scholarly journals Optical spectroscopic analysis of annealed Cd1−xZnxSe thin films deposited by close space sublimation technique

2016 ◽  
Vol 34 (4) ◽  
pp. 828-833 ◽  
Author(s):  
Ijaz Ali ◽  
Amjid Iqbal ◽  
Arshad Mahmood ◽  
A. Shah ◽  
M. Zakria ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Constants ◽  
Empirical Relation ◽  
Optical Transmittance ◽  
Oscillator Model ◽  
Optical Investigation ◽  
Dispersion Parameters ◽  
Zn Content ◽  
Space Sublimation

AbstractCd1−xZnxSe (x = 0, 0.40 and 1) thin films were deposited on a glass substrate at room temperature by closed space sublimation method. Optical investigation has been performed using spectrophotometry and ellipsometry. It has been found that for as deposited films the optical band gap increased and the optical constants decreased with increasing Zn content. To improve the optical properties of Cd1−xZnxSe thin films annealing effect at 400 °C was taken into consideration for various Zn contents. It was observed that the optical transmittance and band gap decreased while optical constants increased with increasing Zn content after annealing. The effects of composition and annealing on the optical dispersion parameters Eo and Ed were investigated using a single effective oscillator model. The calculated value of the average excitation energy Eo obeys the empirical relation (Eo = Eg/2) obtained from the single oscillator model.

STRUCTURAL AND OPTICAL PROPERTIES OF UNDOPED AND SILVER, LITHIUM AND COBALT-DOPED ZnO THIN FILMS

2019 ◽  
Vol 27 (04) ◽  
pp. 1950138
Author(s):  
FATMA MEYDANERİ TEZEL ◽  
İ. AFŞIN KARİPER
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Optical Transmittance ◽  
Refraction Index ◽  
Zno Thin Films ◽  
High Temperature Furnace ◽  
Doped Zno ◽  
Ray Patterns ◽  
Temperature Furnace

Undoped and silver, lithium and cobalt-doped ZnO thin films have been successfully deposited on glass by chemical bath deposition (CBD). The reaction temperature was 50∘C and the films were annealed at 400∘C for 4[Formula: see text]h in a high temperature furnace. UV/VIS spectrum was used to determine optical transmittance, optical band gap ([Formula: see text] and absorbance values of Ag:ZnO, Co:ZnO, Li:ZnO and undoped ZnO thin films. Optical band gap ([Formula: see text] and absorbance values of undoped ZnO, Ag:ZnO, Co:ZnO and Li:ZnO thin films were found as 0.0158, 0.0064, 0.2638, 0.0956 and 3.24, 3.13, 3.27, 2.96 eV, respectively. Extinction coefficients and refraction indexes of the films were found to be 0.0096, 0.0038, 0.0068, 0.019 (extinction coefficient) and 1.26, 1.14, 1.66, 2.33 (refraction index), respectively. X-ray patterns of undoped ZnO, Ag:ZnO, Co:ZnO and Li:ZnO thin films were confirmed as amorphous.

Effect of Flexible Substrates on the Structural and Optical Properties of ZnO Films Deposited by Sputtering Method

2015 ◽  
Vol 1107 ◽  
pp. 678-683 ◽  
Author(s):  
Lam Mui Li ◽  
Azmizam Manie Mani ◽  
Saafie Salleh ◽  
Afishah Alias
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Low Cost ◽  
Argon Plasma ◽  
Optical Transmittance ◽  
Zno Thin Films ◽  
Plastic Substrate ◽  
Zno Films ◽  
X Ray Diffraction ◽  
X Ray

Zinc Oxide (ZnO) has attracted much attention because of its high optical transmittance approximately ~80 % with a wide band gap of (3.3 eV at 300 K) and a relatively low cost material. ZnO thin films were deposited on plastic substrate using RF powered magnetron sputtering method. The target used is ZnO disk with 99.99 % purity. The sputtering processes are carried out with argon gas that flow from 10-15 sccm. Argon is used to sputter the ZnO target because the ability of argon that can remove ZnO layer effectively by sputtering with argon plasma bombardment. The deposited ZnO thin films are characterized using X-Ray Diffraction (XRD) and UV-Vis Spectrometer. The analysis of X-ray diffraction show that good crystalline quality occurs at nominal thickness of 400 nm. The optical studies showed that all the thin films have high average transmittance of approximately 80 % and the estimated value of optical band gap is within 3.1 eV-3.3 eV range.

scholarly journals Optical Properties of Undoped and Indium-doped Tin Oxide Thin Films

2011 ◽  
Vol 35 (1) ◽  
pp. 99-111 ◽  
Author(s):  
Fatema Rezwana Chowdhury ◽  
Shamima Choudhury ◽  
Firoz Hasan ◽  
Tahmina Begum
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Tin Oxide ◽  
Optical Transmittance ◽  
Band Gap Energy ◽  
Visible Range ◽  
Absorption Region ◽  
Gap Energy ◽  
Glass Substrates ◽  
In Doping

