Silicon L2,3 core absorption obtained at the buried Al/Si(111) interface (original) (raw)
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A High Schottky-Barrier of 1.1 eV Between Al and S-Passivated p-Type Si(100) Surface
IEEE Electron Device Letters, 2007
We report a high Schottky-barrier between Al and S-passivated p-type Si(100) surface. Capacitance-voltage measurements indicate a barrier height of 1.1 eV, while activationenergy measurements suggest 0.94-0.97 eV. Possible reasons for the discrepancy are proposed. The barrier height of 1.1 eV suggests degenerate inversion on the p-type Si surface, and Fermi statistics is used to describe its electrostatics. Although fabricated like a Schottky diode, this Al/S-passivated p-type Si(100) device works like a p-n junction diode. Temperature-dependent current-voltage measurements reveal that S passivation reduces the reverse saturation current of Al/p-type Si(100) diodes by over six orders of magnitude.
Theory of the electronic structure of the Si-SiO 2 interface
Physical Review B - PHYS REV B, 1980
A theory of the Si-SiO, interface based on recent experimental findings for silicon surfaces and their oxidation is presented. It is proposed that a simple local-orbital picture can simultaneously describe silicon, its oxidation, and the Si-SiO, interface and that two dimensionality is not essential to physically meaningful calculations of interface local densities of states. Calculations are performed which show that interface states do not arise simply from the presence of a boundary. It is argued that band tailing at the interface, like that in amorphous silicon, is due primarily to strain rather than to charged centers, and that dangling bonds at the interface should give rise to an inhomogeneously broadened discrete level at midgap.
Physical review. B, Condensed matter, 1990
We have studied the electrical properties of both orientations of the NiSi, /Si{111)interface in relation to the atomic structure at the very interface. The flat-band Schottky-barrier heights corresponding to the Aand B-type oriented silicides are shown to be 0.65 and 0.81 eV, respectively, in agreement with the literature. Measurements using medium-energy ion scattering show that the concentrations of atoms displaced from lattice sites at the Aand B-type oriented NiSi2/Si{111) interfaces are smaller than-1 X 10" Si atoms cm and-3 X 10" Si atoms cm-, respectively, ruling out the possibility that the difference in Schottky-barrier height is caused by defects. The difference should therefore be intrinsically related to the interfacial atomic geometry.
Tunneling through thin oxide interface layers in a-Si:H Schottky diodes
Journal of Applied Physics, 1992
A detailed study of hydrogenated amorphous silicon (a-Si:H) surfaces before and after thermal and plasma oxidation treatments was carried out using x-ray photoelectron spectroscopy. The thickness of the surface oxides is correlated with the electrical properties of corresponding MO Schottky barrier structures. Oxide layers up to 1.5 nm in thickness cause a decrease of the reverse current of nearly two orders in magnitude, while the forward current is hardly affected. For oxide thicknesses above 2.0 nm a large reduction in the forward current is observed. Surprisingly, the associated tunneling probabilities of the oxide interface layers in the a-Si:H Schottky diodes are the same as those previously reported for c-Si-based tunnel diodes. Tunneling in the a-Si:H devices cannot be simply described by the properties of a rectangular barrier, which is adopted most frequently in these studies. A potential form where the barrier height increases quadratically with thickness fits the observed tunneling characteristics more quantitatively, both in absolute magnitude and oxide-thickness dependence of the tunnel current.
Interface structure and Schottky barriers at epitaxial Si(111)/Pb interfaces
Surface Science Letters, 1991
Two different epitaxial Si(Ill)/Pb interfaces can be prepared. i.e. a metastable interface with a (7 x 7) and a stable interface with an incommensurate but close to (& X fi)R30° surface unit cell. Schottky barrier heights of diodes made by depositing thick Ph layers on these interfaces are very dependent on the structure at the interface (0.70 and 0.93 eV for the (7 x 7) and (6 x fi)R30° type interfaces respectively). In particular the second value is very exceptional for metal-silicon contacts. Even higher values were found from shifts in photoelectron spectra of Si covered with one ML (0.94 and 1.04 eV respectively). Evidence from ARUPS data indicates that the corresponding pinning level is associated with a discrete interface state in a common gap of Ph and Si.
