FABRICATION AND CHARACTERISATION OF CW CO2 LASER FOR ITO STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES IMPROVEMENT

FABRICATION AND CHARACTERISATION OF CW CO2 LASER FOR ITO STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES IMPROVEMENT

 

ABSTRACT

 

The objectives of this study are design; construction and operation of the continuous wave CO2 laser system and its characterisation the effecting parameters pressure, current, and temperature on laser output power are discussed. The CW CO2 laser system parameters were (10 KV) voltage, current (18 mA) and (6 mbar) pressure of the gaseous mixture. It has a mix of gases of (CO2, N2, He) in a ratio of (10%, 10%, and 80%), respectively. The cooling water temperature was (5). It was found that these parameters are the optimum to get the highest value for the CW CO2 laser system, which reached (54 watts), and the efficiency of this CW CO2 laser system reached (30%). CW CO2 lasers, among the most efficient and powerful of all lasers, have many applications in industrial and medical fields. The properties of indium tin oxide (ITO) thin films strongly depend on the temperature preparation condition, so we suggest using a CW CO2 laser beam for indium tin oxide (ITO) thin film annealing and study the effects on the structural, optical and electrical properties of thin film. ITO thin films are deposited on glass substrates by sputter coater system (RF) from a high density target (In2O3-SnO2, 90-10 wt%). The base pressure of the chamber was 10−7 mbar. The ITO thin films have been prepared at power values 100W. After deposition, ITO thin films have been irradiated by CW CO2 laser (λ=10.6μm). These films were annealed at different temperatures 250, 350 and 450 using laser power 13W, 19W and 25W respectively in the air for 20 minutes.

On the other hand, study the effects of annealing using the conventional method (heat furnace) on the structural, optical and electrical properties of ITO thin film at different temperatures 250, 350, 450 and 550. It was done for 1 hour in the air, and then comparison of annealing between a CW CO2 laser and the heat furnace using different ITO thicknesses of 200 nm and 400 nm. It was found that the annealing technique using the CW CO2 laser is superior to using the heat furnace. It was found that the highest average

optical transmission was 90.198.2 (%) and the energy gap was 3.81eV at thickness 200 nm using CW CO2 laser, and the highest grain size was 43.94 nm, the roughness was 4.92nm, the lower resistivity was 2.9x10-4 Ω.cm and the lower sheet resistance was 7.3Ω/sq at thickness 400 nm using CW CO2 laser.