B NOOR MOHAMMAD - Academia.edu (original) (raw)

Papers by B NOOR MOHAMMAD

Zenodo (CERN European Organization for Nuclear Research), Dec 31, 1984

Philosophical Magazine B, 2001

An improved model for trap-assisted recombination taking into account Shockley± Read± Hall recomb... more An improved model for trap-assisted recombination taking into account Shockley± Read± Hall recombination, trap-assisted Auger (TAA) recombination and tunnelling due to the electric ® eld has been developed. To our knowledge, this is the most general model for trap-assisted recombination reported in the literature. The model describes the weak temperature dependence of the recombination rate for the bulk, but the strong temperature dependence of the recombination rate for the depletion region. The TAA process contributes weakly to the net recombination unless the doping is very heavy. However, it contributes heavily to recombination in the junction depletion region even at relatively lower doping levels. The calculated minority-carrier lifetime and diOE usion length closely correspond to the average experimental data.

Philosophical Magazine B, 1996

Philosophical Magazine B, 1997

Abstract Anomalous doping characteristics of III-V nitrides are explained on the basis of experim... more Abstract Anomalous doping characteristics of III-V nitrides are explained on the basis of experimental methods. To our knowledge, this is the first successful experimental attempt to address the doping difficulties with the p-and n-type Iii-V nitrides. GaN is used as the test ...

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 2004

A novel two-step surface treatment method has been developed to realize low resistance nonalloyed... more A novel two-step surface treatment method has been developed to realize low resistance nonalloyed ohmic contact to n-type GaN doped with Si to 6×1017 cm−3. The removal of native oxide (oxides and hydroxides) formed on GaN surface is crucial for successful creation of nonalloyed low resistance ohmic contact. In the case of GaN, plasma etching of the material surface prior to metal deposition holds promise for developing such nonalloyed ohmic contacts. In this article, the effects of the postetch chemical treatment of the n-type GaN surface on the Ti based nonalloyed contact performance have been investigated. Contacts on samples without reactive ion etching (RIE) showed Schottky behavior. However, contacts on samples with 15 s of RIE using Cl2 showed ohmic behavior. The contact resistivity of this contact reached to ρs=1.2×10−3 Ω cm2. Treating the RIE etched sample in boiling aqua regia for 5 min yielded a contact resistivity on the order of 3.6×10−4 Ω cm2. Dramatic improvement in cu...

Photodiagnosis and Photodynamic Therapy, 2015

Study of low doses Cisplatin synergistic effect on photodynamic outcome of aluminum phythalocyani... more Study of low doses Cisplatin synergistic effect on photodynamic outcome of aluminum phythalocyanine on soft tissue sarcoma (RD) cell line

Physica B: Condensed Matter, 2013

ABSTRACT The structural, electronic and optical properties of IIA-VIA compounds are performed, by... more ABSTRACT The structural, electronic and optical properties of IIA-VIA compounds are performed, by using the full-potential linearized augmented plan wave (FP-LAPW) method within DFT, by using the (PBEsol-GGA 2008) version. We have compared the modified Becke-Johnson (mBJ) potential to LDA, GGA and EV-GGA approximations. The IIA-VIA compounds have rock salt structure (B1) and zinc-blend structure (B3). The results obtained for band structure using mBJ show a significant improvement over previous theoretical work and give closer values to the experimental results. The bandgaps less than 3.1 eV are used in the visible light devices applications, while those with bandgaps bigger than 3.1 eV, used in UV devices applications. Optical parameters, like the dielectric constant, refractive indices, reflectivity, optical conductivity and absorption coefficient are calculated and analyzed. Refractive index lesser than unity (vg=c/n) shows that the group velocity of the incident radiation is greater than the speed of light.

Solid-State Electronics, 2001

Small-signal bipolar junction transistor (BJT) amplifiers, including common-emitter (C-E), common... more Small-signal bipolar junction transistor (BJT) amplifiers, including common-emitter (C-E), common-base, and common-collector amplifiers, are the basic building blocks of many analog integrated circuits. An experimental investigation of the physical analysis of the frequency response and related parameters of these amplifiers have been performed in some details. The analysis uncovers fundamental reasons underlying the frequency response of the amplifiers. It indicates

Solid-State Electronics, 2002

Cubic boron nitride (c-BN), if properly developed, can be a very promising material for electroni... more Cubic boron nitride (c-BN), if properly developed, can be a very promising material for electronic applications, such as ultraviolet (UV) detectors and UV light emitting diodes operable at wavelengths in the deep UV regime. Its energy bandgap is favorable also for field-effect transistors for ...

Solid-State Electronics, 1992

Abstract An improved analytical formula for the drift velocities of hot electrons and holes in se... more Abstract An improved analytical formula for the drift velocities of hot electrons and holes in semiconductors is suggested. Calculated results from the model show striking agreements with the available experiments. Unlike the earlier ones, the model predicts the low-field ...

Solid-State Electronics, 1990

ABSTRACT

Molecular Physics, 1976

The virial equation of state is generally written in the form ... PV/RT = 1 + B( T)/V + C( T)/V 2... more The virial equation of state is generally written in the form ... PV/RT = 1 + B( T)/V + C( T)/V 2 +..., ... B (~)(T) = B e (i)(T) + Bq (~)(T). ... Here Bc(i)(T) is the classical second virial coefficient and Bq(i)(T) is a relatively small correction term due to quantum effects. For atoms or ...

