Muhammad Abdi - Academia.edu (original) (raw)

Papers by Muhammad Abdi

Materials Science and Engineering B-advanced Functional Solid-state Materials, 2005

In the attempt to realize quantum devices based on a resonant tunneling effect through Si/SiO2 an... more In the attempt to realize quantum devices based on a resonant tunneling effect through Si/SiO2 and emitting a red light at a key 0.644 μm wavelength, we have modeled SiO2/Si/SiO2 double barriers embedded between two n-doped Si layers. To study the quantum confinement in Si QW and obtain the potential shape, we have solved a set of coupled Schrödinger–Poisson equations self-consistently. The effects of Si well thickness on quantum confinement of electrons and heavy-holes levels are presented. The fundamental energy transition and oscillator strength are also examined as a function of well width. A blue shift of the emission energy is observed, when the thickness of the Si well is reduced. The desired red light at a key 0.644 μm wavelength is obtained with an acceptable recombination efficiency given by transition oscillator strength. The effect of an applied electric field has been investigated for this red emission.

Materials Science in Semiconductor Processing, 2006

Silicon-based devices are currently the most attractive group because they are functioning at roo... more Silicon-based devices are currently the most attractive group because they are functioning at room temperature and can be easily integrated into conventional silicon microelectronics. There are many models and simulation programs available to compute CV curves with quantum correction [Choi C-H, Wu Y, Goo JS, Yu Z, Dutton RW. IEEE Trans on Electron Devi 2000; 47(10): 1843; Croci S, Plossu C, Burignat S. J Mater Sci Mater Electron 2003; 14: 311; Soliman L, Duval E, Benzohra M, Lheurette E, Ketata K, Ketata M. Mater Sci Semicond Process 2001; 4: 163]. This work deals with the simulation of electron transfer through SiO2 barrier of metal–oxide–semiconductor structure (MOS). The carrier density is given by a self consistent resolution of Schrödinger and Poisson equations and then the MOS capacitance is deduced and compared with results available in literature. As it is well known, the MOS capacitance–voltage profiling provides a simple determination of structure parameters. The extracted tunnel oxide thickness and substrate doping are compared with those used in the simulation. For the purpose to investigate the electron tunnelling through the barrier, we have used the transfer matrix approach. Using I–V simulations, we have shown that the traps in SiO2 matrix have a drastic influence on electron tunnelling through the barrier. The trap-assisted contribution to the tunnelling current is included in many models [Maserjian J, Zamani N. J Appl Phys 1982; 53(1): 559; Houssa M, Stesmans A, Heyns MM. Semicond Sci Technol 2001; 16: 427; Aziz A, Kassmi K, Kassmi Ka, Olivie F. Semicond Sci Technol 2004; 19: 877; Wu You-Lin, Lin Shi-Tin. IEEE Trans Dev Mater Reliab 2006; 6(1): 75; Larcher L. IEEE Trans Electron Dev 2003; 50(5): 1246]; this is the basis for the interpretation of stress induced leakage current (SILC) and breakdown events. Memory effect becomes typical for this structure. We have studied the I–V dependence with trap parameters.

Using a technology where pollution is regarded as by-product of industry's activity and applied i... more Using a technology where pollution is regarded as by-product of industry's activity and applied in a simple setup of Heckscher-Ohlin-Copeland-Taylor model,

Journal of Natural Medicines, 2011

The methanol extracts of 20 selected medicinal plants were investigated for their effects on the ... more The methanol extracts of 20 selected medicinal plants were investigated for their effects on the respiratory burst of human whole blood, isolated human polymorphonuclear leukocytes (PMNs) and isolated mice macrophages using a luminol/lucigenin-based chemiluminescence assay. We also tested the effect of the extracts on chemotactic migration of PMNs using the Boyden chamber technique. The extracts of Curcuma domestica L., Phyllanthus amarus Schum & Thonn and C. xanthorrhiza Roxb. were the samples producing the strongest oxidative burst of PMNs with luminol-based chemiluminescence, with IC50 values ranging from 0.5 to 0.7 μg/ml. For macrophage cells, the extracts which showed strong suppressive activity for luminol-based chemiluminescence were C. xanthorrhiza and Garcinia mangostana L. Among the extracts studied, C. mangga Valton & Vazsjip, Piper nigrum L. and Labisia pumila var. alata showed strong inhibitory activity on lucigenin-amplified oxidative burst of PMNs, with IC50 values ranging from 0.9 to 1.5 μg/ml. The extracts of Zingiber officinale Rosc., Alpinia galangal (L.) Willd and Averrhoa bilimbi Linn showed strong inhibition on the chemotaxic migration of cells, with IC50 values comparable to that of ibuprofen (1.5 μg/ml). The results suggest that some of these plants were able to modulate the innate immune response of phagocytes at different steps, emphasizing their potential as a source of new immunomodulatory agents.

