Solid-Phase Epitaxy of Ti-Implanted LiNbO3

1987 ◽  
Vol 93 ◽  
Author(s):  
D. B. Poker
Keyword(s):  
Activation Energy ◽  
Optical Waveguides ◽  
Solid Phase ◽  
Complete Removal ◽  
Liquid Nitrogen Temperature ◽  
Index Of Refraction ◽  
Optical Index ◽  
Epitaxial Regrowth ◽  
Residual Damage ◽  
Water Saturated

ABSTRACTThe implantation of Ti into LiNbO3 has been studied as a means of altering the optical index of refraction to produce optical waveguides. Implanting 2 × 1017 atoms/cm2 of 360-keV Ti at liquid nitrogen temperature produces a highly damaged region extending to a depth of about 4000 Å. Solid-phase epitaxial regrowth of the LiNbO3 can be achieved by annealing in a water-saturated oxygen atmosphere at 400°C, though complete removal of the residual damage usually requires temperatures in excess of 800°C. The solid-phase epitaxial regrowth rate exhibits an activation energy of 2 eV at doses below 3 × 1016 Ti/cm2, but both the regrowth rate and activation energy decrease at higher doses. At doses above 1 × 1017 Ti/cm2, the solid-phase epitaxial regrowth occurs only at temperatures above 800°C.

Solid-phase epitaxy of Ti-implanted LiNbO3

1989 ◽  
Vol 4 (2) ◽  
pp. 412-416 ◽  
Author(s):  
D. B. Poker ◽  
D. K. Thomas
Keyword(s):  
Optical Waveguides ◽  
Solid Phase ◽  
Complete Removal ◽  
Amorphous Region ◽  
Liquid Nitrogen Temperature ◽  
High Dose ◽  
Solid Phase Epitaxy ◽  
Complete Recrystallization ◽  
Water Saturated ◽  
Saturated Oxygen

The solid-phase epitaxy of LiNbO3 following ion implantation of Ti dopant for the purpose of producing optical waveguides has been studied. Implanting 360-keV Ti at liquid nitrogen temperature produces a highly damaged region extending to a depth of about 400 nm. This essentially amorphous region can be recrystallized epitaxially by annealing in a water-saturated oxygen atmosphere at temperatures near 400 °C. though complete removal of all irradiation-induced damage requires temperatures in excess of 600 °C. The activation energy of the regrowth is 2.0 eV for implanted fluences below 3 ⊠ 1016 Ti/cm2. At higher fluences the regrowth proceeds more slowly, and Ti dopant segregates at the regrowth interface. Complete recrystallization following high-dose implantation requires annealing temperatures in excess of 800 °C.

Optical Waveguide Formation by Ion Implantation of Ti or Ag

1988 ◽  
Vol 100 ◽  
Author(s):  
D. B. Poker ◽  
D. K. Thomas
Keyword(s):  
Ion Implantation ◽  
Concentration Profile ◽  
Optical Waveguides ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Effective Means ◽  
Complete Removal ◽  
Solid Phase Epitaxy ◽  
Annealing Temperatures ◽  
Residual Damage

ABSTRACTIon implantation of Ti into LINbO3 has been shown to be an effective means of producing optical waveguides, while maintaining better control over the resulting concentration profile of the dopant than can be achieved by in-diffusion. While undoped, amorphous LiNbO3 can be regrown by solid-phase epitaxy at 400°C with a regrowth velocity of 250 Å/min, the higher concentrations of Ti required to form a waveguide (∼10%) slow the regrowth considerably, so that temperatures approaching 800°C are used. Complete removal of residual damage requires annealing temperatures of 1000°C, not significantly lower than those used with in-diffusion. Solid phase epitaxy of Agimplanted LiNbO3, however, occurs at much lower temperatures. The regrowth is completed at 400°C, and annealing of all residual damage occurs at or below 800°C. Furthermore, the regrowth rate is independent of Ag concentration up to the highest dose implanted to date, 1 × 1017 Ag/cm2. The usefulness of Ag implantation for the formation of optical waveguides is limited, however, by the higher mobility of Ag at the annealing temperature, compared to Ti.

Solid-phase epitaxy of ion-implanted LiNbO3 for optical waveguide fabrication

1987 ◽  
Vol 2 (2) ◽  
pp. 222-230 ◽  
Author(s):  
Ch. Buchal ◽  
P. R. Ashley ◽  
B. R. Appleton
Keyword(s):  
Optical Waveguides ◽  
Solid Phase ◽  
Surface Region ◽  
Liquid Nitrogen Temperature ◽  
High Concentration ◽  
Near Surface ◽  
Crystalline Substrate ◽  
A New Technique ◽  
Waveguide Fabrication ◽  
Water Saturated

A new technique for successfully fabricating high-quality optical waveguides in LiNbO3 is reported. A high concentration of Ti is implanted with the substrate at liquid nitrogen temperature and an amorphous, Ti-rich, nonequilibrium phase is produced in the implanted, near-surface region. Subsequent thermal annealing in water-saturated oxygen atmosphere at up to 1000°C initiates solid-phase epitaxial regrowth onto the crystalline substrate. A highquality single crystalline layer results that is rich in Ti and has excellent waveguiding properties.

