Experimental investigation of transition from Fowler–Nordheim field emission to space-charge-limited flows in a nanogap

An experimental investigation of the transition from Fowler–Nordheim (FN) field emission to space-charge-limited (SCL) flows in a nanogap is presented. Electrodes with gap size D∼30–70 nm corresponding to D/λo up to a maximum of ∼2×103, where λo is the de Broglie wavelength of the space-charge-electrons, are experimented. The transition from the FN field emission to the classical SCL flow is a function of the applied bias and lies in the range 5–15 V. The equilibrium transmitted current density for the 50 nm sample indicates a transition from the FN to the quantum SCL flow at ∼0.4 V with D/λo of ∼35 and then gradually to the classical SCL behavior as the voltage is increased beyond ∼9 V. The experiments indicate no sharp demarcation between the different regimes.