Journal of Alloys and Compounds, 2011

Due to the large variety of properties offered by the telluride binaries CdTe, ZnTe, MgTe, HgTe a... more Due to the large variety of properties offered by the telluride binaries CdTe, ZnTe, MgTe, HgTe and MnTe as well as their mixed ternary alloys, an accurate knowledge of their electronic band parameters is crucial. These materials have been extensively studied but, some points bearing on several properties have never previously reported or are still not clear. In this paper, we report results on the conduction and valence band offsets of the pseudo-morphically strained Cd1−xXxTe layer on relaxed Cd1−yXyTe substrate, X = Zn, Hg, Mg and Mn. Based on the Van Der Walle model, calculations have been performed for the all range of material and substrate 0 ≤ x,y ≤ 1. These discontinuities have not yet calculated for X = Mg, Mn or Hg in the all range 0 ≤ x,y ≤ 1. For the CdMnTe diluted magnetic semiconductor which we focus more interest due to its considerable current interest for applications, calculations have been done without and with correction taking into account magnetic effect of magnesium ions Mn2+. It is found that the introduction of only a few percent of Mn into CdTe provides a unique opportunity to combine two important fields in physics, semiconductivity and magnetism. We can take advantage both of possibility of applications in solid-state lasers and exceptional magnetic properties offered by this magnetic diluted semiconductor.This study presents important quantities that are required to model quantum structures and offers a fast and inexpensive way to check device designs and processes.► The conduction and valence band offsets of the pseudo-morphically strained Cd1−xXxTe layer on relaxed Cd1−yXyTe substrate, are investigated for X = Zn, Mg, Hg and Mn in the entire range 0 ≤ x,y ≤ 1. ► For Cd1−xMnxTe diluted magnetic semiconductors, the exchange interactions are determined in the order to take into account magnetic effect. ► The conduction and valence band offsets of Cd1−xMnxTe/CdTe interface are calculated in the whole range of Mn composition x and for magnetic field values equal to 0 and 5 T.

Primary as well secondary sources of the Rice producing countries, and data were analysis by usin... more Primary as well secondary sources of the Rice producing countries, and data were analysis by using SPSS-18 version, A structural questionnaire was developed for reliability and validity of the data. It was revealed that from the last five years there is no visible impact on ...

Materials Science in Semiconductor Processing, 2006

SiGe/Si resonant tunneling diodes (RTDs) grown on relaxed n-Ge0.3Si0.7 virtual substrates are att... more SiGe/Si resonant tunneling diodes (RTDs) grown on relaxed n-Ge0.3Si0.7 virtual substrates are attractive devices for low-power/high-frequency applications compatible with Si-CMOS technology. With the intention to improve the performances of n-type RTDs build-on Si0.4Ge0.6/Si/Si0.4Ge0.6 double barriers, we consider graded Si1−xGex (x=0.3→0.0) spacers (triangular quantum wells) for injection and collection of electrons. Graded layer composition, implanted for the lattice mismatch growth of many semiconductors, has offered significant improvement in the epilayer quality and hence was used for many advanced electronic and optoelectronic applications. The modeled design is aimed to further reduce the voltage at which peak-current density is achieved and to increase the current-peak to valley ratio. We report a numerical solution of the conduction-band profile by solving self-consistently Schrödinger and Poisson equations without and with an applied electric field. An analysis of the Stark effect on electronic levels is made. Two main features have been extrapolated: (i) a charge transfer can occur due to the tunneling effect, and this charge transfer tends to saturate as the applied electric field increases; (ii) the middle quantum well is populated compared with common RTD having an abrupt Si spacer (squared quantum wells).

