Phd thesis on zno

Phd thesis on zno

Chapter VI, which is the core part of this thesis work, is mainly devoted to the characterization study of ZnO-based building blocks. The emphasis is given to the fabrication of dense, uniform and defect-free ZnO layers for the memristive application by Thesis On Zno If you order paper now, here is how we will proceed with your assignment: Place your order and give details about your essay We will find a professional paper writer whose skills, education and experience will Thesis On Zno be the best fit for this particular task Zno Nanoparticles Phd Thesis their bids under the posted order, waiting for a client to settle on which writer, among those who left their bids, they want to choose. The bidding system is developed based on Zno Nanoparticles Phd Thesis what is used in auctions, where a

(PDF) Optical properties of the plasma hydrogenated ZnO thin films | Neda Neykova - blogger.com

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Optical properties of the plasma hydrogenated ZnO thin films Journal of Electrical Engineering. Neda Neykova. Download Download PDF Full PDF Package Download Full PDF Package This Paper. A short summary of this paper. The thickness of thin film was evaluated by reflectance interferometry using the metallographic optical microscope fiber coupled to the CCD spectrometer operating in nm spectral range. The optical absorption was measured by photothermal deflection spectroscopy operating in nm spectral range.

The change of the optical absorption edge and the increase of the infrared optical absorption was detected in hydrogenated ZnO. The increase of the infrared optical absorption goes with the increase of the electrical conductivity.

We conclude that the plasma hydrogenation of the intrinsic ZnO thin films is related to increase of the free carrier phd thesis on zno. K e y w o r d s: metal oxide, magnetron sputtering, thin films, reflectance interferometry, phd thesis on zno, photothermal deflection spec- troscopy 1 Introduction trical conductivity increases after hydrogen plasma treat- ment [6].

We observed the increase of the infrared opti- The phd thesis on zno undoped zinc oxide ZnO is an elec- cal absorption in hydrogenated ZnO films correlated with trically resistive wide band gap semiconductor optically the increase of the electrical conductivity. Therefore, we transparent for the visible light with the large exciton concluded that the increase of the electrical conductivity binding energy, high electron mobility, high refractive in- in hydrogen plasma treated ZnO layers is related to the dex and diversity of nanostructure shapes which makes it increase of the free carrier concentration indicating the suitable for many applications in the optoelectronic de- post-deposition hydrogen plasma doping.

vices, optical sensors, and biosensors [1]. The resistivity In this paper, we introduce the reflectance interferom- of ZnO film can be significantly reduced by the addition etry microscope for phd thesis on zno evaluation of the thin film thick- of H 2 in Ar during RF sputtering, likely due to the hy- ness with the high spatial resolution.

We also phd thesis on zno the drogen donor of ZnO [2]. First-principles calculations of differences in the optical absorption coefficient spectra of the optical and electronic properties of H-doped ZnO sys- the oxidized and plasma hydrogenated ZnO thin films.

tem show that there is a strong band formation between H and O, while H intersects the ZnO bond and increases charge of jointed oxygen, due phd thesis on zno decrement of volume of supercell.

The energy band gap and the optical absorp- 2 Experimental procedures tion edge shift to higher energy due to the Burstain Moss effect[3]. Secondary electrons emitted from the tar- sample holder 75 mm. The residual pressure in vacuum get surface as a result of the ion bombardment play an chamber prior deposition was 0. The magnetic field important role in maintaining the cold plasma [4].

Re- was induced electromagnetically by current 4. We have studied the effect of hydrogen plasma The thin layer inspector GUI interface of the thin film model reflectance spectra The post-deposition hydrogenation was performed in and measured spectra, see Fig, phd thesis on zno.

The user finds the cor- capacitively coupled plasma CCP reactor operating at rect thin film thickness by changing manually the model room temperature at radio frequency RF of The manual approach has an advantage that at the working pressure of 70 Pa. The ion energy was con- it can be applied also for partly scattering samples where trolled by the applied RF power, phd thesis on zno.

During plasma treat- the reflectance spectra are suppressed. ment, the density of RF power was kept about 0. Prior the hydrogen plasma treatment, rectly using the photothermal deflection spectroscopy the chamber was evacuated to a base pressure of 1 mPa. PDS with high sensitivity of four orders of magnitude Here we introduce for the first time the fast and sim- [9].

The heat absorbed in the sample immersed in trans- ple optical setup to evaluate the thickness of thin film parent liquid in quartz phd thesis on zno generates the periodical by the optical reflectance interferometry using phd thesis on zno met- thermal waves in the medium surrounding the sample allographic trinocular optical microscope MTM IN- causing the periodical deflection of the laser beam phd thesis on zno TRACO MICRO, Ltd.

