Research Labs

Vision

(of Materials Science Group)

Our job is to produce Novel Materials

and use it to develop products.

Ours will be a Materials Application Centre,

which will be in close touch with industry

and provide service to industry.

We dream it would become an Invention factory.

1.Materials: Synthesis and Processing:

Ion Implanter

Ion?beam modification of materials is a major experimental facility. The Department has a high current ion ? implanter which is rare of its kind. It can provide mass analyzed ion beams of energy 30 keV of any species ranging from hydrogen to uranium. We now have facilities for synthesizing specific materials in thin films form. These include vacuum evaporation, electron beam, and plasma deposition. Besides this Department also have conventional furnace up to 1200 0C for oxidation and diffusion. Crystal growth is one of the thrust areas. The Department has been doing excellent work in this field. In fact, Department has designed and developed the Vertical Directional Solidification (VDS) technique for crystal growth which is novel, simpler, a method that does not need any seed.

X-ray Diffractometer:

CN2005 ( Regaku Miniflex ) is an semi automated X-ray diffractometer. It is useful in qualitative analysis of substances, particularly crystalline materials.. This compact diffractometer system comprises of three main components;

(i) High voltage generator (30 keV), with X-ray tube (1kW) in the tube shield.

(ii) Goniometer Unit; Measurable angular range: +30 ~ + 1600 (2q)

(iii) Scanning speed: ? o/min, 2o/min at 50 Hz.

(iv) Counter: A sealed proportional counter (SPC-20)

Fourier Transform Infrared Spectrometer (FTIR):

The covalent bond between the atoms in molecules is not perfectly rigid and it is flexible to some extent. Hence the vibrational motions are observed in molecules. After absorbing infrared radiation molecules vibrate at different modes, giving rise to closely packed absorption bands. Various bands present in IR spectrum will correspond to the characteristics functional groups and bonds. Thus IR spectroscopy is the most powerful technique to analyze highly specialized materials. We have acquired Fourier Transform Infrared (FTIR)[JASCO FT/IR ? 610] Spectrometer. This model has a very large frequency range (6700 cm-1 to 350 cm-1) and very useful for IR characterization of the materials.

LCR Meter:

HP 4284A (20 Hz to 1MHz) is capacitance meter that can measure the capacitance in the ranges of 0.01 nF to 9.99999 F. Voltage to the test sample can be given internally. This instrument is used extensively in semiconductor device characterization e.g. Shottky diode and MOS

Hall Measurement System (HMS):

HMS characterizes the electronic transport properties of materials over a wide range of temperature and magnetic field. All manner of semi ? conducting material may be characterized in this system. This system include electromagnet-based configuration that provide field strengths to about 10 kG at the sample. Operation to temperatures as low as 77 K is possible with LN2.

Rapid Thermal Annealing (RTA) System:
Rapid Thermal Annealing (RTA) is one of the important techniques used in the processing and study of semiconductor materials. A complete stand-alone microprocessor controlled RTA system has been designed and fabricated at the Department of Physics, University of Mumbai by A.M.Narsale, M.M.Belakar, K.V.Sukhatankar, under an NSC/UGC project.

PC Based I-V Measurement Setup:

A low cost PC based system to measure, record and plot Current-Voltage (I-V) characteristics of the semiconductor samples has been designed and developed in the Department. The system consists of a Programmable Voltage Source, Current to Voltage Converter and Data Acquisition System. The applied voltage can be varied upto ?20 Volts in the step voltage of ?10 mV. The current can be measured in four different ranges from 10 mA to 10 mA with current resolution ? 5 nA. User-friendly software written in Turbo C in an interactive mode stores the I-V data and plot it either simultaneously or later when required. The system has excellent accuracy, repeatability and reliability.

Plasma Discharge Cleaning System:

From the DAE-BRNS grants, the facility for ultra high vacuum system for plasma discharge cleaning was fabricated. Plasma assisted etching of metal surfaces in UHV clean environment is investigated. Further, the studies on plasma induced compound layer formation are in progress.

