**3.5 Rapid crystallization of amorphous silicon for thin-film silicon solar cell**

The novel crystallization technique for synthesizing crystalline Si film from a-Si film utilizing a VHF thermal micro-plasma jet is used as shown in **Figure 2** [37]. **Figure 3** shows the photocurrent–voltage characteristics and collection efficiency for p–i–n Si thin-film solar cells with crystallized Si films as an intrinsic layer [37].

**Figure 2.**

*Rapid crystallization of amorphous silicon utilizing a very-high-frequency micro-plasma jet.*

#### **Figure 3.**

*(a) Photocurrent–voltage characteristics, (b) collection efficiencies spectra of solar cells [adapted from [37] with permission].*

**429**

**Figure 4.**

*Advanced Laser Processing towards Solar Cells Fabrication*

The laser modified surface and the nature of dopants and defects in the crystalline grains are crucial to improve the performance of solar cells. Pulsed-laser hyper doping & surface texturing for photovoltaics, laser processing for thinfilm (TF) photovoltaic, Light trapping for thin silicon solar cells by Femtosecond Laser Texturing, Patterning of Transparent Conducting Oxide (TCO) layers by Femtosecond Laser as well Solar cells based on laser-modified materials are dis-

**4.1 Pulsed-laser hyper doping and surface texturing for photovoltaics**

The two different approaches eg. pulsed-laser hyper-doping and surface texturing are used to enhance photon absorption enhancement from the pulsedlaser processing of semiconductors with nanosecond, picosecond, or femtosecond laser pulses. The absorptance *A* is obtained from the expression *A* = 1–*R–T*, where *R* and *T* are reflectance and transmittance, respectively, measured with an integrating sphere to collect both specular and diffuse light. **Figure 4a** shows the untreated crystalline silicon (c-Si) which has negligible absorption of light with a wavelength longer than 1.1 μm due to its energy bandgap. **Figure 4b** shows the pulsed-laser hyper-doping with sulfur enables absorption of sub-bandgap light. **Figure 4c** shows the pulsed laser texturing that enhances above-bandgap light absorption with geometric light trapping. **Figure 4d** shows the broadband nearunity absorption is achieved with both pulsed-laser hyper-doping and surface

*(a) Untreated crystalline silicon (c-Si), (b) pulsed-laser hyper-doping with sulfur, (c) pulsed laser texturing,* 

*(d) both pulsed-laser hyper-doping and surface texturing (adapted from [31] with permission).*

*DOI: http://dx.doi.org/10.5772/intechopen.94583*

**4. Laser processing for photovoltaics**

cussed in the following section.

texturing.
