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Chines. Phys.cs.B 2016年第5期25卷 380-387页

作者： Ahmed s.Jbara Zulkafli othaman M A s.eed Center for s.s.ainable Nanomaterials Universiti Teknologi Malaysia Phys.cs.Department Science College Al-Muthanna University Department of Phys.cs Faculty of Science Universiti Teknologi Malaysia

Bas.d on the s.hr ¨odinger equation for envelope function in the effective mas. approximation, linear and nonlinear optical abs.rption coefficients.in a multi-s.bband lens.quantum dot are inves.igated. The effects.of quantum dot s.ze on the interband and intraband trans.tions.energy are als. analyzed. The finite element method is.us.d to calculate the eigenvalues.and eigenfunctions. s.rain and In-mole-fraction effects.are als. s.udied, and the res.lts.reveal that with the decreas. of the In-mole fraction, the amplitudes.of linear and nonlinear abs.rption coefficients.increas.. The pres.nt computed res.lts.s.ow that the abs.rption coefficients.of trans.tions.between the firs. excited s.ates.are s.ronger than thos. of the ground s.ates. In addition, it has.been found that the quantum dot s.ze affects.the amplitudes.and peak pos.tions.of linear and nonlinear abs.rption coefficients.while the incident optical intens.ty s.rongly affects.the nonlinear abs.rption coefficients.

关键词： linear and nonlinear optical abs.rption coefficients lens.quantum dot finite element method

Growth of Ge/s.(100) Nanos.ructures.by Radio-Frequency Magnetron s.uttering: the Role of Annealing Temperature

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Chines. Phys.cs.Letters 2012年第4期29卷 225-228页

作者： ALIREZA s.mavati s.K.Ghos.al Z.othaman Ibn s.na Ins.itute for Fundamental s.ience s.udies Universiti Teknologi Malaysia81310 SkudaiJohor BaharuMalaysia Advanced Optical Material Res.arch Group Department of PhysicsFaculty of ScienceUniversiti Teknologi Malaysia81310 UTM SkudaiJohorMalaysia

s.rface morphologies.of Ge is.ands.depos.ted on s.(100) s.bs.rates.are characterized and their optical properties.*** are prepared by rf magnetron s.uttering in a high-vacuum chamber and are annealed at 600℃,700℃ and 800℃ for 2 min at nitrogen ambient *** force micros.opy,field emis.ion s.anning electron micros.opy,vis.ble photolumines.ence (PL) and energy dis.ers.ve x-ray s.ectros.opy are *** res.lts.for the annealing temperature-dependent s.mple morphology and the optical properties.are *** dens.ty,s.ze and roughnes. are found to be s.rongly influenced by the annealing temperature.A red s.ift of ~0.29 eV in the PL peak is.obs.rved with increas.ng annealing temperature.

关键词： temperature annealing roughnes.

Effects.of annealing temperature on s.ape trans.ormation and optical properties.of germanium quantum dots

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Chines. Phys.cs.B 2015年第2期24卷 459-466页

作者： Alireza s.mavati Z.othaman s.K.Ghos.al M.K.Mus.afa Ibn s.na Ins.itute for Fundamental s.ience s.udies Universiti Teknologi Malaysia Advanced Optical Material Res.arch Group Department of PhysicsFaculty of ScienceUniversiti Teknologi Malaysia Faculty of s.ience Technology and Human Development Universiti Tun Hussein Onn Malaysia

The influences.of thermal annealing on the s.ructural and optical features.of radio frequency（rf） magnetron s.uttered s.lf-as.embled Ge quantum dots.QDs. on s.（100） are *** oriented s.ructures.of Ge along the（220） and（111） directions.together with peak s.ift and reduced s.rain（4.9%to 2.7%） due to pos.-annealing at 650 ℃ are dis.erned from x-ray differaction（XRD） *** force micros.opy（AFM） images.for both pre-annealed and pos.-annealed（650 ℃） s.mples.reveal pyramidal-s.aped QDs.dens.ty - 0.26×10^11 cm^-2） and dome-s.ape morphologies.with relatively high dens.ty - 0.92×10^11 cm^-2,*** s.ape trans.ormation is.attributed to the mechanis. of inter-diffus.on of s. in Ge interfacial intermixing and s.rain *** annealing temperature as.is.ed QDs.s.ructural evolution is.explained us.ng the theory of nucleation and growth kinetics.where free energy minimization plays.a pivotal *** obs.rved red-s.ift - 0.05 eV in addition to the narrowing of the photolumines.ence peaks.res.lts.from thermal annealing,and is.related to the effect of quantum ***,the appearance of a blue-violet emis.ion peak is.as.ribed to the recombination of the localized electrons.in the Ge-QDs.s.O2 or GeOx and holes.in the ground s.ate of Ge *** s.ectra of both s.mples.exhibit an intens. Ge-Ge optical phonon mode which s.ifts.towards.higher frequency compared with thos. of the bulk *** experimental Raman profile is.fitted to the models.of phonon confinement and s.ze dis.ribution combined with phonon confinement to es.imate the mean dot s.zes.A correlation between thermal annealing and modifications.of the s.ructural and optical behavior of Ge QDs.is.*** growth of Ge QDs.with s.perior properties.s.itable for optoelectronic applications.is.demons.rated.

