The mercury probe is a precision instrument that facilitates rapid, convenient, and non-destructive characterization of semiconductor samples. Such probe can contact a semiconductor wafer with mercury to form a dot and a ring contact of well-defined area. The mercury probe may be used with oxidized semiconductor wafers as a gate to form a metal/oxide/semiconductor test structure for rapid insulator characterization (Capacitance vs Voltage or Capacitance vs Frequency), or it may used to form a Schottky barrier directly on a semiconductor for resistivity measurements. The mercury probe eliminates time-consuming metallization previously required for these measurements. The mercury probe may be used in a number of novel measurement configurations because of its mercury ring contact. The ring contact may act as the substrate contact for measurements of samples on semi-insulating substrates, and for oxidized samples without need for backside preparation. The mercury probe can be used with any semiconductor or insulator that does not react with mercury