The barrier height inhomogeneity in Al/p-Si Schottky barrier diodes with native insulator layer
Applied Surface Science, 2006
The current-voltage (I-V) characteristics of Al/p-Si Schottky barrier diodes (SBDs) with native insulator layer were measured in the temperature range of 150-375 K. The estimated zero-bias barrier height F B0 and the ideality factor n assuming thermionic emission (TE) theory show strong temperature dependence. Evaluation of the forward I-V data reveals an increase of zero-bias barrier height F B0 but decrease of ideality factor n with increase in temperature. The conventional Richardson plot exhibits non-linearity below 250 K with the linear portion corresponding to activation energy of 0.41 eV and Richardson constant (A *) value of 1.3 Â 10 À4 A cm À2 K À2 is determined from intercept at the ordinate of this experimental plot, which is much lower than the known value of 32 A cm 2 K 2 for holes in p-type Si. Such behavior is attributed to Schottky barrier inhomogene ties by assuming a Gaussian distribution of barrier heights (BHs) due to barrier height inhomogeneities that prevail at interface. Also, F B0 versus q/2kT plot was drawn to obtain evidence of a Gaussian distribution of the BHs, and values of F B0 = 1.055 eV and s 0 = 0.13 V for the mean BH and zero-bias standard deviation have been obtained from this plot, respectively. Thus, the modified ln ðI 0 =T 2 Þ À q 2 s 2 o =2k 2 T 2 versus q/kT plot gives F B0 and A * as 1.050 eV and 40.08 A cm À2 K À2 , respectively, without using the temperature coefficient of the barrier height. This value of the Richardson constant 40.03 A cm À2 K À2 is very close to the theoretical value of 32 A K À2 cm À2 for p-type Si. Hence, it has been concluded that the temperature dependence of the forward I-V characteristics of the Al/p-Si Schottky barrier diodes with native insulator layer can be successfully explained on the basis of TE mechanism with a Gaussian distribution of the barrier heights.
Electronic states and microstructure at the silicide-silicon interface
Thin Solid Films, 1982
The understanding of Schottky barrier formation at the silicide-silicon contact requires information on the electronic states and microstructure of the reacted interface. Considerable progress has been made recently in the study of these interface properties using surface spectroscopy, transmission electron microscopy and ion channeling techniques. This review is focused mainly on the results for the near-noble metal" silicides with some brief discussions for the refractory metal silicides. The basic bonding characteristics in silicides are discussed first with emphasis on the role of hybrid states between metal d and Sip orbitals. Then the stoichiometry and microstructure of the interface as well as their effect on the electronic properties are described. Spectroscopy evidence is given to show the existence of interface states in the vicinity of the band gap. Finally, measurements of Schottky barrier height are discussed in an attempt to assess the effects of phase stoichiometry and microstructure on the electrical properties of the Schottky barrier.
Journal of Applied Physics, 2010
The forward bias current-voltage ͑I-V͒ characteristics of Au/n-Si Schottky barrier diodes ͑SBDs͒ with Zn doped poly͑vinyl alcohol͒ ͑PVA:Zn͒ interfacial layer have been investigated in the wide temperature range of 80-400 K. The conventional Richardson plot of the ln͑I o / T 2 ͒ versus q / kT has two linear regions: the first region ͑200-400 K͒ and the second region ͑80-170 K͒. The values of activation energy ͑E a ͒ and Richardson constant ͑A ء ͒ were obtained from this plot and especially the values of A ء are much lower than the known theoretical value for n-type Si. Also the value of E a is almost equal to the half of the band gap energy of Si. Therefore, the ⌽ ap versus q / 2kT plot was drawn to obtain the evidence of a Gaussian distribution ͑GD͒ of barrier heights ͑BHs͒ and it shows two linear region similar to ln͑I o ͒ / T 2 versus q / kT plot. The analysis of I-V data based on thermionic emission of the Au/PVA:Zn/n-Si SBDs has revealed the existence of double GD with mean BH values ͑⌽ B0 ͒ of 1.06 eV and 0.86 eV with standard deviation ͑͒ of 0.110 eV and 0.087 V, respectively. Thus, we modified ln͑I o / T 2 ͒ − ͑q͒ 2 / 2͑kT͒ 2 versus q / kT plot for two temperature regions ͑200-400 K and 80-170 K͒ and it gives renewed mean BHs ⌽ B0 values as 1.06 eV and 0.85 eV with Richardson constant ͑A ء ͒ values 121 A / cm 2 K 2 and 80.4 A / cm 2 K 2 , respectively. This obtained value of A ء = 121 A / cm 2 K 2 is very close to the known theoretical value of 120 A / cm 2 K 2 for n-type Si.
Schottky barrier formation at Pd, Pt, and Ni/Si(111) interfaces
Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 1983
Synchrotron radiation photoemission measurements have been used to study Schottky barrier formation and the electronic structure of interfaces of Si with Pt, Pd, and Ni. High resolution photoemission spectroscopy of the Si 2p core levels has been used to monitor changes in band bending (or Schottky barrier height) when the metal is deposited on the Si surface. Barrier height measurements on sputter-cleaned (i.e., ion bombardment and subsequent annealing) and on heat-cleaned (i.e., annealing only) samples show no effect of the ion bombardment on the rate of change in barrier height with coverage. The Schottky barrier height reaches a saturation value within 1 Å metal coverage for Pt and Ni, but it requires ∼4.5 Å for Pd. For the Ni/Si interface, measurements of the valence electronic structure indicate that the Schottky barrier height is unrelated to the existence of a metallic character of the contact.