A melting model for pulsing‐laser annealing of implanted semiconductors
01 Feb 1979-Journal of Applied Physics (American Institute of PhysicsAIP)-Vol. 50, Iss: 2, pp 788-797
TL;DR: In this paper, the transition to single crystal of ion-implanted amorphous Si and Ge layers is described in terms of a liquid phase epitaxy occurring during pulsing-laser irradiation.
Abstract: The transition to single crystal of ion‐implanted amorphous Si and Ge layers is described in terms of a liquid‐phase epitaxy occurring during pulsing‐laser irradiation. A standard heat equations including laser light absorption was solved numerically to give the time evolution of temperature and melting as a function of the pulse energy density and its duration. The structure dependence of the absorption coefficient and the temperature dependence of the thermal conductivity were accounted for in the calculations. In this model the transition to single crystal occurs above a well‐defined threshold energy density at which the liquid layer wets the underlying single‐crystal substrate. Experiments were performed in ion‐implanted amorphous layers of thicknesses ranging between 500 and 9000 A. The energy densities of the Q‐switched ruby laser ranged between 0.2 and 3.5 J/cm2; time durations of 20 and 50 ns were used. The experimental data are in good agreement with the calculated values for the amorphous thickness–energy−density threshold. The model deals mainly with plausibility arguments and does not account for processes occuring in the near‐threshold region or below the melting temperature.
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TL;DR: In this article, the formation of supersaturated substitutional alloys by ion implantation and rapid liquid phase-epitaxial regrowth induced by pulsed laser annealing has been studied using Rutherford backscattering, ion channeling analysis.
Abstract: The formation of supersaturated substitutional alloys by ion implantation and rapid liquid‐phase‐epitaxial regrowth induced by pulsed laser annealing has been studied using Rutherford backscattering, ion channeling analysis. Group‐III (Ga, In) and group‐V (As, Sb, Bi) dopants have been implanted into single‐crystal silicon at doses ranging from 1×1015 to 1×1017/cm2. The samples were annealed with a Q‐switched ruby laser (energy density ∼1.5 J/cm2, pulse duration ∼15×10−9 sec). Ion channeling analysis shows that laser annealing incorporates these dopants into substitutional lattice sites at concentrations far in excess of the equilibrium solid solubility. Channeling measurements indicate the silicon crystal is essentially defect free after laser annealing. Also values for the maximum dopant concentration (Cmaxs) that can be incorporated into substitutional lattice sites are determined for our annealing conditions. Dopant profiles determined by Rutherford backscattering are compared to model calculations wh...
311 citations
TL;DR: In this article, the impact of composition, orientation, and microstructure on the piezoelectric properties of perovskite thin films such as PbZr1−xTixO3 (PZT) is reviewed.
Abstract: Piezoelectric microelectromechanical systems (MEMS) offer the opportunity for high-sensitivity sensors and large displacement, low-voltage actuators. In particular, recent advances in the deposition of perovskite thin films point to a generation of MEMS devices capable of large displacements at complementary metal oxide semiconductor-compatible voltage levels. Moreover, if the devices are mounted in mechanically noisy environments, they also can be used for energy harvesting. Key to all of these applications is the ability to obtain high piezoelectric coefficients and retain these coefficients throughout the microfabrication process. This article will review the impact of composition, orientation, and microstructure on the piezoelectric properties of perovskite thin films such as PbZr1−xTixO3 (PZT). Superior piezoelectric coefficients (e31, f of −18 C/m2) are achieved in {001}-oriented PbZr0.52Ti0.48O3 films with improved compositional homogeneity on Si substrates. The advent of such high piezoelectric responses in films opens up a wide variety of possible applications. A few examples of these, including low-voltage radio frequency MEMS switches and resonators, actuators for millimeter-scale robotics, droplet ejectors, energy scavengers for unattended sensors, and medical imaging transducers, will be discussed.
282 citations
TL;DR: In this paper, the authors investigated the mechanisms controlling the nanostructuring of thin metal-on-oxide films by nanosecond pulsed excimer lasers and found that the resulting nanoparticle size distribution is influenced by the surface roughness of the initial film and the Rayleigh instability criterion.
Abstract: he mechanisms controlling the nanostructuring of thin metal-on-oxide films by nanosecond pulsed excimer lasers are investigated. When permitted by the interfacial energetics, the breakup of the metal film into nanoscale islands is observed. A range of metals (Au, Ag, Mo, Ni, Ti, and Zn) with differing physical and thermodynamic properties, and differing tendencies for oxide formation, are investigated. The nature of the interfacial metal-substrate interaction, the thermal conductivity of the substrate, and the initial thickness of the metal film are all shown to be of importance when discussing the mechanism for nanoscale island formation under high fluence irradiation. It is postulated that the resulting nanoparticle size distribution is influenced by the surface roughness of the initial film and the Rayleigh instability criterion. The results obtained are compared with simulations of the heat transfer through the film in order to further elucidate the mechanisms. The results are expected to be applicable to the laser induced melting of a large range of different materials, where poor wetting of substrate by the liquid phase is observed.
