The quality of the silicon crystal determines the maximum achievable conversion efficiency of the final photovoltaic device. Thus, the quality control of the as-grown Si crystals is crucial to stabilize the manufacturing of modern Si solar cells. Semilab offers various solutions to control all the important material parameters in both multi- and monocrystalline silicon ingots.
Resistivity of the mono and multicrystalline ingots is tested by using eddy current sensor, integrated into various system platforms.
Metallic contamination and extended crystal defects are detected by using different versions of PhotoConductance Decay and Photoluminescence methods.
Finally, our Infrared Imaging system localizes the larger precipitations in the crystal in order to prevent the failures in the wire sawing process.
The operation of the P/N Tester is based on the SPV (Surface Photovoltage) technique. The excitation is represented by chopped light, which periodically generates free carriers (electron-hole pairs) in large concentration. A high sensitivity probe is capacitively coupled to the sample close to the sample surface. The surface potential barrier of the sample is periodically changed by the chopped light and can be measured by the p/n probe. When the light is on, the sample is near to the flat-band condition. When the light is off, the sample has a larger surface potential barrier. The signal stands for the difference between the potential values measured during the bright and the dark periods of the excitation. Since the sign of the signal depends on the conduction type of the sample, this method can be used for conduction type determination.
The technique has certain limitations:
PN tools are off-line, discrete point measurements suitable for feedstock or reclaim material. The easy handling is guaranteed by handheld, portable and table-top constructions.
PN-100 is a fast, easy-to-use, non-contact tool for determining conductivity type (p or n) of the semiconductor materials.
Features and System specifications: