Measurement of semiconductor junction parameters using lock-in amplifiers

A phase-sensitive detection scheme is described that allows the equivalent circuit of semiconductor diodes to be determined over a wide range of operating conditions. Under reverse bias, a direct plot may be obtained of the bias dependence of the exhaustion region width through impedance measurements. In the forward sense, the diode admittance may be measured even when large currents are flowing through the diode. The capability of the method, both to yield valuable information regarding physical conditions at the junction of the device and to give insight into the charge-transport mechanisms at the interface, is illustrated through a series of measurements on selenium rectifiers.