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In this study, Cu(In,Ga)Se2 (CIGS) absorber is grown on Mo-coated soda-lime glass substrates through co-evaporation deposition. Several types of Ga distribution in CIGS was examined by adjusting the [Ga]/([In]+[Ga]) ratio at the first and third stages. The electrical properties of the film were also determined. The carrier concentration increased with increasing Ga content. The highest carrier concentration of 8.46 × 1015 cm−3 were obtained when the [Ga]/([In]+[Ga]) ratio (0.36) was 0.4: 0.3 at the first and third stage. The best device conversion efficiency of 12.5% was achieved because the suitable [Ga]/([In]+[Ga] ratio, band-gap gradient distribution and low recombination rate.

Fluid flow and heat transfer during dual-beam laser welding have been investigated with a view to controlling flow in the weld pool and the resulting weld pool geometry and surface deformation. The investigation is based on a transient two-dimensional finite volume numerical simulation of flow in a moving plate for a dual heat source. Each of the two laser beams at the top surface of the weld pool is modeled as a Gaussian source. The heat transfer mechanisms considered includec onduction in the solid region, as well as natural and Marangoni convection in the liquid region. The convection patterns induced by the Marangoni convection in the liquid region are altered by imposing a second laser beam, thereby affecting the flow structure. This paper examines the validity of the numerical simulation by observing the wed pool geometry experimentally. Both the power levels and inter-beam spacings are varied and the material used is AISI 304 stainless steel. Representative results of the flow patterns in the weld pool for the dual-beam laser welding process are reported.Fluid flow and heat transfer during dual-beam laser welding have been investigated with a view to controlling flow in the weld pool and the resulting weld pool geometry and surface deformation. The investigation is based on a transient two-dimensional finite volume numerical simulation of flow in a moving plate for a dual heat source. Each of the two laser beams at the top surface of the weld pool is modeled as a Gaussian source. The heat transfer mechanisms considered includec onduction in the solid region, as well as natural and Marangoni convection in the liquid region. The convection patterns induced by the Marangoni convection in the liquid region are altered by imposing a second laser beam, thereby affecting the flow structure. This paper examines the validity of the numerical simulation by observing the wed pool geometry experimentally. Both the power levels and inter-beam spacings are varied and the material used is AISI 304 stainless steel. Representative results of the flow patterns in the weld ...

Fluid flow and heat transfer during dual-beam laser welding is analyzed. The objective of this investigation is control of flow in the weld pool and its impact on the resultant weld pool geometry and solidification. It is based on a transient two-dimensional finite volume numerical simulation of flow in a moving plate for a dual heat source. Each of the two laser beams at the top surface of the weld pool is modeled as a Gaussian source. The heat transfer mechanisms considered include conduction in the solid region, natural and Marangoni convection in the liquid region. The change in the fluid flow structure induced by imposing a second laser beam affects the weld pool shape. The pool geometry, temperature, and velocity fields that result during dual-beam laser welding are compared with those of a single beam laser welding process for different inter-beam spacings and surface tension temperature coefficients for stainless steel 304. Representative results of the flow and temperature distribution in the weld pool for the single and dual-beam laser welding processes are reported graphically in the form of liquid phase isotherm, stream functions and velocity vectors at specified times.Fluid flow and heat transfer during dual-beam laser welding is analyzed. The objective of this investigation is control of flow in the weld pool and its impact on the resultant weld pool geometry and solidification. It is based on a transient two-dimensional finite volume numerical simulation of flow in a moving plate for a dual heat source. Each of the two laser beams at the top surface of the weld pool is modeled as a Gaussian source. The heat transfer mechanisms considered include conduction in the solid region, natural and Marangoni convection in the liquid region. The change in the fluid flow structure induced by imposing a second laser beam affects the weld pool shape. The pool geometry, temperature, and velocity fields that result during dual-beam laser welding are compared with those of a single beam laser welding process for different inter-beam spacings and surface tension temperature coefficients for stainless steel 304. Representative results of the flow and temperature distribution in the wel...