The microscope is equipped with lel to the sample surface. The amplitude of the deflection 10 W halogen lamp as a light source, the external power normalized on the black sample spectra gives the opti- supply and the fiber coupled TE cooled 16 Bit CCD spec- cal absorption of thin film. The laser beam deflection is trometer operating in the wavelength range of to detected by the position detector, phd thesis on zno.

For details see [10]. nm with 0. The optical fiber is coupled The surface morphology was observed using Scan- to camera eyepiece on top of the microscope. The spatial ning Electron Microscopy SEM MAIA3-TESCAN.

at resolution varies from about 0. mm objective 5 ×. The Agilent a digital multimeter and the 4-point method was employed to measure the electrical resistance To evaluate the thickness we developed the user- of the ZnO films using and the van der Pauw contact friendly software that reads directly the ASCII data ex- configuration based on four nm thick Al electrodes ported from CCD spectrometer [8].

Our program works evaporated in each corner of the sample. The consecutive in the semi-infinity substrate approximation to speed the measurements were performed with the voltage source ap- calculations. The optical parameters of the thin film and plied to two adjacent electrodes and the current being substrate are either constants or the tabulated values measured at the opposite side electrodes, [11]. Chang, J, phd thesis on zno.

Neykova, J. Souček, Z. The SEM image phd thesis on zno the top view of nanocrystaline ZnO Fig. It takes about ms to measure one spectrum and when repeated 10 × to reduce noise, the total time is about 1 s, phd thesis on zno.

This allows manually moni- hydrogenated toring the homogeneity of the thin thickness by moving the sample using microscope XY stage. The thin film thickness nm evaluated from the reflectance spectra correlates with thickness shown by the cross section scanning electron microscopy image, see Fig. annealed Figure 4 shows the optical absorption coefficient spec- tra of the annealed and hydrogenated nanocrystalline ZnO thin films. Dispersion of the optical absorption coefficient α of the reduced in the infrared region and the electrical resistiv- annealed and hydrogenated ZnO thin films ity increased by 4 orders of magnitude to 10 2 Ωcm.

Thus, we conclude that the near infrared optical absorption in the hydrogenated sample is related to the increase of the strate. Figure 2 shows the average grain size about free carrier concentration. The thin film thickness can be directly evaluated from the cross section SEM image in Fig. Using the spectrometer attached to optical micro- optical interference fringes. We have developed the software to simu- by dark signal D, phd thesis on zno. The reference and sample reflectance late the interference fringes of thin film on semi-infinite is measured using image focused on the sample or mirror substrate for simple evaluation of the film thickness and surface.

Prior the measurements, the intensity of the ref- we have shown that it correlates very well with thickness erence spectrum is adjusted using blue color glass filter evaluated from phd thesis on zno cross section scanning electron mi- and two partly crossed polarizing filters. The dark scan is croscopy image. After oxidation due to thermal annealing his MSc degree in optoelectronics and material science from in air, the optical absorption was significantly reduced in National Pintung Phd thesis on zno of Education, Taiwan He the infrared region and the electrical resistivity increased.

worked as a research assistant at the Department of Applied After hydrogen plasma treatment, the increase of the in- Physics, National Pintung University, Taiwan and frared optical absorption, related to free carrier concen- at the Department of Optical Materials, Institute of Physics tration, was detected below the optical absorption edge.

of the Czech Academy of Sciences, Prague, Czech Republic since He is a PhD student at the Faculty of Biomed- The increase of the optical absorption goes with the in- ical Engineering Czech Technical University in Prague since crease of the electrical conductivity related to the increase His research interests include deposition of thin films, of the free carrier concentration.

plasma treatment, surface functionalization, optical and elec- trical measurements. He is the co-author of 3 impacted journal Acknowledgements papers and 3 conference papers. The work was supported by the project J of Neda Neykova, born in Bulgariareceived her the Czech Science Foundation.

PhD degree in Physical Engineering in the Department of Solid State Engineering, Czech Technical University in Prague and the Rectors Award for outstanding doctoral thesis ZnO References nanocolumns for thin film silicon solar cells with high effi- ciency She has worked as a researcher at the Depart- [1] U. Özgür, Y. Alivov, C. Liu, A. Teke, M. Reshchnikov, S. ment of Optical Materials, Institute of Physics of the Czech Dogan, V. Avrutin, S. Cho and H. nanostructures, surface plasma modification of nanostructures [2] L.

Chen, W. Chen, J. Wang, F. Hong and Y, phd thesis on zno. proceedings papers H-factor 5. Bustanafruz, M. Fazli, M.

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