Sensor Devices & Metrology Section

The group is involved in the development of Solid State Gas Sensors mainly for atmospheric pollutants.

Current R & D projects highlights:

Thin Film Devices & Metrology group mainly focused on the development of thin film (metal oxide, III- nitride) based smart & reliable sensors for accurate measurement of environment pollutant gases. Extensive efforts have been put to develop solid state gas sensors for CO & NOx gases. Prototype MO based sensing device for CO gas has been designed and fabricated on alumina substrate with integrated platinum hot plate.

Further, it is essentially required that the commercially available gas sensors need to be tested and certified in order to make reliable measurements.  CSIR-NPL being the national measurement institute (NMI) will provide traceability for all the required parameters and also the calibrated gases for sensor measurements. Keeping in view of this, we are in the process of creating a National facility for testing and certification of solid state gas sensors following ISO 17025:2017.



DP Head:

Dr. Govind, Senior Principal Scientist

+91-11-45609503, +91-9811930735


Dr. M. Senthil Kumar, Principal Scientist


Dr. Preetam Singh, Principal Scientist

+91-11-45608609, +91-9717927838


Technical Support:

Mr. Lalit Goswami, Technical Officer

Mr. Saket Vihari, Technician

Ms. Kamla, Work Assistant




  1. Photoemission Spectroscopy
  2. Description: A multiprobe surface analysis system (Scienta Omicron, Germany) was used for X-ray & Ultraviolet photoemission spectroscopic (XPS/UPS) measurements as shown in Figure 2. The system is equipped non-monochromatized (AlK, MgK), monochromatized (AlK)) and a helium discharge lamp (He(I) & He(II)) for UPS measurements. The system also equipped with a charge neutralization gun, sputter gun to eliminate the build-up charges and surface preparation before measurements, respectively. The system also contains microscopic techniques such as Scanning Tunneling Microscopy and Atomic Force Microscopy (RT to 100K). Besides this, the system also has techniques such as Auger Electron spectroscopy, Scanning electron spectroscopy and Temperature Programmed Desorption.

  3. Photoluminescence (PL) Spectroscopy
  4. Description: Photoluminescence  is a nondestructive  luminescence technique  that can be used to probe the electronic structure of materials. In this method a laser source or a lamp with energy larger  than the material band-gap is employed to excite electrons from valence band to conduction band. Electrons and holes recombine   spontaneously either directly from conduction to valence band or involving different defect and excitonic levels in the band-gap. The emitted radiation is collimated, focused by lenses and directed to the monochromator that disperses the light into separate wavelengths.  The dispersed light is then recorded by a CCD based camera detector and intensity vs wavelength plot can be viewed on a computer screen. Fig. 3 shows the Edinburgh FLS-980 PL system equipped with a continuous wave UV excitation frequency (325 nm) He-Cd laser and a Xenon lamp (200-1800 nm) were used as the excitation sources. The optical detector has the detection range between 230-1700 nm.


  5. Spectroscopic Ellipsometer (M/S: J.A. Woollam, Model: V-VASE)
  6. Description:   Elliptically polarized light falls on thin film sample and the reflected beam will be detected by a detector. The polarization of the incident beam will be disturbed by thin film and thus reflected beam carries the information regarding the film.  The ellipsometer records the spectra of the variation of phase and the variation of the amplitude of the minor and major axes in terms of its ratio w.r.t wavelength, for different incident angles set. These spectra will be fitted theoretically by a range of expected n, k, d values using software adopting related theoretical models.  Thus n, k, and d values are determined.

    Measurements can be made in the Spectral range 200 – 1700 nm at variable angle of incidence.

  7. Deep Level Transient Spectrometer (DLTS) :

    Description: It is used to investigate defects present in thin films/devices. Schottky /p-n junction (one side lightly doped) is most preferred sample . In DLTS technique difference in the charge state of depletion is noted in terms of capacitance transient using a lock-in-amplifier or double box-car averaging techniques, for a set of time intervals, over a range or temperature and forms a spectrum.  The so resulted capacitance / current spectrum is analyzed by signal processing methods. Max. 10 mm X 10 mm sample size. Measurements can be carried out in the Temperature range: LNT to 730 K.

