physical Review B, 2004
We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si∕SiGe p... more We present a theory of the low-temperature mobility of holes in strained SiGe layers of Si∕SiGe p -channel heterostructures. Our theory must not be based on the unclear concept of interface impurity charges assumed in the previous calculations, but takes adequate account of the ...
Physical Review B, 2005
We present a theoretical study of the disorder effect due to interface roughness on piezoelectric... more We present a theoretical study of the disorder effect due to interface roughness on piezoelectricity in wurtzite group-III-nitride heterostructures, eg, AlGaN∕GaN . We have proved that interface roughness gives rise to random nonuniform fluctuations in the piezoelectric polarization. ...
Physical Review B, 2005
We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in... more We present a theory of the low-temperature mobility of the two-dimensional electron gas ͑2DEG͒ in wurtzite group-III-nitride heterostructures, e.g., AlGaN/ GaN, taking adequate account of the roughness-induced scattering mechanisms and the effect due to sheet polarization charges. The squeeze of the electron distribution in the quantum well by positive piezoelectric and spontaneous polarization-induced charges on the interface is calculated in an analytic form. Thus, we obtained simple expressions describing the squeeze-related enhancement of the 2DEG screening and the unscreened potentials for different scattering sources. Altogether, their screened potentials may be strongly enhanced, so that the 2DEG mobility may be remarkably reduced by sheet polarization charges. Moreover, we proved that the roughness-induced piezoelectric charges and the roughnessinduced deformation potential exhibit new important scattering mechanisms governing the 2DEG transport in wurtzite III-nitride heterostructures. The partial 2DEG mobilities limited by them may be of the order of or less than 10 3 cm 2 / V s. Our theory turns out to be successful in the quantitative explanation of recent experimental data about the high-density 2DEG mobility, e.g., its nonmonotonic dependence on carrier density and its enhancement in the double heterostructure, which have not been understood starting merely from the conventional scattering mechanisms.
Physical Review B, 2005
We present a theoretical study of the disorder effect due to interface roughness on piezoelectric... more We present a theoretical study of the disorder effect due to interface roughness on piezoelectricity in wurtzite group-III-nitride heterostructures, eg, AlGaN∕GaN . We have proved that interface roughness gives rise to random nonuniform fluctuations in the piezoelectric polarization. ...
Journal of Computer Science and Cybernetics, 2012
Journal of Computer Science and Cybernetics. Open Journal Systems. Journal Help. User Username, P... more Journal of Computer Science and Cybernetics. Open Journal Systems. Journal Help. User Username, Password, Remember me. Language English. ...
Journal of Computer Science and Cybernetics, 2014
Advances in Intelligent Systems and Computing, 2014
Proceedings of the 2010 Symposium on Information and Communication Technology - SoICT '10, 2010
Protecting data by passwords in documents such as DOC, PDF or RAR, ZIP archives has been demonstr... more Protecting data by passwords in documents such as DOC, PDF or RAR, ZIP archives has been demonstrated to be weak under dictionary attacks. Time for recovering the passwords of such documents mainly depends on two factors: the size of the password search space and the computing power of the underline system. In this paper, we present an approach using modern multi-core graphic processing units (GPUs) as computing devices for finding lost passwords of ZIP archives. The combination of GPU's extremely high computing power and the state-of-the-art password structure analysis methods would bring us a feasible solution for recovering ZIP file password. We first apply password generation rules in generating a reasonable password space, and then use GPUs for exhaustively verifying every password in the space. The experimental results have shown that the password verification speed increases about from 48 to 170 times (depends on the number of GPUs) compared to sequential execution on the Intel Core 2 Quad Q8400 2.66 Ghz. These results have demonstrated the potential applicability of GPUs in this cryptanalysis field.