Mathew Joseph | Rguhs Bangalore (original) (raw)

Papers by Mathew Joseph

Research paper thumbnail of p-Type Electrical Conduction in ZnO Thin Films by Ga and N Codoping

Japanese Journal of Applied Physics, 1999

We report the realization of p-type behavior in ZnO thin films, which are prepared by codoping me... more We report the realization of p-type behavior in ZnO thin films, which are prepared by codoping method using Ga (donor) and N (acceptor) as the dopants. Especially, using active N formed by passing N 2 O gas through an electron cyclotron resonance (ECR) plasma source is quite effective for the acceptor doping. We have observed a room temperature resistivity of 2 •cm and a hole concentration of 4 × 10 19 cm −3. These values are enough high for practical applications in various oxide electronic devices.

Research paper thumbnail of Equation of state of refractory materials at very high temperatures—theoretical and experimental studies

Bulletin of Materials Science, 1994

Research paper thumbnail of Fabrication of the low-resistive p-type ZnO by codoping method

Physica B: Condensed Matter, 2001

We have demonstrated the possibility of growing p-type ZnO films by a pulsed laser deposition tec... more We have demonstrated the possibility of growing p-type ZnO films by a pulsed laser deposition technique combined with plasma gas source. The p-type ZnO film has been fabricated by passing N 2 O gas through an electron cyclotron resonance (ECR) or RF plasma source. N 2 O gas is effective to prevent ''O'' vacancy from occurring and introduce ''N'' as an acceptor, at the same time. With Ga and N codoping technique, we have observed a room temperature resistivity of 0.5 O cm and a carrier concentration of 5 Â 10 19 cm À3 in ZnO film on glass substrate. Two-step growth, with a thin ZnO template layer formed at high temperature, is quite effective to realize a well crystallized growth at low temperature. The observed p-type ZnO films will open the door for practical applications in various oxide electronic devices.

Research paper thumbnail of Determination of Thermal Parameters of Vanadium Oxide Uncooled Microbolometer Infrared Detector

International Journal of Infrared and Millimeter Waves, 2003

Vanadium oxide thin films are the potential candidates for uncooled microbolometers due to their ... more Vanadium oxide thin films are the potential candidates for uncooled microbolometers due to their high temperature coefficient of resistance (TCR) at room temperature. A 2D array of 10-element test microbolometer without air-gap thermal isolation structure was fabricated with pulsed laser deposited vanadium oxide as IR sensing layer for the first time. Infrared responsivity of the uncooled microbolometer was evaluated in

Research paper thumbnail of Development of 0.90 0.05 0.05 2 Thin Films by Pulsed Laser Deposition Technique

Solid State Ionics, 2004

ABSTRACT LiCo0.90Mg0.05Al0.05O2 bulk powders are synthesized using combustion process and made in... more ABSTRACT LiCo0.90Mg0.05Al0.05O2 bulk powders are synthesized using combustion process and made into a thin film by depositing on silicon wafer using a pulsed laser ablation technique. A comparative study by SEM (Scanning Electron Microscope) XRD (X-ray diffraction), Infrared spectroscopy and Raman Spectroscopy is performed on both bulk and PLD thin films.

Research paper thumbnail of Determination of boron isotope ratio in boron carbide using a laser mass spectrometric method

Rapid Communications in Mass Spectrometry, 2004

Research paper thumbnail of Laser-mass spectrometric studies on measurement of isotopic ratios–a comparative study using ps and ns pulsed lasers

International Journal of Mass Spectrometry, 2014

The effect of pulse width of Nd-YAG laser on the measurement of isotopic ratios of Li and lighter... more The effect of pulse width of Nd-YAG laser on the measurement of isotopic ratios of Li and lighter rare Q4 earths is studied using an in-house developed Laser Ionization Mass Spectrometer (LIMS) facility. The picosecond (ps) laser seems to provide better data compared to nanosecond (ns) laser and ps laser at 266 nm provides less scatter in the data compared to higher wavelengths. This LIMS method is a relatively simple method to measure the isotopic abundance to within ±1%.

