Research on Properties of the Inverted Index for Photodetector Barrier Layer Capacitance

For the design of high-speed photodetector, to reduce the junction capacitance C_j and study the relationship between C_j and reverse bias U_B of the phototube is very important. Through substitution measurement of a group of standard capacitors, the function relationship of measuring voltage and capacitance has been established, and with the method of interpolation and least squares, the inverted exponential curve of junction capacitance and bias is obtained. Regression analysis demonstrates: For HFD1060 photodiode, the purpose that to effectively reduce junction capacitance can be easily achieved if bias ranges from 10 V to 15 V, and almost no change when U_B is over 15 V. This method overcomes the effects of stray capacitance and circuit noise to measuring precision, which is mainly decided by the precision of standard capacitors.