Keithley RampRate QuasiCVAppNote1 free download

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Number 2973 Application Note Using the Ramp Rate Method for Making Series Quasistatic C-V Measurements with the Model 4200-SCS Semiconductor Characterization System Introduction I Capacitor Capacitance-voltage (C-V) measurements are generally made using an AC measurement technique. However, some capacitance Force HI Force HI measurement applications require a DC measurement technique. These are called quasistatic C-V (or QSCV) measurements because they are performed at a very low test frequency, that is, A almost DC. These measurements usually involve stepping a DC voltage and measuring the resulting current or charge. Some of V the techniques used for quasistatic C-V measurements include the feedback charge method and the linear ramp method. The Model 4200-SCS Semiconductor Characterization System uses a new method, the ramp rate method, which employs two Model 4200-SMUs Source-Measure Units (SMUs) with two Model Force LO 4200-PA PreAmps. The optional 4200-PA PreAmps are required internally connected because this test involves sourcing and measuring current in SMU1 SMU2 the picoamp range. The SMUs are used to source current to ForceSMU MeasureSMU charge the capacitor, and then to measure the voltage, time, and discharge current. Figure 1. Connections for Capacitance Measurements Using Ramp Rate Method The software calculates the capacitance as a function of voltage from the measured parameters and shows the curve on dQ C =