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BETA
Faraz, Sadia Muniza
Alternative names
Publications (8 of 8) Show all publications
Asghar, M., Iqbal, F., Faraz, S., Jokubavicius, V., Wahab, Q. & Syväjärvi, M. (2012). Characterization of deep level defects in sublimation grown p-type 6H-SiC epilayers by deep level transient spectroscopy. Paper presented at 26th International Conference on Defects in Semiconductors. Elsevier, 407(15)
Open this publication in new window or tab >>Characterization of deep level defects in sublimation grown p-type 6H-SiC epilayers by deep level transient spectroscopy
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2012 (English)Conference paper, Published paper (Refereed)
Abstract [en]

In this study deep level transient spectroscopy has been performed on boron-nitrogen co-doped 6H-SiC epilayers exhibiting p-type conductivity with free carrier concentration (N-A-N-D)similar to 3 x 10(17) cm(-3). We observed a hole H-1 majority carrier and an electron E-1 minority carrier traps in the device having activation energies E-nu + 0.24 eV, E-c -0.41 eV, respectively. The capture cross-section and trap concentration of H-1 and E-1 levels were found to be (5 x 10(-19) cm(2), 2 x 10(15) cm(-3)) and (1.6 x 10(-16) cm(2), 3 x 10(15) cm(-3)), respectively. Owing to the background involvement of aluminum in growth reactor and comparison of the obtained data with the literature, the H-1 defect was identified as aluminum acceptor. A reasonable justification has been given to correlate the E-1 defect to a nitrogen donor.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
SiC; DLTS; Acceptors; Donors; Doping; Deep level defects; LED
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-79662 (URN)10.1016/j.physb.2011.08.085 (DOI)000305790800057 ()
Conference
26th International Conference on Defects in Semiconductors
Available from: 2012-08-14 Created: 2012-08-13 Last updated: 2012-10-21
Asghar, M., Iqbal, F., Faraz, S. M., Jokubavicius, V., Wahab, Q. & Syväjärvi, M. (2012). Study of deep level defects in doped and semi-insulating n-6H-SiC epilayers grown by sublimation method. Paper presented at -. Elsevier, 407(15)
Open this publication in new window or tab >>Study of deep level defects in doped and semi-insulating n-6H-SiC epilayers grown by sublimation method
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2012 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Deep level transient spectroscopy (DLTS) is employed to study deep level defects in n-6H-SiC (silicon carbide) epilayers grown by the sublimation method. To study the deep level defects in n-6H-SiC, we used as-grown, nitrogen doped and nitrogen-boron co-doped samples represented as ELS-1, ELS-11 and ELS-131 having net (N-D-N-A) similar to 2.0 x 10(12) cm(-3), 2 x 10(16) cm(-3) and 9 x 10(15) cm(3), respectively. The DLTS measurements performed on ELS-1 and ELS-11 samples revealed three electron trap defects (A, B and C) having activation energies E-c - 0.39 eV, E-c - 0.67 eV and E-c - 0.91 eV, respectively. While DLTS spectra due to sample ELS-131 displayed only A level. This observation indicates that levels B and C in ELS-131 are compensated by boron and/or nitrogen-boron complex. A comparison with the published data revealed A, B and C to be E-1/E-2, Z(1)/Z(2) and R levels, respectively.

Place, publisher, year, edition, pages
Elsevier, 2012
Keywords
n-Type 6H-SiC; Sublimation growth process; DLTS; Deep level defects; Surface defect; Co-doping
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-79661 (URN)10.1016/j.physb.2011.08.036 (DOI)000305790800056 ()
Conference
-
Available from: 2012-08-14 Created: 2012-08-13 Last updated: 2012-10-21
Muniza Faraz, S. (2011). Physical simulation, fabrication and characterization of Wide bandgap semiconductor devices. (Licentiate dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Physical simulation, fabrication and characterization of Wide bandgap semiconductor devices
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Wide band gap semiconductors, Zinc Oxide (ZnO), Gallium Nitride (GaN) and Silicon Carbide (SiC) have been emerged to be the most promising semiconductors for future applications in electronic, optoelectronic and power devices. They offer incredible advantages in terms of their optical properties, DC and microwave frequencies power handling capability, piezoelectric properties in building electromechanical coupled sensors and transducers, biosensors and bright light emission. For producing high quality devices, thermal treatment always plays an important role in improving material structural quality which results in improved electrical and optical properties. Similarly good quality of metal–semiconductor interface, sensitive to the semiconductor surface, is always required.

In this thesis we report the study of the interface states density for Pd/Ti/Au Schottky contacts on the free-standing GaN and post fabrication annealing effects on the electrical and optical properties of ZnO/Si hetero-junction diodes. The determination of interface states density (NSS) distribution within the band gap would help in understanding the processes dominating the electrical behavior of the metal–semiconductor contacts. The study of annealing effects on photoluminescence, rectification and ideality factor of ZnO/Si hetero-junction diodes are helpful for optimization and realization to build up the confidence to commercialize devices for lightening. A comparison of device performance between the physical simulations and measured device characteristics has also been carried out for pd/ZnO Schottky diode to understand the behavior of the devices.

