Design and experimental characteristics of n-Si/CaF2/Au hot electron emitter for use in scanning hot electron microscopy

For scanning hot electron microscopy experiments, n-Si/CaF2/Au hot electron emitters were designed and fabricated to characterize the emission properties. A self-consistent method was used in analyzing the hut electron energy and the tunneling current density while considering the quantum mechanical effects in the space-charge region. By comparison of the theoretical calculations with the experimental results for current density, the tunneling electron effective mass of CaF2 is estimated to be about 0.3m(0). This material structure can provide an electron current density of more than 10 A/cm(2) at the hot electron energies of 2.9 eV or 3.7 eV by selecting the thickness of CaF2 to be 3 nm or 4 nm, respectively, for the electron density of 8 x 10(19) cm(-3),or at 3.2 eV or 3.4 eV by selecting the electron density of 10(19) cm(-3) or 2 x 10(18) cm(-3), respectively, for the insulator thickness of 3 nm.