243 citations
IBM1
TL;DR: In this paper, the importance of the electron-hole plasma produced by the laser to the annealing process was discussed and it was shown that the process does not involve normal thermal melting and recrystallization.
216 citations
TL;DR: In this paper, the authors studied the invariance properties of the nonlinear diffusion equation (∂/∂x) and showed that an infinite number of one-parameter Lie-Backlund groups are admitted if and only if the conductivity C (u) =a (u+b)−2
Abstract: We study the invariance properties (in the sense of Lie–Backlund groups) of the nonlinear diffusion equation (∂/∂x)[C (u)(∂u/∂x)]−(∂u/∂t) =0 We show that an infinite number of one‐parameter Lie–Backlund groups are admitted if and only if the conductivity C (u) =a (u+b)−2 In this special case a one‐to‐one transformation maps such an equation into the linear diffusion equation with constant conductivity, (∂2ū/∂x2)−(∂ū/∂t) =0 We show some interesting properties of this mapping for the solution of boundary value problems
208 citations
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TL;DR: In this article, the real and imaginary parts of the dielectric constant and the function describing the energy loss of fast electrons traversing the materials are deduced from the Kramers-Kronig relations.
Abstract: Reflectance data are presented for Si, Ge, GaP, GaAs, InAs, and InSb in the range of photon energies between 1.5 and 25 eV. The real and imaginary parts of the dielectric constant and the function describing the energy loss of fast electrons traversing the materials are deduced from the Kramers-Kronig relations. The results can be described in terms of interband transitions and plasma oscillations. A theory based on the frequency-dependent dielectric constant in the random phase approximation is presented and used to analyze these data above 12 eV, where the oscillator strengths coupling the valence and conduction bands are practically exhausted. The theory predicts and the experiments confirm essentially free electron-like behavior before the onset of $d$-band excitations and a plasma frequency modified from that of free electrons due to oscillator strength coupling between valence and $d$ bands and $d$-band screening effects. These complications are absent in Si. The energy loss functions obtained from optical and characteristic energy loss experiments are also found to be in good agreement. Arguments for interpreting structure in the reflectance curves above 16 eV in terms of $d$-band excitations are given.
1,749 citations
01 Dec 1973
TL;DR: In this paper, the authors review some of the general features of the characteristics of implanted layers in terms of depth distribution, radiation damage, and electron activity in compound semiconductors, particularly GaAs.
Abstract: Ion implantation is being applied extensively to silicon device technology. Two principle features are utilized- 1) charge control in MOS structures for threshold shift, autoregistration, and complementary wells and 2) distribution control in microwave and bipolar structures. Another feature that has not been extensively exploited is to combine the advantages of the high resolution capabilities of electric beam pattern delineation with the low lateral spread inherent in the implantation process. This talk reviews some of the general features of the characteristics of implanted layers in terms of depth distribution, radiation damage and electron activity. Implantation processes in silicon are reasonably well understood. There remain areas which require further clarification. For compound semiconductors, particularly GaAs, implantation techniques offer attractive possibilities for the fabrication of high frequency devices. In these materials, the substrate temperature during implantation and the dielectric coating required to prevent dissociation during thermal anneal play major roles.
1,221 citations
01 Jan 1983
TL;DR: In this paper, the authors review some of the general features of the characteristics of implanted layers in terms of depth distribution, radiation damage, and electron activity in compound semiconductors, particularly GaAs.
Abstract: Ion implantation is being applied extensively to silicon device technology. Two principle features are utilized- 1) charge control in MOS structures for threshold shift, autoregistration, and complementary wells and 2) distribution control in microwave and bipolar structures. Another feature that has not been extensively exploited is to combine the advantages of the high resolution capabilities of electric beam pattern delineation with the low lateral spread inherent in the implantation process. This talk reviews some of the general features of the characteristics of implanted layers in terms of depth distribution, radiation damage and electron activity. Implantation processes in silicon are reasonably well understood. There remain areas which require further clarification. For compound semiconductors, particularly GaAs, implantation techniques offer attractive possibilities for the fabrication of high frequency devices. In these materials, the substrate temperature during implantation and the dielectric coating required to prevent dissociation during thermal anneal play major roles.
1,188 citations
422 citations