Standard solar cell preparation

How to make a solar cell?

The fabrication of this solar cell design comprises these general steps: a. Surface preparation by cleaning and texturing to minimize light reflection. b. Diffusing an n-type dopant into the p-type wafer to form a pn junction. Back passivation through a BSF formed by Al diffusion.

What is a solar cell fabrication process?

A solar cell fabrication process uses several high-temperature steps including a phosphorus diffusion process and a metal contact firing. The silicon wafer is p-type doped to 1 · 10 15 cm −3. The required surface doping and depth for the diffused part of the pn junction are 1 · 10 19 cm −3 and 200 nm, respectively.

How do you make a wafer for a solar cell?

Wafer preparation Once the monocrystalline or multicrystalline ingots are fabricated, they must be shaped and sawed into wafers for subsequent solar cell fabrication. This process implies a material loss. First, the head and tail of the ingot are discarded, and the ingot is given a square shape by cutting off the edges.

Why do solar cells need to be doped?

Crystalline silicon needs to be doped to achieve the appropriate electrical resistivity value for the solar cells. This is achieved by adding the dopant elements to the melt. The most common p-type dopant today is Ga, but B and Al are also used.

Why do solar cells need to be purified?

To minimize recombination of carriers and attain high efficiencies, the purity of the semiconductor material used in solar cells must be very high. Therefore, silicon must be purified to fabricate solar cells. The target purity, solar grade (SoG), is lower than the so-called electronic grade (EG) used for microelectronics.

Why do solar cells use gettering process?

Hence, the gettering process further purifies the silicon wafer. This gives room for using lower quality (and lower cost) silicon material to fabricate the wafers, knowing that they will be further purified during the solar cell fabrication.