Research paper thumbnail of Quasi-non-destructive isotopic ratio measurement of boron in irradiated control rod B4C pellets using a home-built reflectron time-of-flight mass spectrometer

International Journal of Mass Spectrometry, 2012

An experimental facility has been built for the analysis of the isotopic ratio 10 B/ 11 B in the ... more An experimental facility has been built for the analysis of the isotopic ratio 10 B/ 11 B in the stacked boron carbide (B 4 C) pellets used as control rod in the Fast Breeder Test Reactor (FBTR). Measurements were made on 5 pellets. The values obtained for a control rod removed after the reactor core had seen a peak burn-up of ∼100 GWd/t indicated a consumption of less than 1% of 10 B.

Research paper thumbnail of Development of a reflectron time-of-flight mass spectrometer for non-destructive analysis of isotope ratios in irradiated B4C pellets—Test measurements on an unirradiated control rod pellet

International Journal of Mass Spectrometry, 2008

ABSTRACT A laser mass spectrometric facility is developed using a home-built reflectron time-of-f... more ABSTRACT A laser mass spectrometric facility is developed using a home-built reflectron time-of-flight mass spectrometer (RTOFMS) to analyze the boron isotopic ratio 10B/11B in the irradiated B4C pellets of the FBTR control rod. Compared to other mass spectrometry-based methods, the present method is practically non-destructive and makes it relatively easier to handle irradiated (radioactive) B4C pellets through remote operation. The results with inactive samples indicate that the method yields 10B percentage values, accurate to within ±1%.

Research paper thumbnail of Laser induced vaporization mass spectrometric studies on Si3N4

International Journal of Mass Spectrometry, 1998

An Si 3 N 4 sample was irradiated with an Nd-YAG laser. The species present in the plume were det... more An Si 3 N 4 sample was irradiated with an Nd-YAG laser. The species present in the plume were detected by a quadrupole mass spectrometer (QMS). The species observed were Si, SiN

Research paper thumbnail of Development of a Laser Induced Vaporization Mass Spectrometric Facility

Instrumentation Science & Technology, 1998

... DEVELOPMENT OF A LASER INDUCED VAPORIZATION MASS SPECTROMETRIC FACILITY M. Joseph, N. Sivakum... more ... DEVELOPMENT OF A LASER INDUCED VAPORIZATION MASS SPECTROMETRIC FACILITY M. Joseph, N. Sivakumar Materials Chemistry Division Indira Gandhi Centre for Atomic Research Kalpakkam 603 102, India ABSTRACT ...

Research paper thumbnail of Boron isotope enrichment in nanosecond pulsed laser-ablation plume

Applied Physics A: Materials Science & Processing, 2003

Boron isotopic enrichment is observed in the laser ablation of B 4 C target using nanosecond (ns)... more Boron isotopic enrichment is observed in the laser ablation of B 4 C target using nanosecond (ns) wide 532 nm laser beam of a Nd-YAG laser. B 10 /B 11 ratio of 0.9 against the natural abundance of 0.25 is obtained at a laser power density of 8 × 10 8 W/cm 2 (fluence of 6.4 J/cm 2). The enrichment as a function of laser power density is demonstrated using a quadrupole mass spectrometer. Apart from higher enrichment factor, only singly charged ions are found in the laser plume from the B 4 C target, in contrast to the multiply charged ions from the BN target reported in a recent report using femtosecond (fs) laser pulses. This study indicates the possibility of using less expensive, widely used ns lasers, which can also yield a higher throughput per pulse than a fs laser for isotope enrichment.

Research paper thumbnail of Development of Laser-induced Vaporization Mass Spectrometry to Study Refractory Materials

Rapid Communications in Mass Spectrometry, 1996

An experimental facility has been developed based on laser-induced vaporization of materials, cou... more An experimental facility has been developed based on laser-induced vaporization of materials, coupled with mass spectrometric monitoring of the vapour species. The primary purpose is to measure the vapour pressures of refractory materials in the temperature range 2500– ...