PLOS One, 2011

Human-orangutan conflict and hunting are thought to pose a serious threat to orangutan existence ... more Human-orangutan conflict and hunting are thought to pose a serious threat to orangutan existence in Kalimantan, the Indonesian part of Borneo. No data existed prior to the present study to substantiate these threats. We investigated the rates, spatial distribution and causes of conflict and hunting through an interview-based survey in the orangutan's range in Kalimantan, Indonesia. Between April 2008 and September 2009, we interviewed 6983 respondents in 687 villages to obtain socio-economic information, assess knowledge of local wildlife in general and orangutan encounters specifically, and to query respondents about their knowledge on orangutan conflicts and killing, and relevant laws. This survey revealed estimated killing rates of between 750 and 1800 animals killed in the last year, and between 1950 and 3100 animals killed per year on average within the lifetime of the survey respondents. These killing rates are higher than previously thought and are high enough to pose a serious threat to the continued existence of orangutans in Kalimantan. Importantly, the study contributes to our understanding of the spatial variation in threats, and the underlying causes of those threats, which can be used to facilitate the development of targeted conservation management.

Journal of Cognitive Neuroscience, 2010

The ability to make categorical decisions and interpret sensory experiences is critical for survi... more The ability to make categorical decisions and interpret sensory experiences is critical for survival and interactions across the lifespan. However, little is known about the human brain mechanisms that mediate the learning and representation of visual categories in aging. Here we combine behavioral measurements and fMRI measurements to investigate the neural processes that mediate flexible category learning in the aging human brain. Our findings show that training changes the decision criterion (i.e., categorical boundary) that young and older observers use for making categorical judgments. Comparing the behavioral choices of human observers with those of a pattern classifier based upon multivoxel fMRI signals, we demonstrate learning-dependent changes in similar cortical areas for young and older adults. In particular, we show that neural signals in occipito-temporal and posterior parietal regions change through learning to reflect the perceived visual categories. Information in these areas about the perceived visual categories is preserved in aging, whereas information content is compromised in more anterior parietal and frontal circuits. Thus, these findings provide novel evidence for flexible category learning in aging that shapes the neural representations of visual categories to reflect the observers' behavioral judgments.

Materials Science and Engineering B-advanced Functional Solid-state Materials, 2005

In the attempt to realize quantum devices based on a resonant tunneling effect through Si/SiO2 an... more In the attempt to realize quantum devices based on a resonant tunneling effect through Si/SiO2 and emitting a red light at a key 0.644 μm wavelength, we have modeled SiO2/Si/SiO2 double barriers embedded between two n-doped Si layers. To study the quantum confinement in Si QW and obtain the potential shape, we have solved a set of coupled Schrödinger–Poisson equations self-consistently. The effects of Si well thickness on quantum confinement of electrons and heavy-holes levels are presented. The fundamental energy transition and oscillator strength are also examined as a function of well width. A blue shift of the emission energy is observed, when the thickness of the Si well is reduced. The desired red light at a key 0.644 μm wavelength is obtained with an acceptable recombination efficiency given by transition oscillator strength. The effect of an applied electric field has been investigated for this red emission.

Materials Science in Semiconductor Processing, 2006

Silicon-based devices are currently the most attractive group because they are functioning at roo... more Silicon-based devices are currently the most attractive group because they are functioning at room temperature and can be easily integrated into conventional silicon microelectronics. There are many models and simulation programs available to compute CV curves with quantum correction [Choi C-H, Wu Y, Goo JS, Yu Z, Dutton RW. IEEE Trans on Electron Devi 2000; 47(10): 1843; Croci S, Plossu C, Burignat S. J Mater Sci Mater Electron 2003; 14: 311; Soliman L, Duval E, Benzohra M, Lheurette E, Ketata K, Ketata M. Mater Sci Semicond Process 2001; 4: 163]. This work deals with the simulation of electron transfer through SiO2 barrier of metal–oxide–semiconductor structure (MOS). The carrier density is given by a self consistent resolution of Schrödinger and Poisson equations and then the MOS capacitance is deduced and compared with results available in literature. As it is well known, the MOS capacitance–voltage profiling provides a simple determination of structure parameters. The extracted tunnel oxide thickness and substrate doping are compared with those used in the simulation. For the purpose to investigate the electron tunnelling through the barrier, we have used the transfer matrix approach. Using I–V simulations, we have shown that the traps in SiO2 matrix have a drastic influence on electron tunnelling through the barrier. The trap-assisted contribution to the tunnelling current is included in many models [Maserjian J, Zamani N. J Appl Phys 1982; 53(1): 559; Houssa M, Stesmans A, Heyns MM. Semicond Sci Technol 2001; 16: 427; Aziz A, Kassmi K, Kassmi Ka, Olivie F. Semicond Sci Technol 2004; 19: 877; Wu You-Lin, Lin Shi-Tin. IEEE Trans Dev Mater Reliab 2006; 6(1): 75; Larcher L. IEEE Trans Electron Dev 2003; 50(5): 1246]; this is the basis for the interpretation of stress induced leakage current (SILC) and breakdown events. Memory effect becomes typical for this structure. We have studied the I–V dependence with trap parameters.