  9. Optical fiber based spectrometer (Model: Avantes)

    Description: It is a direct measurement of transmission, reflection, absorption and irradiance of the sample. Optical fibers carry the light to fall on the sample and to feed to detector. Measurements can be carried out in the Spectral range: 200 – 1700 nm.  Sample can be both thin film and liquid.

  11. Stylus-based Surface Profiler (M/s Ambios, Model: XP-200)

    Description:   This measures the step height made in the when the surface is moved relative to the contact profilometer's stylus. Measurements can be carried out for max. scan length: 55 mm.


  1. Plasma Assisted Molecular Beam Epitaxy (PAMBE)
  2. Description: The Riber Compact 21 PAMBE system is shown in Figure is used to grow highly quality and extremely crystalline III-Nitride materials and provide precise control over the growth parameters. The highest quality material and highest reliability are key criteria in the design and manufacture of the system. It consists of three UHV chambers namely: Load-lock chamber (to load/unload the 6-platen cassette carrying wafers into the system), Buffer chamber (to store and outgas the wafers) & Growth chamber (to perform the epitaxial growth of compound semiconductor materials). Other main parts of the system include a number of pumps and gate valves (to achieve and maintain ultra-high vacuum), a lift (to move cassette vertically between load-lock and buffer chamber) and a magnetic transfer arm (to transfer the platen between buffer and growth chamber). The main growth chamber is a vertical UHV reactor equipped with standard effusion cells, (to supply ultrapure III group materials and dopants), a rf–plasma source (ADDON) to supply active nitrogen (N*) species, a Reflection High Energy Electron Diffraction (RHEED) gun (to real time monitor the growth of crystalline layers during the growth processes), a residual gas analyser (RGA), a rotating manipulator, a flux gauge, cryo-panels, a cryo pumping system and viewports. Moreover, the substrate temperature in growth chamber was monitored by an optical pyrometer and kSA bandit temperature sensor.

  3. Pulsed Laser Deposition System:
  4. Description: The smart PLD system from SVT Associates is used to deposit compound semiconductor layers. In pulsed laser deposition process, a high energy laser beam is used to ablate the target material and the ablated material is then directed towards substrate for thin film deposition. A Coherent KrF excimer laser of 248 nm is employed for the target ablation. The system has substrate rotation and heating facility, in-situ RHEED, etc. for high quality growth of thin layers. Metal nitrides and oxides can be deposited using this system.

  5. Dicing Saw:
  6. Description: The cutting machine has a spindle motor and three step motors. A diamond wheel attached to the spindle motor is used to cut materials. Wafers/substrates up to 8 cm x 8 cm can be cut into pieces in mm scale. The cutting rate depends on the hardness of the materials to be cut.

  7. Thermal Evaporation System:
  8. Description : Thermal evaporation is q simple thin film coating technique. The system is used for the deposition of metal and oxide films such as SnO 2 , ZnO, etc. for fabrication of solid state gas sensors. The equipment has substrate heater, thickness monitor, co-evaporation facility, etc.

  9. Thermal & E-beam Evaporation (In-house fabricated):
  10. Description: Fully manual operational, substrate temperature up to 400 °C. For the deposition of metal and oxide thin films.

  11. Magnetron sputtering system (In-house fabricated):
  12. Description :    Fully manual operational, substrate temperature up to 700 °C. For the deposition of metal and oxide thin films using RF / DC electrical power.

  13. Hot-wire CVD system (In-house fabricated)

Description:   Fully manual operational, substrate temperature upto 850 °C and filament temperature 1500-2200 °C.

Key Publications

Key Publications (Last Five years)