Surface Physics :

The Surface Physics laboratory consists of Ultra High Vacuum (UHV) chamber with a thin film deposition unit and Perkin Elmer?s Low Energy Electron Diffraction (LEED) and work function measurement set up for surface analysis. Many parts of this unit are fabricated indigenously. The ultra high vacuum is produced using Sputter Ion pump (Varian model Picotorr 350) which is capable of achieving vacuum of 10-10 torr. The chamber is so designed so that additional surface analytical techniques can be incorporated in the system. The analytical unit consists of LEED apparatus for surface analysis and a view port from where the LEED patterns can be photographed. We have also designed and fabricated the sample manipulator and sample holder capable of x,y,z and tilt motion with heating facility using electron bombardment technique. Besides, an electron beam retarding technique has been developed by us in conjunction with LEED optics to determine change in work function of the substrate on adsorption. We study the deposition of transition metals [W(110)] and semiconductor [Si(111)] with adsorption of rare earths on adsorbates at various thicknesses. Change in work function with temperatures at various coverages and the corresponding changes in crystal structures by LEED are noted by us.

Mossbauer Spectrometer:
A conventional 57Fe source based Mossbuer spectrometer available in Transmission mode. Conversion Electron Mossbauer Spectrometer is under development.

Jandel Four Point probe:
Resistivity measurements of wide range of samples from metallic to semiconducting can be carried out. .

X-ray Fluorescence Spectrometer:
A high resolution Si(Li) detector for X-ray spectroscopy is available. 50 mCi 241Am source is being procured. Quantitative analysis of concentration of high Z elements in any solid samples can be carried out.

Potentiostat:

[Ref. 15] Potentiodynamic polarization curves of untreated, Ti-deposited and (Ti- deposited + nitrogen implanted) 316 SS at various doses.

Corrosion resistance studies of metallic samples can be carried out using this equioment

2 Nuclear Physics:
Nuclear structure studies are pursued using the Inter University UGC sponsored Pelletron research facility at the Nuclear Science Centre, New Delhi. The main research is on the structure of nuclei far from stability and that of transitional nuclei.

The states of nuclei that have a low probability of being populated are being studied by using a recoil mass separator coupled to an array of high-resolution Ge detectors. The observations of identical rotational bands in 78Kr and 80Rb is a sensational discovery. The Nuclear Physics laboratory in the Department is equipped with scintillation spectrometers, gas detectors, silicon surface barrier detectors and related associated electronics. Multi channel analyzers interfaced to PCs are also regularly used in experiments. M.Sc. students are also using these Facilities regularly.

3 IT and Virtual Instrumentation labs:

For PGDIT course there are 50 computers networked with Internet connection. For Virtual Instrumentation development 10 kits and LABVIEW software is available.

Research

Major experimental facility is in the field of ion beam modification of materials. The Department has a high-current ion implantor, which is one of the few implantors of its kind in the whole world. It can provide mass analysed ion beams of energy 30 keV of any species ranging from hydrogen to uranium. Its mass dispersion is 1 cm for ion specie having mass number A=50, Major application of such a beam is to produce novel phases having exotic properties in the near surface region of any material. Thin films, plasma physics, condensed matter physics; surface physics, solid-state device physics, etc. are some of the areas in which active experimental research is being carried in the Department. Research work is also carried out in theoretical physics. This includes research in nonlinear phenomena including nonlinear optics, laser physics, space plasma physics and particle physics. Department is also a major user of UGC sponsored National Facility - Pelletron Heavy Ion Accelerator at Nuclear Science Centre, New Delhi. Research programmes are actively pursued in the fields of Nuclear Structure Physics and Materials Science.

Department has collaborative programmes with National & International Institutes : (i) Nuclear Science Centre (New Delhi) (ii) TIFR, (iii) BARC, (iv) Inter University Consortium (IUC), Indore (v) The Institute of Mathematical Sciences, Chennai (vi) Mehta Research Institute, Allahabad. (vii) University of Wisconsin, U.S.A. (viii) Lawrence Berkley National Laboratory, California, USA (ix) Alabama A&M University, U.S.A. (x) University of Trento, Italy (xi) University of Gotingen, Germany, (xii) Warsaw Military Institute of Technology, Poland

Collaborations with industries are as follows:

(i) Intel Inc. USA, (ii) National Instruments, USA (iii) Multi-Arc India Ltd., Mumbai

Contribution of the
Department of Physics, University of Mumbai
in the field of
?Surface Modification of Materials by Ion Beams?