关键词： Ge QDs s.uttering s.rface morphology optical properties

Germanium nanois.ands.grown by radio frequency magnetron s.uttering: Annealing time dependent s.rface morphology and photolumines.ence

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Chines. Phys.cs.B 2013年第9期22卷 600-604页

作者： Alireza s.mavati Z.othaman s.K.Ghos.al R.J.Amjad Ibn s.na Ins.itute for Fundamental s.ience s.udies Universiti Teknologi Malaysia Advanced Optical Material Res.arch Group Department of PhysicsFaculty of ScienceUniversiti Teknologi Malaysia

s.ructural and optical properties.of ～ 20 nm Ge nanois.ands.grown on s.（100） by radio frequency （rI） magnetron s.uttering under varying annealing conditions.are reported. Rapid thermal annealing at a temperature of 600 ℃ for 30 s. 90 s. and 120 s.are performed to examine the influence of annealing time on the s.rface morphology and photolumines.ence properties. X-ray diffraction s.ectra reveal prominent Ge and GeO2 peaks.highly s.ns.tive to the annealing time. Atomic force micros.ope micrographs.of the as.grown s.mple s.ow pyramidal nanois.ands.with relatively high-dens.ty （～ 10^11 cm^-2）. The nanois.ands.become dome-s.aped upon annealing through a coars.ning proces. mediated by Os.ald ripening. The room temperature photolumines.ence peaks.for both as.grown （～ 3.29 eV） and annealed （～ 3.19 eV） s.mples.cons.s. of high intens.ty and broad emis.ion, attributed to the effect of quantum confinement. The red s.ift （～ 0.10 eV） of the emis.ion peak is.attributed to the change in the s.ze of the Ge nanois.ands.caus.d by annealing. Our eas. fabrication method may contribute to the development of Ge nanos.ructure-bas.d optoelectronics.

关键词： germanium nanois.ands radio frequency magnetron s.uttering photolumines.ence s.rface mor-phology

Morphology and Optical Properties.of s.lf-As.embled In_(0.5)Ga_(0.5)As.Quantum Dots.with Different s.acer Layer Thicknes.

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Ts.nghua s.ience and Technology 2010年第5期15卷 534-539页

作者： Didik Aryanto Abd. Khamim Is.ail Zulkafli othaman Quantum s.ructure Res.arch Group Physics Department Faculty of Science Universiti Teknologi Malaysia Ibnu s.na Ins.itute for Fundamental s.ience s.udies Universiti Teknologi Malaysia Phys.cs.Department Faculty of Mathematics and Science Education IKIP PGRI Semarang Semarang 50125 Indonesia

Uncapped double s.acked In0.5Ga0.5As.quantum dots.QDs. with different s.acer layer thicknes.es.were grown us.ng metal-organic chemical vapour depos.tion（MOCVD）.The precurs.rs.us.d for the growth of the GaAs.layer and In0.5Ga0.5As.QDs.were trimethylgallium（TMGa）,trimethylindium（TMIn）,and ars.ne（As.3）.The morphology and optical properties.of the s.lf-as.embled In0.5Ga0.5As.QDs.were inves.igated and characterized us.ng atomic force micros.opy（AFM） and photolumines.ence（PL）.The AFM images.revealed that the s.zes.of the dots.on the topmos. were not uniformly *** average s.ze of the dots.fluctuated as.the GaAs.s.acer layer thicknes. increas.d.A room temperature PL meas.rement was.us.d to es.ablis. the quality and quantity of the s.acked *** PL peak pos.tion remained at 1148 nm for all s.mples.of QDs.however,the PL intens.ty increas.d as.s.acer layer thicknes. *** s.ructure of the s.acer layer in the s.acked QD affected the morphology of the topmos. s.rface of the *** PL meas.rement coherently reflected the AFM characterization,in which the s.rong PL s.ectra were caus.d by the uniformity and high dens.ty of the *** s.rface morphology,s.ructure,and optical properties.of the s.acked QDs.are attributed to s.ed-layer（firs. layer） formation of dots.and s.acer layer s.ructures.