Using a technology where pollution is regarded as by-product of industry's activity and applied i... more Using a technology where pollution is regarded as by-product of industry's activity and applied in a simple setup of Heckscher-Ohlin-Copeland-Taylor model,

Journal of Natural Medicines, 2011

The methanol extracts of 20 selected medicinal plants were investigated for their effects on the ... more The methanol extracts of 20 selected medicinal plants were investigated for their effects on the respiratory burst of human whole blood, isolated human polymorphonuclear leukocytes (PMNs) and isolated mice macrophages using a luminol/lucigenin-based chemiluminescence assay. We also tested the effect of the extracts on chemotactic migration of PMNs using the Boyden chamber technique. The extracts of Curcuma domestica L., Phyllanthus amarus Schum & Thonn and C. xanthorrhiza Roxb. were the samples producing the strongest oxidative burst of PMNs with luminol-based chemiluminescence, with IC50 values ranging from 0.5 to 0.7 μg/ml. For macrophage cells, the extracts which showed strong suppressive activity for luminol-based chemiluminescence were C. xanthorrhiza and Garcinia mangostana L. Among the extracts studied, C. mangga Valton & Vazsjip, Piper nigrum L. and Labisia pumila var. alata showed strong inhibitory activity on lucigenin-amplified oxidative burst of PMNs, with IC50 values ranging from 0.9 to 1.5 μg/ml. The extracts of Zingiber officinale Rosc., Alpinia galangal (L.) Willd and Averrhoa bilimbi Linn showed strong inhibition on the chemotaxic migration of cells, with IC50 values comparable to that of ibuprofen (1.5 μg/ml). The results suggest that some of these plants were able to modulate the innate immune response of phagocytes at different steps, emphasizing their potential as a source of new immunomodulatory agents.

Journal of Alloys and Compounds, 2011

Due to the large variety of properties offered by the telluride binaries CdTe, ZnTe, MgTe, HgTe a... more Due to the large variety of properties offered by the telluride binaries CdTe, ZnTe, MgTe, HgTe and MnTe as well as their mixed ternary alloys, an accurate knowledge of their electronic band parameters is crucial. These materials have been extensively studied but, some points bearing on several properties have never previously reported or are still not clear. In this paper, we report results on the conduction and valence band offsets of the pseudo-morphically strained Cd1−xXxTe layer on relaxed Cd1−yXyTe substrate, X = Zn, Hg, Mg and Mn. Based on the Van Der Walle model, calculations have been performed for the all range of material and substrate 0 ≤ x,y ≤ 1. These discontinuities have not yet calculated for X = Mg, Mn or Hg in the all range 0 ≤ x,y ≤ 1. For the CdMnTe diluted magnetic semiconductor which we focus more interest due to its considerable current interest for applications, calculations have been done without and with correction taking into account magnetic effect of magnesium ions Mn2+. It is found that the introduction of only a few percent of Mn into CdTe provides a unique opportunity to combine two important fields in physics, semiconductivity and magnetism. We can take advantage both of possibility of applications in solid-state lasers and exceptional magnetic properties offered by this magnetic diluted semiconductor.This study presents important quantities that are required to model quantum structures and offers a fast and inexpensive way to check device designs and processes.► The conduction and valence band offsets of the pseudo-morphically strained Cd1−xXxTe layer on relaxed Cd1−yXyTe substrate, are investigated for X = Zn, Mg, Hg and Mn in the entire range 0 ≤ x,y ≤ 1. ► For Cd1−xMnxTe diluted magnetic semiconductors, the exchange interactions are determined in the order to take into account magnetic effect. ► The conduction and valence band offsets of Cd1−xMnxTe/CdTe interface are calculated in the whole range of Mn composition x and for magnetic field values equal to 0 and 5 T.