Research paper thumbnail of p-Type Electrical Conduction in ZnO Thin Films by Ga and N Codoping

Japanese Journal of Applied Physics, 1999

We report the realization of p-type behavior in ZnO thin films, which are prepared by codoping me... more We report the realization of p-type behavior in ZnO thin films, which are prepared by codoping method using Ga (donor) and N (acceptor) as the dopants. Especially, using active N formed by passing N 2 O gas through an electron cyclotron resonance (ECR) plasma source is quite effective for the acceptor doping. We have observed a room temperature resistivity of 2 •cm and a hole concentration of 4 × 10 19 cm −3. These values are enough high for practical applications in various oxide electronic devices.

Research paper thumbnail of Equation of state of refractory materials at very high temperatures—theoretical and experimental studies

Bulletin of Materials Science, 1994

Research paper thumbnail of Fabrication of the low-resistive p-type ZnO by codoping method

Physica B: Condensed Matter, 2001

We have demonstrated the possibility of growing p-type ZnO films by a pulsed laser deposition tec... more We have demonstrated the possibility of growing p-type ZnO films by a pulsed laser deposition technique combined with plasma gas source. The p-type ZnO film has been fabricated by passing N 2 O gas through an electron cyclotron resonance (ECR) or RF plasma source. N 2 O gas is effective to prevent ''O'' vacancy from occurring and introduce ''N'' as an acceptor, at the same time. With Ga and N codoping technique, we have observed a room temperature resistivity of 0.5 O cm and a carrier concentration of 5 Â 10 19 cm À3 in ZnO film on glass substrate. Two-step growth, with a thin ZnO template layer formed at high temperature, is quite effective to realize a well crystallized growth at low temperature. The observed p-type ZnO films will open the door for practical applications in various oxide electronic devices.

Research paper thumbnail of Determination of Thermal Parameters of Vanadium Oxide Uncooled Microbolometer Infrared Detector

International Journal of Infrared and Millimeter Waves, 2003

Vanadium oxide thin films are the potential candidates for uncooled microbolometers due to their ... more Vanadium oxide thin films are the potential candidates for uncooled microbolometers due to their high temperature coefficient of resistance (TCR) at room temperature. A 2D array of 10-element test microbolometer without air-gap thermal isolation structure was fabricated with pulsed laser deposited vanadium oxide as IR sensing layer for the first time. Infrared responsivity of the uncooled microbolometer was evaluated in

Research paper thumbnail of Development of 0.90 0.05 0.05 2 Thin Films by Pulsed Laser Deposition Technique

Solid State Ionics, 2004

ABSTRACT LiCo0.90Mg0.05Al0.05O2 bulk powders are synthesized using combustion process and made in... more ABSTRACT LiCo0.90Mg0.05Al0.05O2 bulk powders are synthesized using combustion process and made into a thin film by depositing on silicon wafer using a pulsed laser ablation technique. A comparative study by SEM (Scanning Electron Microscope) XRD (X-ray diffraction), Infrared spectroscopy and Raman Spectroscopy is performed on both bulk and PLD thin films.

Research paper thumbnail of Determination of boron isotope ratio in boron carbide using a laser mass spectrometric method

Rapid Communications in Mass Spectrometry, 2004

Research paper thumbnail of Laser-mass spectrometric studies on measurement of isotopic ratios–a comparative study using ps and ns pulsed lasers

International Journal of Mass Spectrometry, 2014

The effect of pulse width of Nd-YAG laser on the measurement of isotopic ratios of Li and lighter... more The effect of pulse width of Nd-YAG laser on the measurement of isotopic ratios of Li and lighter rare Q4 earths is studied using an in-house developed Laser Ionization Mass Spectrometer (LIMS) facility. The picosecond (ps) laser seems to provide better data compared to nanosecond (ns) laser and ps laser at 266 nm provides less scatter in the data compared to higher wavelengths. This LIMS method is a relatively simple method to measure the isotopic abundance to within ±1%.

