Method of Fabricating Silicon Nanowire Solar Cell Device Having Upgraded Metallurgical Grade Silicon Substrate

A method of fabricating a silicon nanowire (SiNW) solar cell device having an upgraded metallurgical grade (UMG) silicon (Si) substrate, the method comprising:

• obtaining a UMG Si plate as a substrate, said UMG Si plate having a purity lower than 99.999% (5N) and a thickness not thicker than 200 micrometers (μm);
• cleaning a surface of said UMG Si plate;
• placing said UMG Si plate into an electron-gun (e-gun) evaporation equipment to obtain a nickel (Ni) metal thin film covering said surface of said UMG Si plate;
• heating up said UMG Si plate covered with said Ni metal thin film in a reaction chamber of an atmospheric pressure chemical vapor deposition (APCVD) equipment to obtain a nickel-silicon (Ni—Si) liquid phase alloy with said Ni metal thin film and said UMG Si plate, forming said Ni—Si liquid phase alloy having teardrop-shaped drops, at least some of said teardrop-shaped drops of said Ni—Si liquid phase alloy being distributed on a surface of said UMG Si plate and each of the teardrop-shaped drops of said Ni—Si liquid phase alloy having a nanometer scale;
• obtaining disilane (Si2H6) for a SiNW process with hydrogen (H2) as a carrier gas and providing a doping gas to obtain SiNWs on said surface of said UMG Si plate that has the at least some teardrop-shaped drops of said Ni—Si liquid phase alloy, each of said SiNWs being started from a respective teardrop-shaped drop of said Ni—Si liquid phase alloy;
• providing another doping gas to obtain a thin film on an outside surface of each of said SiNWs to obtain a positive-negative (P-N) junction;
• and
• sequentially, obtaining a transparent conductive electrode through a sputtering deposition process and then processing a screen printing to obtain a front contact of silver paste and a back contact of aluminum paste.