The Keithley Model 530 Type-All System is an electronic system designed for measurement of resistivity and determination of conductivity type of a semiconductor. The Keithley System contains a precision current source, digital microvoltmeter, and other circuitry needed for resistivity and typing determinations. The Model 530 must be used with a standard four-point in-line probe to make contact to the sample. RESISTIVITY MEASUREMENT. Resistivity of a semiconductor material can be easily determined by applying a known current through the sample. The resultant voltage drop across the sample Is then measured using a sensitive microvoltmeter. However, since the resistivity is a function of slice geometry and probe spacing, several correction factors must be used. These correction factors are explained In ASTM Designation: F84-70*. The basic factors which need to be considered are: Slice diameter D mm Average probe separation S mm Specimen thickness W mm NOTE: All dimensions are assumed to be in metric units unless otherwise specified. The Keithley Model 530 System provides the convenience of selectable current so that the voltage reading can be scaled to read directly in terms of OHM-CM (where 1 mV = 1 OHM-CM). A computer program and printout are provided in the Appendix of this Instruction Manual for calculating the proper current using BASIC language.