Precision measurements of the effect of implanted boron on silicon solid phase epitaxial regrowth

1988 ◽  
Vol 3 (2) ◽  
pp. 298-308 ◽  
Author(s):  
Won Woo Park ◽  
M. F. Becker ◽  
R. M. Walser
Keyword(s):  
Activation Energy ◽  
Critical Temperature ◽  
Solid Phase ◽  
Laser Interferometry ◽  
Thermal Fluctuations ◽  
Solubility Limit ◽  
Activation Entropy ◽  
Epitaxial Regrowth ◽  
Sample Technique ◽  
Differential Increase

The epitaxial recrystallization rates of self-ion amorphitized layers in silicon wafers with 〈100〉 substrate orientation were measured by in situ, high precision, isothermal cw laser interferometry. With this one-sample technique the changes produced by implanted boron impurity concentrations (NB) in the activation energy Ea and preexponential V0 of solid phase epitaxy were measured for concentrations in the range 5 × 1018 cm−3 < NB < 3 × 1020 cm−3 and for temperatures from 450 to 550°C. The differential changes in Ea produced were measured to within ± 23 meV when systematic errors were eliminated. Changes in activation energy and entropy [Ea and log (V0)] were found to be linearly correlated for all concentrations. This observation is consistent with the idea that electronically active impurities alter regrowth velocities by reducing the critical temperature for disordering at some of the interfacial sites at which elementary reconstructive processes are driven by thermal fluctuations. For small Nn, the critical temperature of the impurity-modified reconstruction is estimated at 1200K, approximately 200 K below the melting temperature of amorphous silicon. The Ea decreased exponentially with NB to a concentration Ninfl, larger than the estimated equilibrium solubility limit, where there was an inflection point in the V vs NB curve. The Ea increased for values of NB larger than Ninfl, showing that the differential increase in V for higher concentrations was due to a differential increase in the activation entropy. A change in the correlation between Ea and log (V0) at Ninfl indicated that larger NB produced an additional reduction of the critical temperature of the reconstruction. For small NB, the data support a simple Fermi level shifting model for the “electronic effect” of impurities on SPE (solid phase epitaxial) regrowth.

Supersaturated Substitutional Solid Solution after Solid Phase Epitaxial Regrowth by Incoherent Light Scanning.

1981 ◽  
Vol 4 ◽  
Author(s):  
L. Pedulli ◽  
L. Correra
Keyword(s):  
Solid Phase ◽  
Substitutional Solid Solution ◽  
Dislocation Loops ◽  
Incoherent Light ◽  
Dopant Activation ◽  
Epitaxial Regrowth ◽  
Electron Microscopy Analysis ◽  
Residual Damage ◽  
Microscopy Analysis ◽  
Minority Carriers

ABSTRACTSupersaturated substitutional solid solutions of 2×101531P+ /cm2 implanted at 10 keV in (100) Silicon were obtained after solid phase epitaxial regrowth using a scanning beam of incoherent light. The main results are: a) the maximum P+ concentration exceeds of about 5 times the maximum solid solubility at the temperature reached by the sample; b) the carrier concentration profile shows a complete dopant activation without diffusion of the implanted ions; c) an improvement of minority carriers diffusion length in the bulk is often observed; d) the values of carrier mobilities are similar to those obtained after liquid phase regrowth by pulsed ruby laser; e) a very good recovery of the damage is obtained: Rutherford backscattering spectra show that the dechanneling fraction is very close to the value of virgin samples and Trasmission Electron Microscopy analysis shows that the residual damage consists of dislocation loops of about 30 Å diameter confined in a region at about 500 Å depth.

In Situ Tem Studies of The Growth of Strained Si1-xGex By Solid Phase Epitaxy

1990 ◽  
Vol 202 ◽  
Author(s):  
D. C. Paine ◽  
D. J. Howard ◽  
N. D. Evans ◽  
D. W. Greve ◽  
M. Racanelli ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Surface Region ◽  
In Situ Tem ◽  
Solid Phase Epitaxy ◽  
Near Surface ◽  
Strained Layer ◽  
Epitaxial Regrowth

ABSTRACTIn this paper we report on the epitaxial growth of strained thin film Si1-xGex on Si by solid phase epitaxy. For these solid phase epitaxy experiments, a 180-nm-thick strained-layer of Si1-xGex with xGe=11.6 at. % was epitaxially grown on <001> Si using chemical vapor deposition. The near surface region of the substrate, including the entire Si1-xGex film, was then amorphized to a depth of 380 nm using a two step process of 100 keV, followed by 200 keV, 29Si ion implantation. The epitaxial regrowth of the alloy was studied with in situ TEM heating techniques which enabled an evaluation of the activation energy for strained solid phase epitaxial regrowth. We report that the activation energy for Si1-xGex (x=l 1.6 at. %) strained-layer regrowth is 3.2 eV while that for unstrained regrowth of pure Si is 2.68 eV and that regrowth in the alloy is slower than in pure Si over the temperature range 490 to 600°C.

