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Electrical transport in ultrathin Metal-insulator-semiconductor (MIS) tunnel junctions is analyzed using the temperature dependence of current density and admittance characteristics, as illustrated by Hg//C12H25 - n Si junctions incorporating n-alkyl molecular layers (1.45 nm thick) covalently bonded to Si(111). The voltage partition is obtained from J(V, T) characteristics, over eight decades in current. In the low forward bias regime (0.2-0.4 V) governed by thermionic emission, the observed linear T-dependence of the effective barrier height, q[uppercase_phi_synonym]EFF(T)=q[uppercase_phi_synonym]B+(kT)β0dT, provides the tunnel barrier attenuation, exp(-β0dT), with β0= 0.93 Å-1 and the thermionic emission barrier height, [uppercase_phi_synonym]B=0.53 eV. In the high-forward-bias regime (0.5-2.0 V), the bias dependence of the tunnel barrier transparency, approximated by a modified Simmons model for a rectangular tunnel barrier, provides the tunnel barrier height, [uppercase_phi_synonym]T=0.5 eV; the fitted prefactor value, G0 = 10-10 Ω-1, is four decades smaller than the theoretical Simmons prefactor for MIM structures. The density distribution of defects localized at the C12H25 - n Si interface is deduced from admittance data (low-high frequency method) and from a simulation of the response time τR(V) using Gomila's model for a non equilibrium tunnel junction. The low density of electrically active defects near mid-gap (DS < 2 × 1011 eV-1.cm-2) indicates a good passivation of dangling bonds at the dodecyl - n Si (111) interface. [ABSTRACT FROM AUTHOR]

The structural properties of nitrogenated amorphous carbon deposited by radiofrequency magnetron sputtering of graphite in pure N2 plasma are investigated as a function of the substrate temperature and radiofrequency discharge power. The film composition is derived from x-ray photoemission spectroscopy, nuclear reaction analysis and elastic recoil detection measurements and the film microstructure is discussed using infrared, Raman, x-ray photoemission and near edge x-ray absorption fine structure spectroscopic results. At low deposition temperature and low radiofrequency power, the films are soft, porous, and easily contaminated with water vapor and other atmospheric components. The concentration of nitrogen in the films is very large for low deposition temperatures (∼33.6 at. % N at 150 °C) but decreases strongly when the synthesis temperature increases (∼15 at. % N at 450 °C). With increasing deposition temperature and discharge power values, the main observed effects in amorphous carbon nitride alloys are a loss of nitrogen atoms, a smaller hydrogen and oxygen contamination related to the film densification, an increased order of the aromatic sp2 phase, and a strong change in the nitrogen distribution within the carbon matrix. Structural changes are well correlated with modifications of the optical and transport properties. [ABSTRACT FROM AUTHOR]

Stoichiometry, bonding configurations and structural properties of plasma-deposited hydrogen-rich amorphous carbon nitride a-C[sub 1-x]N[sub x]:H (0

The C and N atoms were compared to know the different local environments of these and also to understand the bonding configurations in a series of hydrogenated amorphous carbon nitrides films namely plasma enhanced chemical vapor deposition a-C (sub 1-x) N (sub x): H with 36-42 at percent hydrogen. This is done using a combination of x-ray photoemission spectroscopy (XPS), Infrared (IR), and Raman spectroscopies.