Er Implantation Research Articles

Redistribution of erbium during the crystallization of buried amorphous silicon layers

The redistribution of Er during its implantation in silicon at doses close to the amorphization threshold and its subsequent solid-phase epitaxial (SPE) crystallization is investigated. The formation of a buried amorphous (a) layer is discovered at Er doses equal to 5×1013 and 1×1014 cm−2 using Rutherford backscattering. The segregation of Er in this case takes place inwardly from the two directions corresponding to the upper and lower boundaries of the buried αlayer and leads to the formation of a concentration peak at the meeting place of the two crystallization fronts. A method for calculating the coordinate dependence of the segregation coefficient k from the distribution profiles of the erbium impurity before and after annealing is proposed. The k(x) curve exhibits a drop, whose width increases with decreasing Er implantation dose. Its appearance is attributed to the nonequilibrium nature of the segregation process at the beginning of SPE crystallization.

Structural and photoluminescence studies of Er implanted Be doped and undoped low-temperature grown GaAs

Characteristic 1.54 μm Er3+ emission has been observed from Er-implanted and annealed, low-temperature grown GaAs Be doped and undoped samples. Er plateau implantations (480, 155, and 40 keV successive implants) were performed at 300 °C covering calculated Er concentrations from 1018 up to 1020 Er/cm3. Cross-sectional transmission electron microscopy studies reveal very little structural damage for these elevated temperature implants up to an Er total fluence of 1.36×1014 Er/cm2. No Er emission was observed from any of the as-implanted samples but it was observed after postimplantation annealings at 650 and 750 °C temperatures. The Er emission was significantly more intense after 650 °C anneals, for Be doped samples, and after 750 °C anneals for undoped samples. It appears on top of a broad background luminescence associated with midgap states. The Er emission intensity was found to scale linearly with the total Er implantation fluence up to Er concentration of ∼1019 Er/cm3. Er precipitation was observed after 750 °C annealing for 1019 Er/cm3 samples, but could be observed for 1020 Er/cm3 Er-doped samples even after a 650 °C anneal. These precipitates are most likely ErAs.

Effect of ion implantation on redistribution of erbium during solid-phase epitaxial crystallization of silicon

It is known that Er-ion implantation and O-ion coimplantation into an amorphized Si layer affect the final Er concentration profile when the layer is subjected to solid-phase epitaxial (SPE) crystallization. This paper discusses how this effect depends on dose, energy, temperature, and the parameters of the segregation model, i. e., the transition layer width L and the coordinate dependence of the segregation coefficient k(x). Increasing the Er implantation dose as well as decreasing the implantation energy and temperature cause L to decrease and the segregation coefficient k to increase more rapidly at the initial stage of SPE crystallization. These phenomena could be due to increased defect formation in the amorphous implanted layer. Additional O coimplantation leads to similar changes in L and k(x), due to Er-O complex formation.

Solubility and damage annealing of Er implanted single crystalline α-Al 2O 3

Er implantation into c-cut sapphire (α-Al 2O 3) was studied using ion beam techniques. Er + ions were implanted at room temperature (RT) and liquid nitrogen (LN) temperature with an energy of 800 keV and fluences in the range of 10 14–10 16 Er/cm 2. At LN temperatures doses above 3 × 10 14 Er/cm 2 create a continuous amorphous layer throughout the implanted region. The epitaxial regrowth of this layer at 1500°C leaves a defect free region and is accompanied by the segregation of a great amount of Er to the surface. The retained Er was randomly incorporated in the α-Al 2O 3 lattice, reaching a maximum concentration of 4 × 10 19 cm −3. In contrast, the implantation of 2 × 10 16 Er/cm 2 at RT only produces a buried amorphous layer near the end of the range. The near surface region, although heavily damaged, remains crystalline. The buried amorphous layer shows an epitaxial recrystallization and some residual defects remain in the region where the Er profile is located. The energy dependence of the dechanneling rate gives an indication that these defects are dislocations. In this case the recrystallization process causes the narrowing of the Er profile with the diffusion of a small amount to the surface. Detailed angular scans along the 〈0 0 0 1〉 and 〈0 2 2 1〉 axes show the presence of Er precipitates aligned with the c-axis.