  1. Mukesh Kumar, S.K. Pasha and Govind, Kinetically Controlled Growth of Gallium on Stepped Si (553) surface, Applied Surface Science 283 , 1071-1075, (2013)
  2. Amit Kumar Singh Chauhan, Nirosh M. Eldose, Monu Mishra, Asad Niazi, Lekha Nair and Govind Gupta,  Evolution of kinetically controlled In-induced surface structure on Si (557) surface, Applied Surface Science 314, 586 (2014)
  3. Shibin Krishna T.C. and Govind Gupta, Band alignment and Schottky behaviour of InN/GaN  heterostructure grown by low temperature low energy ion bombardment, RSC Advances, 4 , 27308-27314 (2014).
  4. Mukesh Kumar, S.K. Pasha, Shibin Krishna T.C. Avanish Pratap Singh, Pawan Kumar,  Bipin Kumar Gupta and Govind Gupta, Facile Synthesis and Photoluminescence Spectroscopy of 3D-Triangular GaN Nano Prism Islands, Dalton-Transaction 43, 11855-61 (2014)
  5. Amit Kumar Singh Chauhan,  Asad Niazi, Lekha Nair and Govind Gupta, In induced stable ordering of stepped Si(553) surface, Applied Surface Science 337 145-150 (2015)
  6. Neha Aggarwal Shibin Krishna TC, Lalit Goswami, Monu Mishra, Govind Gupta, K.K. Maurya, Sandeep Singh, Nita Dilawar and Mandeep Kaur,  Extenuation of stress and defects in GaN films grown on MOCVD-GaN/c-sapphire substrate by PAMBE, Crystal Growth & Design 15 (5), 2144–2150 (2015)
  7. Monu Mishra, Shibin Krishna TC, Neha Aggarwal, Saket Vihari and Govind Gupta, Electronic structure analysis of GaN films grown on r- and a-plane sapphire, Journal of Alloys & Compounds 645, 230-234 (2015)
  8. Amit Kumar Singh Chauhan, Mukesh Kumar and Govind Gupta, Catalyst free self-assembled growth of InN nanorings on stepped Si (553) surface, Applied Surface Science-345, 156-161 (2015)
  9. Monu Mishra, Shibin Krishna TC, Neha Aggarwal and Govind Gupta , Surface chemistry and electronic structure of nonpolar and polar GaN films , Applied Surface Science 345, 440-447 (2015)
  10. Monu Mishra, Shibin Krishna TC, Neha Aggarwal, Mandeep Kaur, Sandeep Singh and Govind Gupta , Pits Assisted Oxygen Chemisorption on GaN Surfaces, Physical Chemistry Chemical Physics 17, 15201-15208 (2015)
  11. Anurag G. Reddy, Neha Aggarwal, Shibin Krishna T.C., Manju Singh, Rajib Rakshit and Govind Gupta, Correlation of I-V-T analysis with deep level defects in epitaxial GaN films, Applied Physics Letters, 106, 233501 (2015)
  12. Shibin Krishna T C, Neha Aggarwal, G. Anurag Reddy, Palak Dugar, Monu Mishra, Lalit Goswami, Nita Dilawar, Mahesh Kumar, K K Maurya and Govind Gupta, Probing the correlation between structure, carrier dynamics and defect states of epitaxial GaN film on () sapphire grown by rf-molecular beam epitaxy, RSC Advances 5, 73261-67 (2015)
  13. Palak Dugar, Mahesh Kumar, Shibin Krishna T C, Neha Aggarwal, and Govind Gupta, Carrier relaxation dynamics in defect states of epitaxial GaN/AlN/Si using ultrafast transient absorption spectroscopy, RSC Advances 5, 83969 (2015)
  14. Shibin Krishna T.C, Neha Aggarwal , Monu Mishra, K.K Maurya, Mandeep Kaur, Geetanjali Sehgal,  Sukhveer Singh, Nita Dilawar, Bipin Kumar Gupta and Govind Gupta, Epitaxial growth of high In-content In0.41Ga0.59N/GaN heterostructure on (11-20) Al2O3 substrate, Journal of Alloys & Compounds 658, 470-475 (2016)
  15. Shibin Krishna T.C, Neha Aggarwal, Monu Mishra, K.K Maurya, Sandeep Singh, Nita Dilawar, Subramaniyam Nagarajan and Govind Gupta , Correlation of growth temperature with stress, defect states and electronic structure in epitaxial GaN film grown on c-sapphire via Plasma MBE, Physical Chemistry Chemical Physics, 18 , 8005-8014 (2016)
  16. Monu Mishra, Shibin Krishna, Neha Aggarwal and Govind Gupta, Influence of metallic surface states on electron affinity of epitaxial AlN films, Applied Surface Science, 407, 255 (2017)
  17. Abhiram Gundimeda, Shibin Krishna, Neha Aggarwal, Alka Sharma, Nita Dilawar, K. K. Maurya, Sudhir Husale and Govind Gupta, Fabrication of non-polar GaN based highly responsive and fast UV Photodetector, Applied Physics Letters-110, 103507 (2017),

