| Autor: |
Wörle, D., Grünleitner, H., Demuth, V., Kumpf, C., Strunk, H.P., Burkel, E., Schulz, M. |
| Předmět: |
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| Zdroj: |
Applied Physics A: Materials Science & Processing; 1998, Vol. 66 Issue 6, p629, 9p |
| Abstrakt: |
Abstract. Iridium silicide IrSi layers are fabricated by evaporating Ir metal on Si(100) substrates and applying a subsequent silicidation anneal at 500 Celsius. The films fabricated are structurally analyzed by X-ray diffraction and by high-resolution transmission electron microscopy. The layers are amorphous if the thickness of IrSi is less than or equal to 4 nm; they are crystalline if the thickness is > 8 nm. In between these thickness values a mixed phase occurs. The polycrystalline c-IrSi films show an increased degree of texturing with increased substrate temperature during Ir metal deposition prior to silicidation. The electro-optical properties of the films are studied by measuring the infrared optical absorption and the yield of hole photoemission across the Schottky barrier to the p-Si substrate. The Schottky barrier height of the amorphous a-IrSi to the valence band of Si is 0.17-0.18 eV. The barrier height of the polycrystalline c-IrSi depends on the degree of texturing of the silicide; the Schottky barrier height increases from 0.14 eV to 0.18 eV when the substrate temperature is increased from room temperature to 400 Celsius during the Ir metal deposition prior to the 500 Celsius silicidation. The non-linearity of the photoemission yield observed for the amorphous a-IrSi in the Fowler plot is due to an energy-dependent photon absorption of these amorphous films. An evaluation of the scattering events in the metal films shows that the mean free path for inelastic scattering is lambda[sub in] = 500 nm in the amorphous a-IrSi which is one order of magnitude larger than that in the crystalline c-IrSi. The mean free path for quasi-elastic scattering lambda[sub qe] = 0.3 nm, of the amorphous a-IrSi is in the order of the interatomic distance, indicating a localization of the electronic states. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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