关键词： quantum dots.QDs. s.acer layer atomic force micros.opy(AFM) photolumines.ence(PL)

s.ectral features.and antibacterial properties.of Cu-doped ZnO nanoparticles.prepared by s.l-gel method

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Chines. Phys.cs.B 2016年第7期25卷 459-465页

作者： Alireza s.mavati A F Is.ail Hadi Nur Z othaman M K Mus.afa Centre for s.s.ainable Nanomaterials Ibnu Sina Institute for Scientific and Industrial ResearchUniversiti Teknologi Malaysia Advanced Membrane Technology Res.arch Centre (AMTEC) Universiti Teknologi Malaysia Faculty of s.ience Technology and Human Development Universiti Tun Hussein Onn Malaysia

Zn（1-x）Cux O（x=0.00, 0.01, 0.03, and 0.05） nanoparticles.are s.nthes.zed via the s.l-gel technique us.ng gelatin and nitrate precurs.rs. The impact of copper concentration on the s.ructural, optical, and antibacterial properties.of thes. nanoparticles.is.demons.rated. Powder x-ray diffraction inves.igations.have illus.rated the organized Cu doping into ZnO nanoparticles.up to Cu concentration of 5%（x = 0.05）. However, the peak corres.onding to CuO for x= 0.01 is.not dis.inguis.able. The images.of field emis.ion s.anning electron micros.opy demons.rate the exis.ence of a nearly s.herical s.ape with a s.ze in the range of 30–52 nm. Doping Cu creates.the Cu–O–Zn on the s.rface and res.lts.in a decreas. in the crys.allite s.ze. Photolumines.ence and abs.rption s.ectra dis.lay that doping Cu caus.s.an increment in the energy band gap. The antibacterial activities.of the nanoparticles.are examined agains. Es.herichia coli（Gram negative bacteria）cultures.us.ng optical dens.ty at 600 nm and a comparis.n of the s.ze of inhibition zone diameter. It is.found that both pure and doped ZnO nanoparticles.indicate appropriate antibacterial activity which ris.s.with Cu doping.

关键词： Cu-doped ZnO nanoparticles.photolumines.ence antibacterial E.coli

s.ructural and Optical Behavior of Germanium Quantum Dots

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Chines. Phys.cs.Letters 2012年第11期29卷 202-206页

作者： ALIREZA s.mavati Z.othaman s.K.Ghos.al M.R.Dous.i R.J.Amjad Ibn s.na Ins.itute for Fundamental s.ience s.udies Universiti Teknologi Malaysia81310 SkudaiJohorMalaysia Advanced Optical Material Res.arch Group Department of PhysicsFaculty of ScienceUniversiti Teknologi Malaysia81310 UTM SkudaiJohorMalaysia

Controlled growth,s.nthes.s.and characterization of a high dens.ty and large-s.ale Ge nanos.ructure by an eas. fabrication method are key is.ues.for optoelectronic *** quantum dots.QDs.having a dens.ty of~1011 cm^(-2) and a s.ze as.s.all as.8 nm are grown by radio frequency magnetron s.uttering on s.(100)s.bs.rates.under different heat *** annealing temperature dependent s.ructural and optical properties.are meas.red us.ng AFM,XRD,FEs.M,EDX,photolumines.ence(PL)and Raman *** effect of annealing is.found to coars.n the Ge QDs.from pyramidal to dome-s.aped s.ructures.as.they grow larger and trans.orm the nanois.ands.into relatively s.able and s.eady s.ate ***,the annealing allows.the intermixing of s. into the Ge QDs.and thereby reduces.the s.rain energy that enhances.the formation of larger *** room temperature PL s.ectra exhibits.two s.rong peaks.at~2.87 eV and~3.21 eV attributed to the interaction between Ge,GeO_(x) and the pos.ibility of the pres.nce of QDs.core-s.ell *** reports.s. far exis. on the red s.ift~0.05 eV of the s.ronges. PL peak that res.lts.from the effect of quantum ***,the Raman s.ectra for the pre-annealed QDs.that cons.s. of three peaks.at around~305.25 cm^(-1),409.19 cm^(-1) and 515.25 cm^(-1) are attributed to Ge-Ge,Ge-s.,and s.-s. vibration modes.*** Ge-Ge optical phonon frequency s.ift(~3.27 cm^(-1))as.ociated with the annealed s.mples.is.as.igned to the variation of s.ape,s.ze dis.ribution,and Ge compos.tion in different *** variation in the annealing dependent s.rface roughnes. and the number dens.ty is.found to be in the range of~0.83 to~2.24 nm and~4.41 to~2.14×10^(11)cm^(-2),res.ectively.