Structural and Photoluminescence Studies of Er Implanted Lt-GaAs:Be

AbstractCharacteristic 1.54 μm Era3+ emission has been observed from Er-implanted and annealed, low-temperature grown GaAs:Be samples. Cross-sectional transmission electron microscopy (TEM) studies reveal very little structural damage for elevated temperature implants up to an Er total fluence of 1.36 × 1014 Er/cm2. No Er emission was observed from any of the as-implanted samples, while post-implantation annealing optimized the Er emission intensity near 650°C. The Er-emission appears on top of a broad background luminescence peaking near 1500 nm. Significant enhancement of the optically active Er incorporation was achieved when the implantation was carried out at 300TC. The Er emission intensity was found to scale linearly with the Er implantation fluence for samples with an Er concentration up to ∼1019 Er/cm3. The sample with the highest Er concentration (∼1020 Er/cm3) began to show a sublinear dependence. The beginning of Er precipitation was observed after 750°C annealing, but it could even be observed after a 650°C annealing for the highest Er concentration sample. These precipitates are likely ErAs.

Improving the surface behaviors of bearing by adding rare-earth Er implantation

On the basis of our previous work on the implantation mode of Mo + + N +, the strengthening-toughening effect of rare-Earth Er + were investigated using Auger electron spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, X-ray diffraction, electrochemical test, friction and wear test, contact fatigue test, etc. The results indicate that with rational disposition of the energies and doses of Mo + and N +, the additional Er + implantation can not only improve the behaviors of bearing surface, but also enhance the strengthening-toughening efficiency of heavy ions by more than two to four times. It can be concluded that the mode of Mo + + N + + Er + implantation is a relatively ideal method to strengthen and toughen the bearing surface.

Observation of a long relaxation time of the hyperfine field of Dy and Er after recoil implantation in iron and derivation of g-factors of rotational states in 164 Er and 164 Dy

After heavy ion multiple Coulomb excitation of 162,164Dy and 164,166Er and recoil implantation in iron the integral rotations of \gamma--\gamma directional correlations in the static hyperfine field were measured for the 41 +, 61 + and 81 + states. The targets were cooled by liquid nitrogen and magnetized in beam direction by an external magnetic field of ± 4.5 T. With the known g-factors of 166Er (A. Alzner et al., Z. Phys. A 322 (1985) 467) and 162Dy (I. Alfter et al., Z. Phys. A 357 (1997) 13) effective average hyperfine fields were derived. They are smaller than the equilibrium values known from Mossbauer experiments (H.P. Wit et al., Hyp. Interact. 5 (1978) 233; L. Niesen et al., Hyp. Interact. 3 (1977) 109) and increase with the mean lives of the states. A possible explanation of the observed slow relaxation may be the hindrance of exchange within the spin system by the antiferromagnetic coupling between impurity atom and host. The data obtained for 164Er and 164Dy were used to derive the g-factors: g(41 +,164Er) = +0.365(38), g(41 +,164Dy) = +0.251(31), and g(61 +, 164Dy) = +0.272(50).

Fluorescence of Ta_2O_5 thin films doped by kilo-electron-volt Er implantation: application to microcavities

Luminescent layers are prepared by the implantation of kilo-electron-volt Er ions into tantalum pentoxide (Ta(2)O(5)) thin films made by ion plating. The implantation fluences range from 3.3 × 10(14) to 2 × 10(15) ions/cm(2), and the energies range from 190 to 380 keV. Refractive index, extinction coefficient, and losses on guided propagation are investigated. We show that these Er-implanted layers present an absorption as low as that of the nonimplanted films. When optically pumped with an Ar(+) laser (λ = 0.488 μm) beam, implanted films show peaked fluorescence spectra centered near 1.53 and 0.532 μm. We show that the fluorescence intensity is correlated with the intensity of the pump beam in the region where Er ions are implanted. Radiation patterns of Er ions located inside a single layer or inside a Ta(2)O(5)/SiO(2) dielectric stack made by ion plating are also investigated. We show that, in any case, spontaneous emission of Er ions can be spatially controlled.