Research paper thumbnail of Quasi-non-destructive isotopic ratio measurement of boron in irradiated control rod B4C pellets using a home-built reflectron time-of-flight mass spectrometer

International Journal of Mass Spectrometry, 2012

An experimental facility has been built for the analysis of the isotopic ratio 10 B/ 11 B in the ... more An experimental facility has been built for the analysis of the isotopic ratio 10 B/ 11 B in the stacked boron carbide (B 4 C) pellets used as control rod in the Fast Breeder Test Reactor (FBTR). Measurements were made on 5 pellets. The values obtained for a control rod removed after the reactor core had seen a peak burn-up of ∼100 GWd/t indicated a consumption of less than 1% of 10 B.

Research paper thumbnail of Development of a reflectron time-of-flight mass spectrometer for non-destructive analysis of isotope ratios in irradiated B4C pellets—Test measurements on an unirradiated control rod pellet

International Journal of Mass Spectrometry, 2008

ABSTRACT A laser mass spectrometric facility is developed using a home-built reflectron time-of-f... more ABSTRACT A laser mass spectrometric facility is developed using a home-built reflectron time-of-flight mass spectrometer (RTOFMS) to analyze the boron isotopic ratio 10B/11B in the irradiated B4C pellets of the FBTR control rod. Compared to other mass spectrometry-based methods, the present method is practically non-destructive and makes it relatively easier to handle irradiated (radioactive) B4C pellets through remote operation. The results with inactive samples indicate that the method yields 10B percentage values, accurate to within ±1%.

Research paper thumbnail of Laser induced vaporization mass spectrometric studies on Si3N4

International Journal of Mass Spectrometry, 1998

An Si 3 N 4 sample was irradiated with an Nd-YAG laser. The species present in the plume were det... more An Si 3 N 4 sample was irradiated with an Nd-YAG laser. The species present in the plume were detected by a quadrupole mass spectrometer (QMS). The species observed were Si, SiN

Research paper thumbnail of Development of a Laser Induced Vaporization Mass Spectrometric Facility

Instrumentation Science & Technology, 1998

... DEVELOPMENT OF A LASER INDUCED VAPORIZATION MASS SPECTROMETRIC FACILITY M. Joseph, N. Sivakum... more ... DEVELOPMENT OF A LASER INDUCED VAPORIZATION MASS SPECTROMETRIC FACILITY M. Joseph, N. Sivakumar Materials Chemistry Division Indira Gandhi Centre for Atomic Research Kalpakkam 603 102, India ABSTRACT ...

Research paper thumbnail of Boron isotope enrichment in nanosecond pulsed laser-ablation plume

Applied Physics A: Materials Science & Processing, 2003

Boron isotopic enrichment is observed in the laser ablation of B 4 C target using nanosecond (ns)... more Boron isotopic enrichment is observed in the laser ablation of B 4 C target using nanosecond (ns) wide 532 nm laser beam of a Nd-YAG laser. B 10 /B 11 ratio of 0.9 against the natural abundance of 0.25 is obtained at a laser power density of 8 × 10 8 W/cm 2 (fluence of 6.4 J/cm 2). The enrichment as a function of laser power density is demonstrated using a quadrupole mass spectrometer. Apart from higher enrichment factor, only singly charged ions are found in the laser plume from the B 4 C target, in contrast to the multiply charged ions from the BN target reported in a recent report using femtosecond (fs) laser pulses. This study indicates the possibility of using less expensive, widely used ns lasers, which can also yield a higher throughput per pulse than a fs laser for isotope enrichment.

Research paper thumbnail of Development of Laser-induced Vaporization Mass Spectrometry to Study Refractory Materials

Rapid Communications in Mass Spectrometry, 1996

An experimental facility has been developed based on laser-induced vaporization of materials, cou... more An experimental facility has been developed based on laser-induced vaporization of materials, coupled with mass spectrometric monitoring of the vapour species. The primary purpose is to measure the vapour pressures of refractory materials in the temperature range 2500– ...