P. Prathap

Influence of sulfurization temperature on physical properties of Cu2ZnSnS4 thin films

Copper Zinc Tin Sulfide (Cu2ZnSnS4 or CZTS) is gaining much attention recently as a potential light absorber alternative to CuInGaSe2 due to its suitable energy band gap ∼1.5 eV with p-type conductivity, high optical absorption coefficient of ∼105 cm−1. Moreover, all its constituents are abundant in the crust of the earth and environmentally harmless. In the present investigation, CZTS thin films were prepared using simple two step process of, sulfurization of sequentially sputtered stack, Glass/Zn/Sn/Cu (hereafter CTZ) metallic precursors on soda lime glass substrate held at temperature 200 °C. The sputter power was optimized individually for Zn, Sn, and Cu layers. The sputtered CTZ precursors were annealed at different temperatures in the range, 300–550 °C with an increment of 50 °C for 2 h in the ambience of vaporized elemental sulfur. The XRD pattern revealed that the films sulfurized in the temperature range 300–400 °C showed various spurious (binary and ternary) phases and the films sulfurized at 45...

Laser doping from spin-on sources for selective emitter silicon solar cells

Development of laser doping process for the formation of a selective emitter (SE) for p-type and n-type silicon solar cells is presented. The SE is formed by laser doping of spin-on dopant sources using an intermediate barrier layer (BL). The BL serves to form shallow emitter and also offers advantage to avoid etch back step. The shallow emitter is formed by applying a controlled thermal diffusion step, which in turn reduces the laser induced defects in the SE. This process has an advantage that the shallow and selective emitters can be formed from a single dopant source. In this investigation, PECVD deposited SiOx was used as the barrier. KrF excimer laser at 248 nm was used for the selective doping. The dopant concentration and depth, as measured by SIMS, were controlled by variation of the laser parameters and barrier thickness. It was found relatively lower thickness PECVD deposited SiOx barrier layer with high dopant content in the spin-on layer at comparably low laser fluences resulted in the best electrical results. The SiOx layers acted as perfect barrier for the boron diffusion. It was also observed that multiple laser annealing above a threshold laser fluence resulted in the redistribution of the dopant along with deepening of selective emitter because of the limitedness of the dopant source. Also, this is attributed to the increase of the total absorbed energy by the successive laser pulses. The results were discussed and presented in detail.

Laser processing for thin film crystalline silicon solar cells

Laser processing applied to thin film silicon is an interesting approach for solar cell fabrication. In this work, we investigate the effects of a continuous wavelength (CW) laser irradiation in solid phase or liquid phase of silicon on the structural and electrical properties of thin film silicon layers. Thus, results on CW laser induced crystallisation (LIC) of ultrathin amorphous silicon, laser induced epitaxy (LIE) of a thick amorphous silicon on a seed silicon layer, and laser induced thermal annealing (LIA) of polycrystalline silicon films are presented and discussed.

Raman, Magnetic and Electrical Properties of Sprayed Zn1−xMnxO Films

Zn1−xMnxO films have been synthesized by spray pyrolysis at a substrate temperature of 400 °C with different manganese compositions that vary in the range, 0.0≤x≤0.25, on corning 7059 glass substrates. The as‐grown layers were characterized to evaluate the structure, magnetic and electrical properties. Raman spectroscopy studies revealed that Mn2+ ions were substituted for Zn2+ into the ZnO matrix. All the films showed ferromagnetic behavior at a temperature of 10 K and exhibited n‐type electrical conductivity. The electrical resistivity decreased with the increase of Mn‐content.