  19. Neha Aggarwal, Shibin Krishna, Alka Sharma, LalitGoswami, Dinesh Kumar, Sudhir Husale, Govind Gupta, Realization of Highly Responsive Self-driven UV Photodetector using GaN Nanoflowers, Advanced Electronic Materials, 1700036 (2017) ,
  20. ,

  21. Monu Mishra, Shibin Krishna, Neha Aggarwal, Abhiram Gundimeda and Govind Gupta
  22. Electronic and Chemical Structure Analysis of Nanoflowers Decorated GaN and AlGaN/GaN heterostructure, Journal of Alloys & Compound, 708, 385 (2017)    

  23. Monu Mishra, Abhiram Gundimeda, Shibin Krishna, Neha Aggarwal, BhaskerGahtori, Nita Dilawar, Ved Varun Agrawal, Manju Singh, RajibRakshit and Govind Gupta
  24. Wet chemical etching induced stress relaxed nanostructures on polar & non-polar epitaxial GaN films, Physical Chemistry Chemical Physics, 19, 8787 (2017)

  25. Shibin Krishna, Anurag G. Reddy, Neha Aggarwal, Mandeep Kaur, Sudhir Husale, Dinesh Singh, Manju Singh, Rajib Rakshit, K.K. Maurya and Govind Gupta
  26. Enhanced current transport in GaN/AlN based single and double barrier heterostructures, Solar Energy & Solar Materials, 170, 160 (2017)

  27. Shibin Krishna, Alka Sharma, Neha Aggarwal, Sudhir Husale and Govind Gupta
  28. Enhanced Photo-responsivity and fast photo-response of Indium Nitride ultra-broadband photo-detector, Solar Energy & Solar Materials- 172, 376-383(2017,

