The MX 601 measures the specific resistance of  semi-insulating wafers like Gallium Arsenide.

It is not necessary to prepare a wafer for measuring, it is just placed on a hardcoated table and the cover is closed to keep out light. The wafer is chucked down by vacuum to effectively avoid piezo-electric effects.The vacuum is generated via a converter so that only a regular compressed air supply is required. A PC evaluates the data and then calculates and outputs the results. Using a computer has the added advantage that the calibration constants can be accessed, the output type can be changed, and statistical  programs can be added.