Solar cell analysis system

Capacitance-Voltage

The base doping can be determined from the plot of 1/C² versus voltage. The width of the space charge region of a silicon solar cell, W_j, depends on the base doping concentration and can be varied with an applied reverse voltage. The solar cell's capacitance is inversely proportional to W_j and can be measured from the phase and magnitude of the AC current that results when applying a sine modulated reverse voltage.

The base doping concentration must be known for

• the calculation of base contribution to saturation current J_0,base
• the calculation of base contribution to series resistance
• estimating the current limit for small local shunts due to spreading resistance in the base.