Department of Physics of the University of Mumbai has a strong research group working in the field of Novel Materials. The Department strength lies in the field of Ion Implantation, which was established in the early seventies and the Department has contributed significantly in this field [1].

The Department has focused on using ion beams to develop device grade materials and study fundamental aspects of radiation damage. Our unique programmes of Solid State Electronics and Solid State Physics have led us to embark upon new materials useful for nano-scale devices made by ion beam, chemical and other techniques.

Pioneering work on Ion Implantation in India: Department of Physics, under the leadership of Late Professor M. C. Joshi, took pioneering efforts in Developing Ion Implantation facility in early seventies and has been in the forefront in studying different aspects of ion beam modifications of materials. The Department ion implanter was indigenously built (at BARC and modified in the Department of Physics) and although old now, it has unique characteristics such as high current ion beam and good resolving power. It can deliver ion beams of any element from hydrogen to uranium and has a Resolving power of 1 in 500. For gaseous species the currents are up-to 100 ?A.

Taking advantage of high current capability, university scientists concentrated on forming oxide, nitride and oxy-nitride layers on silicon using ion implantation, which were shown to be useful in forming MOS structure [2 and references therein].

Professor M. C. Joshi

[Ref. 1] The IR transmission spectra of Si samples implanted with various doses of (16O2)+ ions at 30 kV: curve A, 1 X 1016 ions cm-2; curve B, 2.5 X 1016 ions cm-2; curve C, 1?1017 ions cm-2, curve E, 1?1018 ions cm-2.
[Ref. 2]

Doping in amorphous semiconductor was carried out for the applications to Solar Cells [3]. In basic physics area, it was shown using Hall effect that (Ec - 0.55) eV level is formed using Fe implantations in silicon [4]. Radiation damage studies on Silicon were carried out and mechanism of dislocation network created by ion irradiation was studied [5]. Radiation induced redistribution of atoms was studied [6]. Inverse Kirkindal effect was observed and interpreted using model simulation [7]. Out-diffusion and segregation due to ion beam irradiation have been reported [8]. Mechanism of ion beam mixing has been studied in details [9]. Ion beam modification on metals has been vigorously pursued in the University. Meta-stable phase formation and radiation induced phase transformations have been studied [10]. Quasi-crystal formation by ion beam mixing [11] and improvement in quality of diamond films were demonstrated [12].

[Ref. 12] LASER Raman spectra of diamond films on WC-Co tool bit. Unirradiated and irradiated with 100 MeV 127I at dose 5 x 1013ions/cm2
[Ref.12] (a and b) SEM images of diamond film

Meta-stable nitrogen-rich gamma and epsilon nitrides on steel surfaces have been formed [13]. Ion beam induced amorphization and meta-stable phase formation were understood based on a modelduetoMeidema[14]. Applications of ion beams to produce corrosion and wear resistant surfaces have been demonstrated [15 and references therein]. Spin orientation of metallic glasses have been studied using Mossbauer spectroscopy [16]. Radiation induced effects on the conduction mechanism of GaAs has been studied after MeV ion irradiation of Si+ and Sn+ ions [17]. Titanium and Vanadium silicides have been formed by ion implantation [18] Recently the Department scientists have been focusing on using ion beam methods to form device grade nano-phase materials [19] and Iron-slilcide clusters in Si [20].

International Recognition: Our contribution to the field of ion implantation is internationally recognized. One of our scientists was invited at the Fifteenth International Conference on ?Accelerators and their Industrial Applications? held in Denton, Texas, USA held during October 1998. One of the faculty members has an Indo-Italian collaborative project funded by DST and Italian Foreign Ministry. Many faculty members have contributed in different International conferences on Ion beam modifications and related areas.

[Ref. 21] Retarding potential and current for clean W(110) and after absorption of Sm at room temperature.
[Ref. 21] Retarding voltage as a function of substrate tempereture for various thicknesses of Sm/W(110).

