Automatic plotter of volt-farad characteristics of semiconductor structures (C-V curve tracer)

A device for automatic recording of the C-V characteristics of semiconductor structures (SCS) is described. The operating frequencies are 1 and 10 MHz, The ranges of capacitance measurement are 1-500 pF at 10 MHz and 1-800 pF at 1MHz, the voltage scanning time for an SCS is continuously variable from 600 μsec to tens of minutes, and the maximum scanning voltage can reach hundreds of volts. Speed and sensitivity are ensured by use of a 2T-bridge as capacitance meter; by the use of two phase-sensitive feedback loops, each of which compensates for bridge unbalance caused by variations of the capacitive ωCx and active Gx components of SCS admittance, as a result of which the bridge is always balanced, i.e., in a state of maximum sensitivity; by phase detection of a signal that is proportional to Cx; and by use in the 2T-bridge of varactors to compensate for variations of Cx and Gx.