OPTICAL ABSORPTION IN AMORPHOUS THIN FILMS OF SnO2 DEPOSITED BY THERMAL EVAPORATION

2007 ◽  
Vol 21 (12) ◽  
pp. 2017-2032 ◽  
Author(s):  
M. ANWAR ◽  
S. A. SIDDIQI ◽  
I. M. GHAURI
Keyword(s):  
Thin Films ◽  
Optical Absorption ◽  
Film Thickness ◽  
Substrate Temperature ◽  
Band Gap ◽  
Optical Band Gap ◽  
Fundamental Absorption Edge ◽  
Outward Diffusion ◽  
Optical Energy ◽  
Amorphous Thin Films

The fundamental absorption edge of SnO 2 amorphous thin films has been investigated. It has been observed that the optical energy gap decreases with the increase in film thickness, substrate temperature and post deposition annealing. The results are analysed by assuming optical absorption by non-direct transition. The decrease in optical band gap with increase in film thickness may be interpreted in terms of the incorporation of oxygen vacancies in the SnO 2 lattice. The decrease in optical energy due to the increase in substrate temperature may be ascribed to the release of trapped electrons by thermal energy or by the outward diffusion of the oxygen-ion vacancies, which are quite mobile even at low temperatures. The decrease in optical band gap due to annealing may be due to the formation of tin species of lower oxidation state.

scholarly journals Correlation of film thickness to optical band gap of Sol-gel derived Ba0.9Gd0.1TiO3 thin films for optoelectronic applications

2017 ◽  
Vol 162 ◽  
pp. 01042
Author(s):  
Yen Chin Teh ◽  
Ala’eddin A. Saif ◽  
Zul Azhar Zahid Jamal ◽  
Prabakaran Poopalan
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Band Gap ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Optoelectronic Applications

BAND GAP SHIFT DUE TO NITROGEN DOPING, COMPOSITION GAS PRESSURE AND MICROWAVE POWER OF a-C:N THIN FILMS GROWN BY NEWLY-DEVELOPED SURFACE WAVE MICROWAVE PLASMA CVD

2004 ◽  
Vol 11 (06) ◽  
pp. 559-562
Author(s):  
M. RUSOP ◽  
S. ADHIKARI ◽  
A. M. M. OMER ◽  
S. ADHIKARY ◽  
H. UCHIDA ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Wave ◽  
Film Thickness ◽  
Band Gap ◽  
Microwave Power ◽  
Annealing Temperature ◽  
Optical Band Gap ◽  
Microwave Plasma ◽  
Gas Pressure ◽  
Developed Surface

This paper reports the band gap shifting due to nitrogen ( N 2) doping, microwave power and composition gas pressure of nitrogenated amorphous carbon ( a - C : N ) thin films deposited by newly-developed surface wave microwave plasma chemical vapor deposition (SWMP-CVD). Results show that the optical band gap decreased from 4.1 eV to 2.4 eV corresponding to the increase of N 2 doping from 0 to 5% in the gas ratio. However, further increase of N 2 doping beyond 5% did not decrease the band gap. It was found that composition gas pressure and launched MW power during film deposition also largely control the optical band gap. Investigation of annealing effects on optical band gap and film thickness of the N 2 doped films revealed that both band gap and film thickness decrease significantly with increase of annealing temperature. The optical band gap decreased from 2.4 eV to 1.1 eV, while film thickness decreases from 320 nm to 50 nm corresponding to 200 to 400°C annealing temperature. The results revealed that the properties of a - C : N can be tuned by changing the annealing temperature, composition gas pressure and microwave power of the SWMP-CVD system.

Optical Investigation of Bi2O3-B2O3 Glass System

2010 ◽  
Vol 93-94 ◽  
pp. 336-339 ◽  
Author(s):  
Kitipun Boonin ◽  
Jakrapong Kaewkhao ◽  
Pichet Limsuwan
Keyword(s):  
Optical Absorption ◽  
Band Gap ◽  
Absorption Spectra ◽  
Wavelength Range ◽  
Absorption Edge ◽  
Optical Band Gap ◽  
Fundamental Absorption Edge ◽  
Optical Investigation ◽  
Optical Absorption Spectra ◽  
Molar Volumes

Glasses with composition xBi2O3:(100-x)B2O3 with 30x70 (in mol%) have been prepared using the normal melt-quench technique and investigated their properties. The optical absorption spectra of the glasses have been measured in the wavelength range 400-700 nm. It has been found that, the fundamental absorption edge has been identified from the optical absorption spectra. The values of optical band gap were decreased and the molar volumes were increased, with the addition of Bi2O3, due to the formulation of non-bridging oxygen (NBOs).

