THERMIONIC REVERSE CURRENT IN GAAS SURFACE-BARRIER STRUCTURES

Surface-barrier structures were formed by chemical deposition of Ni on the surface of n-type GaAs [n = (1-2) x 10(15) cm-3 at 300 K]. At low voltages (1-10 V) and elevated temperatures (450-550 K) the reverse current was due to thermionic emission (the current could be described by the Bethe theory allowing for the image forces). The Richardson constant [(8.2 +/- 1.0) A.cm-2.K-2] found from the temperature dependence of the reverse current agreed with the value deduced from the temperature dependence of the forward current and with the value expected theoretically for GaAs. The height of the potential barrier deduced from the temperature dependence of the reverse current (0.96 V at 0 K) was in agreement with the values obtained from the temperature dependences of the forward current and of the barrier capacitance.