(A)thermal migration of Ge during junction formation in s-Si layers grown on thin SiGebuffer layers

2004 ◽  
Vol 809 ◽  
Author(s):  
W. Vandervorst ◽  
B.J. Pawlak ◽  
T. Janssens ◽  
B. Brijs ◽  
R. Delhougne ◽  
...  
Keyword(s):  
Activation Energy ◽  
Distribution Function ◽  
Solid Phase ◽  
Silicon Layer ◽  
Damage Distribution ◽  
Strained Si ◽  
Advanced Technologies ◽  
Epitaxial Regrowth ◽  
Junction Formation ◽  
Determining Factor

ABSTRACTSolid phase epitaxial regrowth (SPER) has been proven to be highly advantageous for ultra shallow junction formation in advanced technologies. Application of SPER to strained Si/SiGe structures raises the concern that the Ge may out diffuse during the implantation and/or anneal steps and thus reduce the strain in the top silicon layer.In the present studies we expose 8-30 nm strained silicon layers grown on thin relaxed SiGe-buffers, to implant conditions and anneal cycles, characteristic for formation of the junctions by solid phase epitaxial regrowth and conventional spike activation. The resulting Geredistribution is measured using SIMS. Based on the outdiffused Ge-profiles the Ge-diffusion coefficient has been determined in the temperature range of 800-1100C from which an activation energy of ∼ 3.6 eV can be deduced. Up to 1050 C, 10 min, even a 30 nm strained film remains highly stable and shows only very moderate outdiffusion.We also have observed a far more efficient, athermal Ge-redistribution process linked to the implantation step itself. This was studied by analysing the Ge-redistribution following an Asimplant (2-15 keV, 5 1014 – 3 1015 at/cm2). It is shown that the energy of the implant species (or more specifically the position of the damage distribution function relative to the Ge-edge) plays a determining factor with respect to the Ge-migration. For implants whereby the damage distribution overlaps with the Ge-edge, a very efficient transport of the Ge is observed, even prior to any anneal cycle. The migration is entirely correlated with the collision cascade and the resulting (forward!) Ge-recoil distribution. The scaling with dose for a given energy links the observed Ge-profile with a broadening mechanism related to the number of atom displacements induced in the sample within the vicinity of the Si-SiGe-transition.

Ion Implantation of Ti INTO LiNbO3: Fabrication of Waveguides and Simple Modulators

1989 ◽  
Vol 152 ◽  
Author(s):  
C. W. White ◽  
D. K. Thomas ◽  
P. R. Ashley ◽  
W. S. C. Chang ◽  
C. Buchal
Keyword(s):  
Ion Implantation ◽  
Solid Phase ◽  
Surface Region ◽  
Amorphous Region ◽  
Index Of Refraction ◽  
Near Surface ◽  
Channel Waveguides ◽  
High Doses ◽  
Water Saturated ◽  
Saturated Oxygen

ABSTRACTIon implantation has been used to introduce Ti at very high doses (>3 × 1017 /cm2) into the near-surface region of LiNbO3 to change the index of refraction.’ In the as-implanted state, the near surface is amorphous. Thermal annealing in water-saturated oxygen 1000°C crystallizes the amorphous region and incorporates the Ti into substitutional sites in the lattice at concentrations that exceed 10 at.%. Recrystallization takes place by solid-phase epitaxy. Both planar and channel waveguides have been fabricated with optical attenuations of <1 dB/cm. Both Mach-Zehnder and Bragg modulators have been fabricated using Ti implantation of LiNbO3. The characteristics of these devices have been determined and will be reported. The higher Ti concentrations which can be achieved by implantation allows tighter mode confinement and smaller mode profiles than with Ti-diffused guides.

Interferometric (Fourier-Spectroscopic) Measurement of Electron Energy Distributions

1990 ◽  
Vol 48 (2) ◽  
pp. 110-111 ◽  
Author(s):  
F. Hasselbach ◽  
A. Schäfer
Keyword(s):  
Group Velocity ◽  
Wave Packets ◽  
Index Of Refraction ◽  
Electron Wave ◽  
Fringe Contrast ◽  
Faraday Cage ◽  
Optical Index ◽  
Wien Filter ◽  
Coherent Wave ◽  
Electric And Magnetic Fields

Möllenstedt and Wohland proposed in 1980 two methods for measuring the coherence lengths of electron wave packets interferometrically by observing interference fringe contrast in dependence on the longitudinal shift of the wave packets. In both cases an electron beam is split by an electron optical biprism into two coherent wave packets, and subsequently both packets travel part of their way to the interference plane in regions of different electric potential, either in a Faraday cage (Fig. 1a) or in a Wien filter (crossed electric and magnetic fields, Fig. 1b). In the Faraday cage the phase and group velocity of the upper beam (Fig.1a) is retarded or accelerated according to the cage potential. In the Wien filter the group velocity of both beams varies with its excitation while the phase velocity remains unchanged. The phase of the electron wave is not affected at all in the compensated state of the Wien filter since the electron optical index of refraction in this state equals 1 inside and outside of the Wien filter.

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

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