Effect of stress on optical band gap of ZnO thin films with substrate temperature by spray pyrolysis

2009 ◽  
Vol 485 (1-2) ◽  
pp. 413-417 ◽  
Author(s):  
T. Prasada Rao ◽  
M.C. Santhosh Kumar ◽  
S. Anbumozhi Angayarkanni ◽  
M. Ashok
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Band Gap ◽  
Spray Pyrolysis ◽  
Optical Band Gap ◽  
Zno Thin Films

Influence of Nano Filler (ZrO2) on Optical and Thermal Studies of Potassium Doped Polyethylene Oxide Solid Polymer Electrolytes

2022 ◽  
Vol 1048 ◽  
pp. 101-109
Author(s):  
Suresh Sripada ◽  
M. Chandrashekhar Reddy ◽  
T. Sreekanth ◽  
Rajesh Siripuram ◽  
K. Venkateshwarlu
Keyword(s):  
Optical Absorption ◽  
Band Gap ◽  
Polymer Electrolyte ◽  
Polyethylene Oxide ◽  
Polymer Electrolytes ◽  
Optical Band Gap ◽  
Thermal Studies ◽  
Fundamental Absorption Edge ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer

Solid polymer electrolyte films made with potassium doped Polyethylene oxide using ZrO2 as nanofiller (70PEO-30KBF4-x ZrO2 where x = 1, 2.5, 5, 7.5, & 10 wt% ­­) were prepared by solution casting technique. Optical and thermal properties of polymer electrolyte films were studied by using Optical absorption and DSC techniques. From Optical absorption spectra, it is observed that fundamental absorption edge is shifted towards the higher wavelength side (range 259- 297 nm) with increase of nano filler (ZrO­2) concentration (1-10 wt %). Optical band gap for all electronic transitions (p=1/2, 2, 2/3 and 1/3) are found to be increased as incorporation of nano filler (ZrO2) which confirms the structural rearrangements takes place in polymer electrolyte films. Optical band gap for indirect allowed transitions (p=1/2) are found to be in the range of 1.93-3.34eV. Decrease in Urbach energy (4.8eV- 1.4eV) is associated with decrease in defect formation in host polymeric matrix (PEO-KBF4) as a result of embedded nano filler (ZrO2). DSC spectra analysis of polymer electrolytes has showed melting temperatures in the range 63.63-73.71°C and highest crystallinity is found to be 85 % (10 wt % ZrO­2). Enthalpy values are elevated with increase in nanofiller composition (ZrO2) in the present polymer electrolyte films.Keywords: PEO based polymer electrolytes, Solid polymer electrolytes, Optical and Thermal studies.

DC CONDUCTION MECHANISMS IN AMORPHOUS THIN FILMS OF MIXED OXIDES In2O3–SnO2 SYSTEM DEPOSITED BY CO-EVAPORATION

2006 ◽  
Vol 20 (15) ◽  
pp. 2159-2174 ◽  
Author(s):  
M. ANWAR ◽  
S. A. SIDDIQI ◽  
I. M. GHAURI
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Film Thickness ◽  
Substrate Temperature ◽  
Oxidation State ◽  
Dielectric Constants ◽  
Amorphous Thin Films ◽  
Conduction Mechanisms ◽  
Free Band ◽  
Band Conduction

A discussion of dc conduction mechanisms in thermally co-evaporated amorphous thin films of Al – In 2 O 3– SnO 2– Al structure is presented. Composition (in molar %), film thickness, substrate temperature, and post deposition annealing have profound effects on the electrical properties of the films. The effects of temperature on the I – V characteristics and electrical conductivity of Al – In 2 O 3– SnO 2– Al structure are also reported. The values of dielectric constants estimated by capacitance measurements suggest that high-field conduction mechanism is predominantly of Poole–Frenkel type. At low temperature and low field the electron hopping process dominates but at higher temperature the conduction takes place by transport in the extended states (free-band conduction). The transition from hopping to free band conduction is due to overlapping of localized levels and the free band. The increase in the formation of ionized donors with increase in temperature during electrical measurements indicates that electronic part of the conductivity is higher than the ionic part. The initial increase in conductivity with increase in Sn content in In 2 O 3 lattice is caused by the Sn atom substitution of In atom, giving out one extra electron. The decrease in electrical conductivity above the critical Sn content (10 mol % SnO 2) is caused by the defects formed by Sn atoms, which act as carrier traps rather than electron donors. The increase in electrical conductivity with film thickness is caused by the increase in free carriers density, which is generated by oxygen vacancy acting as two electrons donor. The increase in conductivity with substrate temperature and annealing is due either to the severe deficiency of oxygen, which deteriorates the film properties and reduces the mobility of the carriers or to the diffusion of Sn atoms from interstitial locations into the In cation sites and formation of indium species of lower valence state so that the In 3+ oxidation state may be changed to the In 2+ oxidation state.

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