Hot electron transport through metal–oxide–semiconductor structures studied by ballistic electron emission spectroscopy

Abstract

Study on the interface thermal stability of metal-oxide-semiconductor structures by inelastic electron tunneling spectroscopy Appl.Hot carrier transport effects in Al 2 O 3 -based metal-oxide-semiconductor structures Hot-electron transport through Au/CaF 2 /Si (111) structure studied by ballistic electron emission spectroscopy J. Appl. Phys. 85, 941 (1999); 10.1063/1.369214 Current oscillations in thin metal-oxide-semiconductor structures observed by ballistic electron emission microscopy J.The tip of a scanning tunneling microscope ͑STM͒ was used to inject electrons into thin Pt layers of metal-oxide-semiconductor ͑MOS͒ structures. The collector currents emanating from the n-type Si͑100͒ substrates were measured as a function of the electron energy, determined by the STM tip bias V T , for different oxide biases V ox applied independently across the oxide layers. The SiO 2 layers were thermally grown in a device processing line and ranged from 27 to 62 Å in thickness. A current threshold near V T ϭ3.90 V is interpreted in terms of current transport through the SiO 2 conduction band. The current transport through the MOS structure was modeled in a single band description for zero oxide thickness, and fitted to the collector currents that had been corrected for impact ionization effects in the Si. Deviations between the two curves represent the influence of the transmission probability T ox through the SiO 2 film of finite thickness. T ox can thus be determined from the experimental data. Within an eV of threshold the magnitude of T ox was observed to be particularly sensitive to small changes in oxide bias in the range 0.3 VտV ox տϪ0.1 V. The transmission probabilities were also calculated by integrating the Boltzmann equation using Monte Carlo techniques that incorporate energy dependent effective masses and electron phonon scattering rates. Agreement between the two approaches is quite good, including the observed sensitivity on oxide bias in the threshold region, which is a direct consequence of the strong electron-optical phonon scattering in the oxide. The 27 Å thick oxide structures exhibited in the ballistic electron emission microscopy images scattered patches of high transmittance of only 1-2 nm in extent. The collector currents arising from injection at these patches indicated thresholds as low as 1.1 eV, but the observed modest currents above that threshold argue against local shorts that would arise from pinholes in the oxide.

Barrier height determination of Au/Oxidized GaAs/n-GaAs using ballistic electron emission spectroscopy

“…1,2 However, the GaAs oxide interfacial layer (IL) can induce a high density of interface traps and cause Fermi-level pinning. This is similar to what was observed on some ultrathin SiO 2 based samples, 6,7 where the origin of the first threshold was thought to be related to the impurities embedded in the oxide layer or a thinner oxide underneath the probed area. Although the effects of the interfacial GaAs oxide on the growth and performance of high-j dielectrics grown on GaAs have been explored, 3 there is a lack of detailed work reporting the energy barriers of the oxidized GaAs.…”

Hot carrier transport effects in Al2O3-based metal-oxide-semiconductor structures

“…20 V th was determined from computer fits to the data using a model calculation of the dependence of the collector current I c on the tip bias V T in the immediate threshold region. Differences in V th of less than 50 meV were noted in the results calculated with models that either exclude 21 or included 22 quantum mechanical effects in the transmission probabilities. In our determinations of V th we included them.…”

Ballistic-electron-emission-microscopy studies onAu/SiO2/n-type Si(100) andQuattropani1, Maggio-Aprile2, Niedermann3 et al. 1998Phys. Rev. B20130View full textAdd to dashboardCite

“…Leakage currents have also been observed by Ludeke, Bauer, and Cartier. 5 In their case, they appeared in certain defect regions possibly related to impurities embedded in the oxide. In our measurements, this leakage current is never very intense ͓spectrum ͑d͒ in Fig.…”