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 2007

A model describing the dielectrophoretic alignment of gallium nitride nanowires suspended in a so... more A model describing the dielectrophoretic alignment of gallium nitride nanowires suspended in a solvent is presented here. The variations in the dielectrophoretic forces experienced by nanowires in different dispersing solvents have been calculated. It is shown that the relative sizes of the nanowires with respect to the spherical microparticles play a major role in the dielectrophoretic forces experienced by them.

Journal of Theoretical Biology, 1983

The mutagenic potencies of 30 polycyclic aromatic hydrocarbons, (PAHs) were quantitatively relate... more The mutagenic potencies of 30 polycyclic aromatic hydrocarbons, (PAHs) were quantitatively related to the physicochemical properties of the parent structures. The goal of the work was to identify how much information regarding overall mutagenicity of PAHs reside in the ...

Journal of Applied Physics, 1987

An approximate formula for electron-hole generation rate has been proposed. The proposed approxim... more An approximate formula for electron-hole generation rate has been proposed. The proposed approximation is found to give good representation of the actual generation rate provided by Dunbar and Hauser and by Fossum. In order to determine the applicability of this approximation attempts have been made to calculate short-circuit current, open-circuit voltage, and solar cell efficiency of an n+p silicon solar cell. The calculations involve consideration of nonuniform doping, spatial dependence of the band, and drift field for the n+ region, and band gap narrowing, Shockley–Read–Hall recombination, and Auger recombination for both n+ and p regions. The variations of short-circuit current, open-circuit voltage, and solar cell efficiency with doping concentration of the substrate p region are found to be in good agreement with results obtained from experiments. The trend of the results indicates that proper optimization of the width and impurity concentration of the diffused n region, of t...

Journal of Applied Physics, 2004

A metallization technique has been developed for obtaining low resistance Ohmic contact to n-GaN.... more A metallization technique has been developed for obtaining low resistance Ohmic contact to n-GaN. The metallization technique involves the deposition of a metal layer combination Ta/Ti/Ni/Au on an n-GaN epilayer. It is observed that annealing at 750 °C for 45 s leads to low contact resistivity. Corresponding to a doping level of 5×1017 cm−3, the contact resistivity of the contact ρS=5.0×10−6 Ω cm2. The physical mechanisms underlying the realization of low contact resistivity is investigated using current–voltage characteristics, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and energy dispersive x-ray spectrometry.

Journal of Applied Physics, 2006

In this work we have demonstrated nanoscale GaN device structures made from individual GaN nanowi... more In this work we have demonstrated nanoscale GaN device structures made from individual GaN nanowires and electrical contacts utilizing focused ion beam (FIB) induced Pt deposition. These GaN nanowires were grown by direct reaction of Ga vapor with NH3 and had diameters ranging from 100nmto250nm and lengths up to 200μm. As-grown nanowires were dispersed on SiO2 coated p++ Si substrate. A 30keV Ga+ ion beam was used to dissociate (trimethyl)methylcyclopentadienyl-platinum precursor for depositing Pt contacts to GaN nanowires. FIB-deposited Pt contacts to GaN nanowires showed nonlinear I-V characteristics, which turned linear after annealing at 500°C for 30s in argon. Resistivity of a GaN nanowire measured using a four terminal contact geometry fabricated by depositing Pt with a FIB was in the range of 5×10−3Ωcm. Temperature dependent resistivity measurement of the GaN nanowire revealed semiconducting behavior with a weak temperature dependence of the resistivity. In this study both Oh...

Journal of Applied Physics, 2010

Semiconductor nanotubes, including carbon nanotubes, have vast potential for new technology devel... more Semiconductor nanotubes, including carbon nanotubes, have vast potential for new technology development. The fundamental physics and growth kinetics of these nanotubes are still obscured. Various models developed to elucidate the growth suffer from limited applicability. An in-depth investigation of the fundamentals of nanotube growth has, therefore, been carried out. For this investigation, various features of nanotube growth, and the role of the foreign element catalytic agent (FECA) in this growth, have been considered. Observed growth anomalies have been analyzed. Based on this analysis, a new shell model and a general hypothesis have been proposed for the growth. The essential element of the shell model is the seed generated from segregation during growth. The seed structure has been defined, and the formation of droplet from this seed has been described. A modified definition of the droplet exhibiting adhesive properties has also been presented. Various characteristics of the ...

IEEE Transactions on Electron Devices, 1992

IEEE Transactions on Electron Devices, 1990

A theoretical model for the I-V characteristics of ion-implanted metal semiconductor field-effect... more A theoretical model for the I-V characteristics of ion-implanted metal semiconductor field-effect transistors (MESFET's) has been developed. A new formula for effective drift saturation velocity for electrons, and a Gaussian approximation for the inverse of reduced distances in the channel have eased the process of formulation. Theoretical formulas for early saturation of drain current and transconductance obtained in the framework of the Lehovec-Zuleeg procedure, are quite simple and accurate. When calculated results from the present model are compared with available experiments, an encouraging correspondence between the two is observed. When used to study the appropriateness of the velocity overshoot and the softening of pinchoff voltage, it suggests that both of these phenomena are real in shortchannel MESFET's, and these need to be carefully accounted for in a realistic model. The model is equally applicable also to ion-implanted JFET's.