Moderately-doped Schottky barriers: a description using thermionic emission over a wide temperature range

Abstract

We report on a low temperature study of Schottky barriers between Au, Cr or Al electrodes deposited directly onto moderately-doped Si or GaAs substrates with doping densities in the range cm−3 and find the unexpected result that for temperatures 150 K both the zero-voltage Schottky barrier height, and the reciprocal ideality factor, , have linear temperature dependences that extrapolate to zero at T = 0. Accordingly, the thermionic emission equation with these modified temperature-dependent parameters gives a good description of the current–voltage (I–V) characteristics at temperatures where thermionic field emission and field emission (direct tunneling) in addition to thermionic emission are known to be important. Our analysis utilizes a barrier inhomogeneity model to show that the temperature-independent product determined from forward bias characteristics defines a flat band voltage which is shown to be equivalent to the built-in voltage separately determined by extrapolation of capacitance versus voltage measurements made in the reverse bias region.