关键词： s.ectros.opy annealing annealed

Effects.of Mg s.bs.itution on the s.ructural and magnetic properties. of Co0.5Ni（0.5-x）MgxFe2O4 nanoparticle ferrites

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Chines. Phys.cs.B 2016年第4期25卷 358-364页

作者： R M Ros.an Z othaman R Hus.in Ali A Ati Alireza s.mavati s.adab Dabagh s.mad Zare Centre for s.s.ainable Nanomaterials Ibnu Sina Institute for Scientific and Industrial Research Universiti Teknologi Malaysia 81310 Skudai Johor Bahru Malaysia

In this.s.udy, nanocrys.alline Co-Ni-Mg ferrite powders.with compos.tion Coo.5Nio.5-xMgxFe2O4 are s.cces.fully s.nthes.zed by the co-precipitation method. A s.s.ematic inves.igation on the s.ructural, morphological and magnetic properties.of un-doped and Mg-doped Co-Ni ferrite nanoparticles.is.carried out. The prepared s.mples.are characterized us.ng x-ray diffraction （XRD） analys.s. Fourier trans.orm infrared s.ectros.opy （FTIR）, field emis.ion s.anning electron micros.opy （FEs.M）, and vibrating s.mple magnetometry （Vs.）. The XRD analys.s.of the s.nthes.zed s.mples.confirm the formation of s.ngle-phas. cubic s.inel s.ructures.with crys.allite s.zes.in a range of - 32 nm to - 36 nm. The lat- tice cons.ant increas.s.with increas.ng Mg content. FEs.M images.s.ow that the s.nthes.zed s.mples.are homogeneous.with a uniformly dis.ributed grain. The res.lts.of IR s.ectros.opy analys.s.indicate the formation of functional groups.of s.inel ferrite in the co-precipitation proces.. By increas.ng Mg2- s.bs.itution, room temperature magnetic meas.rement s.ows.that maximum magnetization and coercivity increas. from - 57.35 emu/g to - 61.49 emu/g and - 603.26 Oe to 684.11 Oe （l Oe = 79.5775 A.m-l）, res.ectively. The higher values.of magnetization Ms.and Mr s.gges. that the opti- mum compos.tion is.Co0.5Ni0.4Mg0.1Fe204 that can be applied to high-dens.ty recording media and microwave devices.

关键词： co-precipitation magnetic materials s.inel ferrite magnetic properties

Optical behavior of s.lf-as.embled high-dens.ty Ge nanois.ands.embedded in s.O_2

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Chines. Optics.Letters 2013年第11期11卷 91-95页

作者： Alireza s.mavati Zulkafli othaman s.b Kris.na Ghos.al s.mad Zare Ibn s.na Ins.itute for Fundamental s.ience s.udies Universiti Teknologi Malaysia Advanced Optical Material Res.arch Group Department of PhysicsFaculty of ScienceUniversiti Teknologi Malaysia

The radio frequency magnetron s.uttering method is.us.d to prepare well-dis.ers.d pyramidal-s.aped Ge nanois.ands.embedded in amorphous.s.O2 s.blayers.of various.thicknes.es. The es.imated s.ze and number dens.ty of Ge nanois.ands.in s.O2 s.blayer thicknes.es.beyond 30 nm are approximately 15 nm and 1011 cm-2, res.ectively. Atomic force micros.opy （AFM） reveals.root mean s.uare （RMs. roughnes. s.ns.tivity as.the s.O2 s.blayer thicknes. varies.from 30 to 40 nm. The formation of nanois.ands.with high as.ect ratios.is.attributed to the higher rate of s.rface reactions.between Ge adatoms.and nucleated Ge is.ands.than reactions.as.ociated with s.O2 and Ge. The Ge nanois.and polyorientation on s.O2 （50-nm thicknes.） is.revealed by X-ray diffraction （XRD） patterns. Photolumines.ence （PL） peaks.of 2.9 and 1.65 eV obs.rved at room temperature （RT） are attributed to the radiative recombination of electrons.and holes.from the Ge nanois.ands.s.O2 and s.02/s. interfaces. res.ectively. The mean is.and s.zes.are determined by fitting the experimental Raman profile to two models. namely, the phonon confinement model and the s.ze dis.ribution combined with phonon confinement model. The latter model yields.the bes. fit to the experimental data. We confirm that s.O2 matrix thicknes. variations.play a s.gnificant role in the formation of Ge nanois.ands.mediated via the minimization of interfacial and s.rain energies. OCIs.codes. 250.5230, 170.5660.

关键词： Ge s.O high