Articles you may be interested inAb initio quantum transport simulation of silicide-silicon contacts J. Appl. Phys. 111, 014305 (2012); 10.1063/1.3674277 Deposition and 1.54 μm Er 3+ luminescent properties of erbium-doped hydrogenated amorphous silicon thin films by electron cyclotron resonance plasma enhanced chemical vapor deposition of SiH 4 with concurrent sputtering of erbium

In this article, we report on the characterization of a photovoltaic detector based on an n-type GaN Schottky barrier. We first present the photovoltaic responsivity above the gap. Its spectrum is explained by the combined effects of absorption and diffusion. The hole diffusion length is estimated to be in the 0.1 μm range with a numerical model. The photoresponse below the gap is also investigated and it is shown that the current generated by the internal photoemission is the major contribution to the photocurrent at reverse biases at 80 K. At room temperature, an additional component to the photocurrent is clearly demonstrated and identified. This extra current stems from the existence of traps. Several spectroscopy techniques are used to characterize those traps. The supplementary current emitted from the traps in the depletion region accounts for the spectral and the temporal behavior of the Schottky photodetector at room temperature.

Using the temperature dependence of Schottky-barrier heights in epitaxial silicide-silicon diodes, we show that the metal Fermi level at the interface is pinned either relative to the Si conduction band or to the Si valence band. The contribution of the semiconductor to the interface states is restricted to the semiconductor band nearest in energy. We then discuss the effect of the metal on the interface states and propose different models of Schottky-barrier formation that may account for these results.Despite decades of intense study on metalsemiconductor contacts, the enigma of Schottky-barrier formation still challenges basic solid-state research. The first explanation, given by Schottky, ' was simply based on the difference of the work function between the metal and the semiconductor. This model did not account for the low dependence of Schottky-barrier heights (SBH) on metal work function and the deviations were explained by Bardeen in terms of semiconductor interface states. In this approach, the Fermi level is pinned in the semiconductor band gap by electronic states, so that the SBH is equal to the energetic depth of the pinning states below the conduction band. The origin and the nature of these states still remain enigmatic; the theoretical attempts are often questionable because of a crucial lack of experimental evidence. Some authors have argued that the SBH is nearly independent of the metal and it has been currently advanced that the pinning states are associated with the semiconductor (SC) alone and are related to metal-induced gap states, ' native or antisite defects at or near the SC surface. On the other hand, various correlations have been made with heats of formation, polarizability, ionicity, and even the anion work function in III-V compounds with intent to propose again an effective work-function model. The diversity of models and invoked assumptions, which can be easily explained by the lack of precise data on SBH, imply that the most basic aspects of Schottky-barrier formation have not yet been established.In this paper, we therefore present new and original data which are relevant for the understanding of the Fermi energy pinning in Schottky diodes. Our results throw new light on the formation mechanisms of the Schottky barrier (SB) and show that, in a metal-semiconductor contact, the Ez pinning is possible to either the valence band or the conduction band of the semiconductor. In our study, we used silicide-silicon heterostructures which appear to be ideal candidates for investigating the SB formation for two reasons: from a metallurgical point of view, the silicide layer is epitaxial on Si, so the interface is free of interfacial layer, and the contact is really intimate; from an electrical point of view, the SBH measurements are highly reproducible and the great variety of sil-icides allows the SBH values to scan the entire Si band gap. ' Among these silicides, special attention is devoted to ErSi2 and CoSi2 because of their opposite behavior when deposited on Si: while the former le...

We have studied the fabrication of Pt/Au Schottky diodes on n-type GaN. We show that the electrical characteristics of the diodes are strongly dependent on the surface chemical treatment before the metal deposition. Lowest leakage currents were obtained by the use of a HC1 solution. We also show that annealing the diode at a moderate temperature (400°C) leads to reduced reverse currents. In order to explain these results, we measured the density of deep levels in the Schottky diode depletion region before and after the annealing process. We did not observe any significant difference in the bulk density of defects due to the anneal. We also studied the temperature dependence of the reverse currents and found a low activation energy. Our results are interpreted in terms of electrical defects at the metal-GaN surface.

Electrical measurements (resistivity, Hall effect, and superconducting critical temperature) are performed in epitaxial CoSi2 layers obtained by room-temperature codeposition of Co and Si on 〈111〉 Si subsequently annealed between 250 and 650 °C. On the one hand, the CoSi2 layers annealed at low temperature (250–350 °C) exhibit poorer electrical characteristics than the films realized by solid phase epitaxy at 650 °C, because of both a lack of carriers and a degraded mobility. A possible origin of this fact could be the presence of unreacted Co atoms in the metal layer. On the other hand, the films annealed ex situ at 700 °C show excellent electrical characteristics, together with mirror-like surfaces and extremely smooth Si/CoSi2 interfaces, for silicide thicknesses ranging from 35 up to 500 Å. Furthermore, by comparing the films obtained by the solid phase epitaxy and the codeposition techniques, we show that the long-range roughness (few hundreds of angstroms) has no major influence on the steep increase of resistivity with decreasing film thicknes observed in ultrathin CoSi2 layers.