This research work not only teaches the effective way of device fabrication, but also obtains some beneficial results in aspects of their optical and electrical properties, which builds theoretical and experimental foundation for much better and broader applications of wide band gap semiconductor devices.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2011. p. 28
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1492
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-68076 (URN)LIU-TEK-LIC-2011: 31 (Local ID)978-91-7393-148-9 (ISBN)LIU-TEK-LIC-2011: 31 (Archive number)LIU-TEK-LIC-2011: 31 (OAI)
Supervisors
Available from: 2011-05-10 Created: 2011-05-10 Last updated: 2020-02-03Bibliographically approved
Noor, H., Klason, P., Faraz, S. M., Nour, O., Ul Wahab, Q., Willander, M. & Asghar, M. (2010). Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices. JOURNAL OF APPLIED PHYSICS, 107(10)
Open this publication in new window or tab >>Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices
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2010 (English)In: JOURNAL OF APPLIED PHYSICS, ISSN 0021-8979, Vol. 107, no 10Article in journal (Refereed) Published
Abstract [en]

Various well-known research groups have reported points defects in bulk zinc oxide (ZnO) [N-D (intrinsic): 10(14)-10(17) cm(-3)] naming oxygen vacancy, zinc interstitial, and/or zinc antisite having activation energy in the range of 0.32-0.22 eV below conduction band. The attribution is probably based on activation energy of the level which seems not to be plausible in accordance with Vincent et al., [J. Appl. Phys. 50, 5484 (1979)] who suggested that it was necessary to become vigilant before interpreting the data attained for a carrier trap using capacitance transient measurement of diodes having ND greater than 10(15) cm(-3). Accordingly the influence of background free-carrier concentration, ND induced field on the emission rate signatures of an electron point defect in ZnO Schottky devices has been investigated by means of deep level transient spectroscopy. A number of theoretical models were tried to correlate with the experimental data to ascertain the mechanism. Consequently Poole-Frenkel model based on Coulomb potential was found consistent. Based on these investigations the electron trap was attributed to Zn-related charged impurity. Qualitative measurements like current-voltage and capacitance-voltage measurements were also performed to support the results.

Place, publisher, year, edition, pages
American Institute of Physics, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-57405 (URN)10.1063/1.3428426 (DOI)000278182400083 ()
Note
Original Publication: Hadia Noor, P Klason, Sadia Muniza Faraz, Omer Nour, Qamar Ul Wahab, Magnus Willander and M Asghar, Influence of background concentration induced field on the emission rate signatures of an electron trap in zinc oxide Schottky devices, 2010, JOURNAL OF APPLIED PHYSICS, (107), 10, 103717. http://dx.doi.org/10.1063/1.3428426 Copyright: American Institute of Physics http://www.aip.org/ Available from: 2010-06-18 Created: 2010-06-18 Last updated: 2014-01-15
Muniza Faraz, S., Ashraf, H., Imran Arshad, M., Hageman, P. R., Asghar, M. & Ul Wahab, Q. (2010). Interface state density of free-standing GaN Schottky diodes. Semiconductor Science and Technology, 25(9), 095008
Open this publication in new window or tab >>Interface state density of free-standing GaN Schottky diodes
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2010 (English)In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 25, no 9, p. 095008-Article in journal (Refereed) Published
Abstract [en]

Schottky diodes were fabricated on the HVPE-grown, free-standing gallium nitride (GaN) layers of n- and p-types. Both contacts (ohmic and Schottky) were deposited on the top surface using Al/Ti and Pd/Ti/Au, respectively. The Schottky diode fabricated on n-GaN exhibited double barriers with values of 0.9 and 0.6 eV and better performance in the rectification factor together with reverse and forward currents with an ideality factor of 1.8. The barrier height for the p-GaN Schottky diode is 0.6 eV with an ideality factor of 4.16. From the capacitance-voltage (C-V) measurement, the net doping concentration of n-GaN is 4 x 10(17) cm(-3), resulting in a lower reverse breakdown of around -12 V. The interface state density (N-SS) as a function of E-C-E-SS is found to be in the range 4.23 x 10(12)-3.87 x 10(11) eV(-1) cm(-2) (below the conduction band) from Ec-0.90 to E-C-0.99. Possible reasons responsible for the low barrier height and high ideality factor have been addressed.