Indigenous Development: University has developed indigenously Low Energy Electron Diffraction system, which is being used to study work functions of different metals [21]. Plasma system has been developed and being used for basic plasma studies and surface modifications [22]. Low cost Mossbauer spectrometer has been developed using a microprocessor kit [19]. Many other instruments and vacuum systems are developed in-house. University scientists have indigenously developed a vertical gradient type crystal growth set up [23]. The set up was used to grow single crystals of InSb, GaSb etc.

Recognition by Peers on Indigenous Development: Rapid Thermal annealing system developed by the University Scientists appeared on the cover page of a recent Physics News published by IPA [24, 25].

Rapid Thermal annealing system developed by the University Scientists [24, 25].
Control of size of nano-particles using pre-mixing dose [35]

Technology Development and collaborations with Industry: One of the faculty members interacted with local industry to develop a couple of technologies. He developed commercial Plasma Nitrider and it is in commercial use in the industry. AlTiN and CrN coatings were developed using cathodic arc PVD technique and are now regular products of that industry [26, 27].

Nano-phase materials: Recent work on embedded metallic nanoparticles for optical switching has been received well with the international community. Control on the size and density of nanoparticles was obtained by ?Defect Engineering? developed using ion beams [29].

Recognition by DST: Department of Physics, University of Mumbai has been identified for support under the ?Funds for Improvement in S&T Infrastructure in Universities and Higher Education? (FIST) programmed of the DST for a period from 2001 to 2006.

Recognition by UGC: Department of Physics, University of Mumbai has been recognized for the thrust area ?Materials Science? by the UGC at a level of DRS for the Xth Plan period under their Special Assistance Programme.

References:

[1] J. Dylewski and M. C. Joshi, Thin Solid Films, 35 (1976) 327

[2] S.K. Dubey and A.D. Yadav, Nuclear Instruments and Methods-B, 143 (1998) 493

[3] P. Sekhar, M. C. Joshi, K. L. Narsimhan and S. Guha, Solid Stat Communications, 26 (1978) 973

[4] S.V. Joshi and M.C. Joshi, Physics Status Solidi (a), 64 (1981) K7

[5] L. E. Thailamani and M.C. Joshi, Nuclear Instruments and Methods, (1982)

[6] D. C. Kothari and A. Miotello, J. of Physics C: Condensed Matter Physics (Letters) 1 (1989) 10619.

[7] D. C. Kothari, V. N. Kulkarni, A. Miotello, L. Guzman, G. Linker and B. Strehlahu, Surface Coating and Technology, 83 (1996) 88.

[8] V. K. Asundi, M. C. Joshi et al, Radiation Effects, 49 (1980)39

[9] S. K. Sinha, D. C. Kothari, K. M. Vigen, T. Som, V. N. Kulkarni, S. Panchapakesan and K. G. M. Nair, Nucl. Instr. & Meth B, 159 (1999) 227.

[10] D. C. Kothari, P. Scardi, S. Gialanella and L. Guzman, Philosophical Magazine-B, B61 (1990) 627.

[11] L. M. Gratton, A. Miotello, C. Tosello, D. C. Kothari, G. Principi and A. Tomasi, Nuclear Instruments and Methods-B, B59/60 (1990) 1541

[12] U. R. Mhatre, A. N. Kale, Atul Kulkarni, S. B. Ogale, S. M. Kanetkar, D. Kanjilal and D. C. Kothari, Vacuum, 48 (1998) 999-1003

[13] D. C. Kothari, M. R. Nair, A. A. Rangwala, K. B. Lal, P. D. Prabhawalkar and P. M. Raole, Nuclear Instruments and Methods-B, B7/8 (1985) 235.

[14] S. Vaitheeswaran, H. Parvez and D. C. Kothari, Surface Coating and Technology, 83 (1996) 30

[15] M. Vigen Karimi, S.K. Sinha, D.C. Kothari, A.K. Khanna and A.K. Tyagi, Surface Coating and Technology, 158-159 (2002) 609

[16] K.V. Amrute, U.R. Mhatre, S.K. Sinha, D.C. Kothari, R. Nagarajan and D. Kanjilal, Pramana, 58 (2002) 1093

[17] A.M. Narsale, Yousuf Pyar Ali, Uma Bhabhani, V.P. Salvi, B.M. Arora, D. Kanjilal and G.K. Mehta, J. of Applied Physics, 82 (1997) 4228

[18] V.P. Salvi, S.V. Vidwans, A.A. Rangwala, B.M. Arora, Kuldeep and Animesh K. Jain,. Nuclear Instruments and Methods-B, 28 (1987) 242-246

[19] NSC-UFUP Project (2002-05), Preparation of Ag and Ag2O doped glasses By Ion Exchange followed by Oxygen Implantation and Silver Irradiation, Santosh K. Haram and D.C. Kothari

[20] NSC-UFUP Project (2000-03), Study of defects in high energy Fe implanted silicon, S.K. Dubey and A.D. Yadav

[21] Anup Lohani and Varsha Bhattacharya, J. Electron Spectrosc. and rel. phen., 122 (2002) 79

[22] T.M. Desai, V.S. Salgaonkar, A.B. Shukla, N.K. Joshi, S.V. Gogawale and G.L. Bhat, Vacuum (1994)

[23] D.B. Gadkari, K.B. Lal, A.P. Shah and B.M. Arora, J. Cryst. Growth (Rapid Communication), 173 (1997) 585

[24] Physics News, Vol. 32, Nos 3&4, (2001)

[25] M.M. Belekar, A.M. Narsale, K.V. Sukhatankar, B.M. Arora, Y. P. Ali, Ind. J. Pure and Applied Physics, 40 (2002) 79

[26] N. Bazznella, R. Checchetto, A. Miotello, B. Patton, A. N. Kale and D. C. Kothari, Appl. Phys. Lett., 81 (2002) 3762

[27] D. C. Kothari and A. N. Kale, Surface Coating and Technology, 158-159 (2002) 174

[28] Santosh K. Haram and Alen J. Bard, J. Phys. Chem. B, 105 (34) (2001) 8192

[29] M. K. Patel, B. J. Nagare, D. B. Bagul, S. K. Haram, , D. C. Kothari., Surface Coating and Technology (2004) , accepted for publication

Contribution of the Department of Physics, University of Mumbai in

Pure Physics Research

The Department has an active research programme in the area of Nuclear Structure at high angular momentum in the mass region, A~100 and A~150. The !% UD Pelletron accelerator facility at the Nuclear Science Centre is used by the researchers in the Department in a vary major way. The Department has an active research programme in the theoretical aspects of high energy physics. The work related to ?top quark? and ?standard model? is of particularly worth mentioning. Theoretical study of Dusty Plasma is undertaken to understand the dynamical behavior of dust structures in space and astrophysical plasmas. Electronic structure calculations and hyperfine field studies in metals and metallic alloys have been carried out. Inner-shell ionization and evaluation of the atomic structure parameters is the area of studies of theoretical atomic physics group. Liquid crystal phase transitions have been detected using a Fabry Perot Etalon.

From the pages of academic reports???

Comments of UGC IXth Plan Committee:

The Department has developed a number of experiments for teaching the conceptual features of the subject under COSIP/ULP programmes. Two excellent text books for the PG course have been written by the faculty members and published by reputed publishing houses. These books are followed and prescribed by institutions like IITs and other Universities in India.

The members of the faculty appear to work as a team, thereby providing a healthy academic atmosphere which is conducive to the effective deployment of funds received by the Department.
The committee during its visit was impressed by the excellence of their upkeep. In the last 5 years it has received funding to the tune of Rs. 10.9 millions from various sources including UGC. The major equipments acquired over the years are used without any of them falling into disuse or being allowed to become dysfunctional. The faculty has published 98 papers, a majority of them being accepted by the International Journals of reput. ..??.

Comments of Academic Audit Committee of Mumbai University:

The committee appreciates the work done by the Department in teaching as well as research, in-spite of various constraint. ??..The committee agrees to proposed re-organization of research efforts into three major areas:

a) Materials Science (including Solid State Electronics)

b) Nuclear Physics

c) Theoretical Physics

??The committee recommends 10 additional posts to be created and filled during the next 5 years. ?... It may be important for the Department to become autonomous. ?.The committee recommends a separate building of its own, constructed according to its need and specifications. ?..To further improve the teaching laboratory, research facilities and other infra-structure support, the committee recommends immediate special funding for the Department???.