INELASTIC ELECTRON-TUNNELING SPECTROMETER FOR COMPLETE CALIBRATED MEASUREMENTS OF ANY 2 OR 4 TERMINAL JUNCTIONS

The conventional tunneling spectrometer gives the uncalibrated second derivative d2V/dI2 versus applied voltage (V) of the junction current-voltage curve (I-V). However, the calibrated second derivative d2I/dV2 is more useful for accurate comparison with theory and can be applied to negative resistance devices. We report here a single electronic instrument for calibrated measurements of all relevant tunneling junction parameters, i.e., dynamic conductance (G), dynamic capacitance (C), current-voltage curve, and its first and second calibrated derivatives. Moreover, it can measure the derivative of the dynamic capacitance (dC/dV) versus applied potential, which is useful for various types of semiconductor devices. This design is versatile enough to find many laboratory applications where current-voltage curves are of interest. The circuit, based on a simple design, is accurate to 1% and allows spectral acquisition in about 15 min.