Primary as well secondary sources of the Rice producing countries, and data were analysis by usin... more Primary as well secondary sources of the Rice producing countries, and data were analysis by using SPSS-18 version, A structural questionnaire was developed for reliability and validity of the data. It was revealed that from the last five years there is no visible impact on ...

Materials Science in Semiconductor Processing, 2006

SiGe/Si resonant tunneling diodes (RTDs) grown on relaxed n-Ge0.3Si0.7 virtual substrates are att... more SiGe/Si resonant tunneling diodes (RTDs) grown on relaxed n-Ge0.3Si0.7 virtual substrates are attractive devices for low-power/high-frequency applications compatible with Si-CMOS technology. With the intention to improve the performances of n-type RTDs build-on Si0.4Ge0.6/Si/Si0.4Ge0.6 double barriers, we consider graded Si1−xGex (x=0.3→0.0) spacers (triangular quantum wells) for injection and collection of electrons. Graded layer composition, implanted for the lattice mismatch growth of many semiconductors, has offered significant improvement in the epilayer quality and hence was used for many advanced electronic and optoelectronic applications. The modeled design is aimed to further reduce the voltage at which peak-current density is achieved and to increase the current-peak to valley ratio. We report a numerical solution of the conduction-band profile by solving self-consistently Schrödinger and Poisson equations without and with an applied electric field. An analysis of the Stark effect on electronic levels is made. Two main features have been extrapolated: (i) a charge transfer can occur due to the tunneling effect, and this charge transfer tends to saturate as the applied electric field increases; (ii) the middle quantum well is populated compared with common RTD having an abrupt Si spacer (squared quantum wells).

PLOS One, 2011

Human-orangutan conflict and hunting are thought to pose a serious threat to orangutan existence ... more Human-orangutan conflict and hunting are thought to pose a serious threat to orangutan existence in Kalimantan, the Indonesian part of Borneo. No data existed prior to the present study to substantiate these threats. We investigated the rates, spatial distribution and causes of conflict and hunting through an interview-based survey in the orangutan's range in Kalimantan, Indonesia. Between April 2008 and September 2009, we interviewed 6983 respondents in 687 villages to obtain socio-economic information, assess knowledge of local wildlife in general and orangutan encounters specifically, and to query respondents about their knowledge on orangutan conflicts and killing, and relevant laws. This survey revealed estimated killing rates of between 750 and 1800 animals killed in the last year, and between 1950 and 3100 animals killed per year on average within the lifetime of the survey respondents. These killing rates are higher than previously thought and are high enough to pose a serious threat to the continued existence of orangutans in Kalimantan. Importantly, the study contributes to our understanding of the spatial variation in threats, and the underlying causes of those threats, which can be used to facilitate the development of targeted conservation management.

Journal of Cognitive Neuroscience, 2010

The ability to make categorical decisions and interpret sensory experiences is critical for survi... more The ability to make categorical decisions and interpret sensory experiences is critical for survival and interactions across the lifespan. However, little is known about the human brain mechanisms that mediate the learning and representation of visual categories in aging. Here we combine behavioral measurements and fMRI measurements to investigate the neural processes that mediate flexible category learning in the aging human brain. Our findings show that training changes the decision criterion (i.e., categorical boundary) that young and older observers use for making categorical judgments. Comparing the behavioral choices of human observers with those of a pattern classifier based upon multivoxel fMRI signals, we demonstrate learning-dependent changes in similar cortical areas for young and older adults. In particular, we show that neural signals in occipito-temporal and posterior parietal regions change through learning to reflect the perceived visual categories. Information in these areas about the perceived visual categories is preserved in aging, whereas information content is compromised in more anterior parietal and frontal circuits. Thus, these findings provide novel evidence for flexible category learning in aging that shapes the neural representations of visual categories to reflect the observers' behavioral judgments.