An Electron Beam Method of Measuring Resistivity Distribution in Semiconductors

Resistivity variation in Ge crystals was measured by an electron beam. Resolving power was theoretically analysed. Dimensions of the specimens were 0.4×1×2.1 mm^3 (short specimen) and 0.5×1×9.8 mm^3 (long specimen), and an ohmic electrode was soldered at each end of the specimens. A pulsed electron beam of 1 kHz irradiated the specimen and an induced voltage of a few ten μV was amplified and integrated to get the resistivity variation. Radius, current and energy of the beam were less than 7 μm, a few nA and 20-30 KeV, respectively. Diffusion lengths were also measured by the electron beam to be 30 μm (shot specimen) and 120 μm (long specimen), and the measured resistivity variation was calibrated by using the diffusion length in each specimen. Calibrated ranges of the resistivity variation of 2.5 Ωcm (short specimen) and 35 Ωcm (long specimen) agreed fairly well with the result obtained by the single-probe method.