A detailed analysis of the formation of Pt 2 Si and PtSi silicides is proposed, based on x-ray photoelectron spectroscopy ͑XPS͒, transmission electron microscopy ͑TEM͒, and electrical characterizations. Published kinetics of the Pt 2 Si and PtSi transformations under ultrahigh vacuum condition are consolidated on the basis of XPS measurements performed during an in situ annealing at a constant heating rate. At room temperature, an incomplete Pt x Si reaction is clearly identified by XPS depth profiling. Using rapid thermal annealing at 300, 400, and 500 °C, the sequential Pt-Pt 2 Si-PtSi reaction chain is found to be completed within 2 min. Outdiffusion of silicon to the top surface is shown to be responsible for the formation of a thin SiO 2 capping layer at 500 °C. Pileup of oxygen occurring at the Pt 2 Si/Pt reaction front is clearly identified as an inhibiting factor of the silicidation mechanism. Another incomplete reaction scheme limited to the unique formation of Pt 2 Si is exemplified in the case of ultra thin silicon-on-insulator films. Finally, current drive measurements on PtSi Schottky contacts have allowed us to identify 300 °C as the optimum annealing temperature while TEM cross sections demonstrate the formation of a smooth and continuous PtSi/Si interface at 300 °C.
In this paper, we present a systematic study of the effect of growth parameters on the structural and optical properties of InAs quantum dot ͑QD͒ grown under Stranski-Krastanov mode by molecular beam epitaxy. The dot density is significantly reduced from 1.9ϫ10 10 to 0.6ϫ10 10 cm Ϫ2 as the growth rate decreases from 0.075 to 0.019 ML/s, while the island size becomes larger. Correspondingly, the emission wavelength shifts to the longer side. By increasing the indium fraction in the InGaAs capping layer, the emission wavelength increases further. At indium fraction of 0.3, a ground state transition wavelength as long as 1.4 m with the excited state transition wavelength of around 1.3 m has been achieved in our dots. The optical properties of QDs with a ground state transition wavelength of 1.3 m but with different growth techniques were compared. The QDs grown with higher rate and embedded by InGaAs have a higher intensity saturation level from excitation dependent photoluminescence measurements and a smaller intensity decrease from temperature dependent measurements. Finally, single mirror light emitting diodes with a QD embedded in InGaAs have been fabricated. The quantum efficiency at room temperature is 1.3%, corresponding to a radiative efficiency of 21.5%.
In this paper, the reverse current characteristics of Si p-n junction diodes are analyzed in detail, in order to obtain an improved analysis of the underlying material parameters (generation and recombination lifetime, thermal activation energy). For that purpose, measurements on different geometry diodes are combined in order to separate peripheral from volume components. Using the correct depletion capacitance of the p-n junction, one can separate the diffusion from the generation component. From a study of the behavior with changing temperature, it is concluded that the peripheral generation component is due to surface generation by interface states. This is further supported by measurements on gated diodes, wh:Lch yield an extra feature that is speculated to be related to the surface generation along the isolation oxide edges. For the volume generation component, widely different activation energies have been found, depending on whether an internal gettering step was applied or not. A good agreement with deep-level parameters and trap profiles obtained by deep level transient spectroscopy has been found. In the case of Czochralski material, there exists a clear correlation with the oxygen-precipitation related extended defects. Finally, it is reported that the electric field dependence of the generation current component is stronger than expected from the Poole-Frenkel effect only, with an activation energy lowering which is much greater. Trap-assisted tunneling is a possible explanation.
An accurate method for the extraction of the reverse diffusion current component in a silicon p-n junction diode is proposed. It combines capacitance–voltage and current–voltage measurements on an array of diodes with different geometry in order to separate the peripheral and the volume leakage current components. The corrected volume capacitance is then used to calculate the depletion width as a function of the reverse bias. Extrapolation of the reverse current to zero depletion width results in the diffusion current part, both for the volume and for the peripheral component. From the temperature dependence, a thermal activation energy of 1.12 eV is obtained. The volume diffusion current density of the p-type Czochralski wafers studied, shows a pronounced substrate dependence, while the peripheral diffusion current density is constant. Finally, the implications for the extraction of the effective bulk recombination lifetime are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.