Place, publisher, year, edition, pages
Iop Publishing Ltd, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-59253 (URN)10.1088/0268-1242/25/9/095008 (DOI)000281221200009 ()
Available from: 2010-09-10 Created: 2010-09-10 Last updated: 2017-12-12Bibliographically approved
Ashraf, H., Imran Arshad, M., Muniza Faraz, S., Ul Wahab, Q., Hageman, P. R. & Asghar, M. (2010). Study of electric field enhanced emission rates of an electron trap in n-type GaN grown by hydride vapor phase epitaxy. Journal of Applied Physics, 108(10)
Open this publication in new window or tab >>Study of electric field enhanced emission rates of an electron trap in n-type GaN grown by hydride vapor phase epitaxy
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2010 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, no 10Article in journal (Refereed) Published
Abstract [en]

Electric field-enhanced emission of electrons from a deep level defect in GaN grown by hydride vapor phase epitaxy has been studied. Using the field dependent mode of conventional deep level transient spectroscopy (DLTS), several frequency scans were performed keeping applied electric field (12.8-31.4 MV/m) and sample temperature (300-360 K) constant. Arrhenius plots of the resultant data yielded an activation energy of the electron trap E ranging from E-c -0.48 +/- 0.02 eV to E-c-0.35 +/- 0.02 eV, respectively. The extrapolation of the as-measured field dependent data (activation energy) revealed the zero-field emission energy (pure thermal activation energy) of the trap to be 0.55 +/- 0.02 eV. Various theoretical models were applied to justify the field-enhanced emission of the carriers from the trap. Eventually it was found that the Poole-Frenkel model associated with a square well potential of radius r=4.8 nm was consistent with the experimental data, and, as a result, the trap is attributed to a charged impurity. Earlier, qualitative measurements like current-voltage (I-V) and capacitance-voltage (C-V) measurements were performed, and screening parameters of the device were extracted to ascertain the reliability of DLTS data.

Place, publisher, year, edition, pages
American Institute of Physics, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-63959 (URN)10.1063/1.3499669 (DOI)000285005000073 ()
Note
Original Publication: H. Ashraf, M. Imran Arshad, Sadia Muniza Faraz, Qamar Ul Wahab, P. R. Hageman and M. Asghar, Study of electric field enhanced emission rates of an electron trap in n-type GaN grown by hydride vapor phase epitaxy, 2010, Journal of Applied Physics, (108), 10, 103708. http://dx.doi.org/10.1063/1.3499669 Copyright: American Institute of Physics http://www.aip.org/ Available from: 2011-01-10 Created: 2011-01-10 Last updated: 2017-12-11
Muniza Faraz, S., Noor, H., Asghar, M., Willander, M. & Wahab, Q. u. (2009). Modeling and simulations of Pd/n-ZnO Schottky diode and its comparison with measurements. Advanced Materials Research, 79-82, 1317-1320
Open this publication in new window or tab >>Modeling and simulations of Pd/n-ZnO Schottky diode and its comparison with measurements
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2009 (English)In: Advanced Materials Research, ISSN 1662-8985, Vol. 79-82, p. 1317-1320Article in journal (Refereed) Published
Abstract [en]

Modeling of Pd/ZnO Schottky diode has been performed together with a set of simulations to investigate its behavior in current-voltage characteristics. The diode was first fabricated and then the simulations were performed to match the IV curves to investigate the possible defects and their states in the bandgap. The doping concentration measured by capacitancevoltage is 3.4 x 1017 cm-3. The Schottky diode is simulated at room temperature and the effective barrier height is determined from current voltage characteristics both by measurements and simulations and it was found to be 0.68eV. The ideality factor obtained from simulated results is 1.06-2.04 which indicates that the transport mechanism is thermionic. It was found that the recombination current in the depletion region is responsible for deviation of experimental values from the ideal thermionic model deployed by the simulator.

Keywords
ZnO, Schottky contact, Barrier height
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-68075 (URN)10.4028/www.scientific.net/AMR.79-82.1317 (DOI)
Available from: 2011-05-10 Created: 2011-05-10 Last updated: 2014-01-15Bibliographically approved
Muniza Faraz, S., Alvi, N. u., Henry, A., Nur, O., Willander, M. & Wahab, Q. u.Post fabrication annealing effects on electrical and optical characteristics of n-ZnO nanorods/p-Si heterojunction diodes.
Open this publication in new window or tab >>Post fabrication annealing effects on electrical and optical characteristics of n-ZnO nanorods/p-Si heterojunction diodes
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Annealing effects on optical and electrical properties of n-ZnO/p-Si heterojunction diodes are studied. ZnO nanorods are grown on p-Si substrate by aquous chemical growth technique. As grown samples were annealed at 400 and 600 oC in air, oxygen and nitrogen ambient. Structural, optical and electrical characteristics are studied by Scanning Electron Microscopy (SEM), Photoluminescence (PL), Current–Voltage (I-V) and Capacitance-Voltage (CV) measurements. Well aligned hexagonal–shaped vertical nanorods are revealed in SEM. PL spectra indicated higher ultraviolet to visible emission ratio with a strong peak ofnear band edge emission (NBE) and weak broad deep-level emissions (DLE). For device fabrication Al/Pt non-alloyed ohmic contacts have been evaporated. I-V characteristics indicate that annealing in air and oxygen resulted in better rectifying behavior as well as decrease in reverse leakage current. An improvement in PL intensity has been shown by the samples annealed at 400 oC.

Keywords
heterojunction diodes, ZnO on Si, electrical properties, ZnO nanorods
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-68074 (URN)
Available from: 2011-05-10 Created: 2011-05-10 Last updated: 2014-10-08Bibliographically approved
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