  29. LalitGoswami,  Rajeshwari Pandey and Govind Gupta, Epitaxial Growth of GaN Nanostructure by PA-MBE for UV Detection Application, Applied Surface Science, 449, 186-192 (2018)
  30. Monu Mishra, Abhiram Gundimeda, , Shibin Krishna, Neha Aggarwal, Lalit Goswami, Bhasker Gahtori, Biplab Bhattacharya, Sudhir Husale and Govind Gupta, Surface Engineered Nonpolar GaN Ultraviolet Photodetectors, ACS Omega 3 (2),  2304–2311 (2018)
  31. Shubhendra Kumar Jain, Neha Aggarwal,  Shibin Krishna, Rahul Kumar, Sudhir Husale, Vinay Gupta and Govind Gupta, GaN-UV photodetector integrated with Asymmetric MSM structure for enhanced responsivity, Journal of Material Science: Materials in Electronics 1-6 (2018)
  32. Dependence of Al incorporation on growth temperature during laser molecular beam epitaxy of Al x Ga 1-x N epitaxial layers on sapphire (0001), PrashantTyagi, Ch Ramesh, S.S. Kushvaha, Monu Mishra, Govind Gupta, B.S. Yadav, and M. Senthil Kumar, Journal of Alloys and Compounds, 739 (2018) 122-128. DOI: 10.1016/j.jallcom.2017.12.220
  33. Influence of growth temperature on laser molecular beam epitaxy and properties of GaN layers grown on c-plane sapphire, Ripudaman Dixit, PrashantTyagi, Sunil S.S. Kushvaha, S. Chokalingam, B.S. Yadav, N.D. Sharma and M. Senthil Kumar, Optical Materials, 66 (2017) 142-148.
  34. Quantum confinement effect in low temperature grown homo-epitaxial Gannanowall network by laser assisted molecular beam epitaxy, S.S. Kushvaha, Ch. Ramesh, PrashantTyagi, A.K. Shukla, B.S. Yadav, N. Dilawar, K.K. Maurya and M. Senthil Kumar, Journal of Alloys and Compounds 703 (2017) 466-476. DOI: 10.1039/C5CE02257F .
  35. Influence of laser repetition rate on the structural and optical properties of GaN layers grown on sapphire (0001) by laser molecular beam epitaxy , S. S. Kushvaha, M. Senthil Kumar, B. S. Yadav, Pawan K. Tyagi, Sunil Ojha, K. K. Maurya and B. P. Singh , Crystal Engineering and Communications 18 (2016) 744-753.DOI: 10.1039/C5CE02257F
  36. Structural, optical and electronic properties of homoepitaxialGaNnanowalls grown on GaN template by laser molecular beam epitaxy, S. S. Kushvaha ,   M. Senthil Kumar ,   A. K. Shukla B. S. Yadav ,   Dilip K. Singh ,   M. Jewariya ,   S. R. Ragam  and   K. K. Maurya , RSC Advances 5 (2015) 87818. DOI: 10.1039/C5RA11361J
  37. Detection of dislocation-related midgap levels in pulsed laser deposited GaN by photo-induced current transient spectroscopy, M. Senthil Kumar, K. M. K. Srivatsa, and S. S. Kushvaha, Physica Status Solidi (b) 252 (2015) 800-803. DOI: 10.1002/pssb.20145145
  38. Low temperature Growth of GaN epitaxial layers on sapphire (0001) by pulsed laser deposition using liquid Gallium target, M. Senthil Kumar, S.S. Kushvaha, K.K. Maurya, Science of Advanced Materials, 6 (2014) 1215-1220. DOI:
  39. Highly c-axis oriented growth of GaN film on sapphire (0001) by laser molecular beam epitaxy using HVPE grown GaN bulk target, S.S. Kushvaha, M. Senthil Kumar, K.K. Maurya, M.K. Dalai, Nita D Sharma, AIP Advances 3 (2013) 092109. DOI: .
  40. Ultrafast pump-probe spectroscopy studies of CeO 2 thin ?lm deposited on Ni-W substrate by RF magnetron sputtering, Preetam Singh, K.M.K. Srivatsa, Mukesh Jewariya, Optical Materials, 58, 1-4 (2017). DOI:
  41. X-ray photoelectron spectroscopic studies of CeO 2 thin ?lms deposited on Ni-W (100), c-Al 2 O 3 (0001) and Si (100) substrates, Preetam Singh, K.M.K. Srivatsa, Arun Barvat, Prabir Pal, Current Applied Physics 16, 1388-1394 (2016). DOI:


Inspire Faculty/Postdoctoral Fellow:
Dr. Vishal Baloria, DST-Inspire Faculty   
Dr. Neha Aggarwal, CSIR-Research Associate

Ph.D. Students:
Mr. Shubhendra K. Jain, CSIR-Senior Research Fellow
Mr. Prashant Tyagi, CSIR-Senior Research Fellow
Mr. Amit Kumar Mauraya, UGC-Senior Research Fellow
Mr. Pargam Vashistha UGC-Junior Research Fellow
Ms. Debashrita Mahana, CSIR-Junior Research Fellow
Mr. Anuj Sharma, UGC-Junior Research Fellow
Mr. Aditya, UGC-Junior Research Fellow
Mr. Rahul Godiwal, CSIR-Junior Research Fellow
Mr. Amit Gangwar, UGC-Junior Research Fellow
Ms. Urvashi Varshney UGC-Junior Research Fellow
Ms. Preeti Goswami UGC-Junior Research Fellow
Ms. Stuti Srivastava, UGC-Junior Research Fellow

Alumina of the Group:
    1. Dr. Amit Kumar Singh Chauhan, Ph.D.  (2016), currently Assistant Prof. DDU University, Gorakhpur
    2. Dr. G. Anurag Reddy, M.Tech.(AcSIR) and Ph.D. student, currently working as Scientist at CSIR-National Physical Laboratory, New Delhi
    3. Dr. Deepak Chhikara, Ph.D (2016), currently working as Assistant Prof. at DCRUST, Murthal, Haryana
    4. Dr. Shibin Krishna TC, Ph.D. (2018), currently working as Post-doctoral Fellow at KAUST, UAE
    5. Dr. Monu Mishra, Ph.D. (2018), Current working as  Senior Project Scientist, IIT Delhi
    6. Mr. G. Abhiram, M.Tech. and Ph.D. student, currently pursuing Ph.D. from University of Cambridge, UK.