Thin films of Tin Oxide (SnO2), having thickness of 200 nm, were formed on to glass substrates by thermal evaporation of high-purity SnO2 powder in vacuum at various substrate temperatures (TS), ranging between 25 and 200°C. SnO2 films with varying thickness were also prepared for a fixed TS = 100°C. Further, doping of SnO2 films with Indium (In) was accomplished through solid state diffusion process by successive deposition of SnO2 and In films and subsequent annealing at 200°C for 10 minutes. Both undoped and doped films were characterized optically by UV-VIS-NIR spectrophotometry in the photon wavelength ranging from 300 to 2500 nm. In the visible photon wavelength range, the average optical transmittance (T%) of the films with varying TS was found to be 85%. The maximum value of T % was found to be 89 % around the wavelength of 700nm. The variation of absorption coefficient with photon energy in the fundamental absorption region is the steepest for TS = 100°C. The sub-band gap (SBG) absorption is also minimum for this Ts. A fluctuating behavior of the band gap energy (Eg) with Ts is observed attaining the highest value of 3.59 eV for Ts = 100°C. The band gap energy increases with thickness but T% in the visible range decreases. The T% in the visible range varies inversely with indium doping, being highest for undoped films. The Eg increases upto 2 wt% In doping and gradually decreases for enhanced doping. It seems reasonable to conclude that In doping does not bring favorable optical characteristics. Undoped SnO2 films having thickness of 200 nm and formed at substrate temperature of 100°C yield essential acceptable properties for photovoltaic applications.DOI: http://dx.doi.org/10.3329/jbas.v35i1.7975Journal of Bangladesh Academy of Sciences, Vol.35, No.1, 99-111, 2011

Preparation, Microstructure and Optical Absorption Behaviour of NiO Thin Films

2008 ◽  
Vol 8 (8) ◽  
pp. 4111-4115 ◽  
Author(s):  
Amit Kumar Srivastava ◽  
Subhash Thota ◽  
Jitendra Kumar
Keyword(s):  
Thin Films ◽  
Optical Absorption ◽  
Band Gap ◽  
Annealing Temperature ◽  
Quartz Substrate ◽  
Wave Length ◽  
Average Diameter ◽  
Optical Transmittance ◽  
Dip Coating ◽  
Spherical Particles

Nickel oxide thin films have been prepared by spin coating on glass, silicon(111) and quartz substrate using a solution of nickel acetate tetrahydrate in 2-methoxyethanol and mono-ethanolamine and subsequent annealing at 300–600 °C for 2 h in air. These films have been characterized with regard to phase, microstructure and optical absorption using X-ray diffraction, atomic force microscopy and UV-visible spectrophotometry, respectively. It is shown that NiO thin films have polycrystalline nature and possess an f.c.c. (NaCl-type) structure with lattice parameter varying with annealing temperature (T) and solution molarity; typical value being a = 4.186 Å with T = 500 °C and molarity 0.5 M. The microstructure clearly reveals the formation of ellipsoids with average projected major and minor diameters as ∼58 and ∼38 nm, respectively and nano-rods of average diameter ∼12nm with aspect ratio of ∼5.2. On the other hand, thin films formed by dip coating with the same solution contain spherical particles of average diameter ∼28 nm. NiO thin films exhibit (i) high optical transmittance (80–95%) in the wave length range of 400–800 nm, (ii) sharp absorption in the interval 300–400 nm like that of semiconductor/insulator, (iii) decrease of energy band gap, Eg (value lies in the range 3.66–3.83 eV; bulk value being 3.55 eV) with increase of annealing temperature and molarity both. The higher values of band gap have been attributed to the reduced average size of the crystallites.

scholarly journals Structure, Morphology and Opto-Electrical Properties of Nanostructured Indium Doped SnO2 Thin Films Deposited by Thermal Evaporation

2016 ◽  
Vol 12 (27) ◽  
pp. 263 ◽  
Author(s):  
Md. Mahafuzur Rahaman ◽  
Kazi Md. Amjad Hussain ◽  
Mehnaz Sharmin ◽  
Chitra Das ◽  
Shamima Choudhury
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Optical Band Gap ◽  
Thermal Evaporation ◽  
High Vacuum ◽  
Optical Transmittance ◽  
Visible Range ◽  
Average Crystalline Size ◽  
Thermal Evaporation Method ◽  
Double Beam

Indium doped Tin oxide (SnO2: In) thin films of various thicknesses (200-600 nm) with fixed 2% indium (In) concentration were prepared by thermal evaporation method onto glass substrates under high vacuum (10-6 Torr). As deposited films were vacuum annealed at 200o C for 60 minutes. The structure, optical, electrical and morphology properties of SnO2: In thin films were investigated as a function of film thickness. The XRD analysis revealed that films were polycrystalline in nature with a tetragonal structure having (110) plane as the preferred orientation. The average crystalline size increased from 34.8 to 51.25 nm with increase of film thicknesses. The surface morphology of the doped films was obtained by Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscope (FESEM). Optical transmittance was obtained from a double beam UV-Vis- NIR spectrophotometer. Maximum transmittance varied from 65-76% in the visible range of the spectrum. Optical band gap (Eg) varied between 2.89 and 3.20 eV. The resistivity of SnO2: In thin films was as high as 105 Ω-cm. Activation energy of the films were found to be 0.18 to 0.47 eV for 300-600 nm film thicknesses. Due to high optical band gap and high electrical resistivity, these nanostructured films can be used in optoelectronic devices especially as opto-insulator.

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