Comprehensive Rutherford backscattering and channeling study of ion-beam-synthesized ErSi1.7 layers

Heteroepitaxial ErSi1.7 layers with excellent crystallinity (χmin of Er is 1.5%) have been prepared by high-dose 90 keV Er implantation into a Si(111) substrate using channeled implantation. Such an ErSi1.7/Si system offers a rare opportunity to study comprehensively the structure, orientation, and strain using Rutherford backscattering spectrometry and channeling analysis. We found that the minimum yield and width of the [0001] dip of the Er atoms are quite different from that of the Si atoms in the silicide layer. It is confirmed that the azimuthal orientation of the hexagonal ErSi1.7 layer to the cubic Si substrate is ErSi1.7 [0001] ∥ Si[111] and ErSi1.7 {112̄0} ∥ Si {110}, and that the epilayer is compressively strained. Besides, by using the angular scan and image scan, we reveal that the dips of the {101̄0} family are missing for the Si atoms in the epilayer but do exist for the Er atoms in the same epilayer. The reason for this drastic difference is explained by the separate {101̄0} planes and the different steering potential of the Si and Er atoms in ErSi1.7.

A study of the ion implantation damage and annealing behavior in GaSb

The effects of damages produced by implantation of Te, Er, Hg, and Pb ions into undoped (100) GaSb single crystals and their recovery by Rutherford backscattering (RBS)/channeling were investigated. The implantations with dosages in the range of 1013 to 1015 ions/cm2 were carried out at liquid nitrogen temperature, at energies corresponding to a projected range of 447A in GaSb. Near surface damage equivalent to that of an amorphous layer was observed even at lower doses. The samples were annealed at 600°C for different durations, with the Te implanted sample of the lowest dosage exhibiting the best recovery (Χmin = 11%) compared to others. This value of Χmin nearly corresponds to that of the virgin crystal. Examination of the surface morphology as a function of mass, dosage, and annealing duration revealed that it was strongly influenced by the dosage of the implanted ions.

Room temperature light emitting silicon diodes fabricated by erbium ion implantation

In this work we report the fabrication and characteristics of light emitting erbium-doped Si diodes operating at room temperature (RT). These devices were prepared by multiple high energy Er implantation in the active region of a p +-n + Si diode. Oxygen or fluorine implantation in the Er-doped region was also performed in order to properly modify the Er 3+ chemical surrounding. Electroluminescence (EL) at 1.54 μm and at RT has been observed under both forward and reverse bias conditions with the maximum intensity under reverse bias. The temperature dependence of the luminescence revealed that forward-bias EL decreases by about a factor of 30 on going from 100 K to 300 K. An identical temperature dependence is observed in photoluminescence (PL) suggesting that similar excitation mechanisms are responsible for PL and forward-bias EL. In contrast, reverse-bias EL presents a very weak temperature dependence, with a decrease by only a factor of 4 from 100 K to 300 K. These data are reported and possible excitation mechanisms are discussed.

Er 3+ induced infrared active modes in trans-polyacetylene, (CH) x

We have investigated the infrared active modes in undoped and Er 3+ doped trans-(CH) x. The characteristic infrared absorption bands are always observed at 875 cm −1, 1000 cm −1, 1125 cm −1, 1275 cm −1 and 1375 cm −1 for Er 3+ doped trans-(CH) x. Our experiments have shown, for the first time, that the intensity of these absorption bands is obviously increased by the implantation of Er 3+ ions. The intensity of the absorption band at 1375 cm −1 which is associated with the number of charged centers increases with the dopant concentration. It is a charged soliton mode. The increase of other bands (for example at about 875 cm −1, etc) is also caused by Er 3+, but their increases are lower than that of band at 1375 cm −1. The absorption band at 875cm −1 is attributed to the localized phonon mode around a soliton, and hence, we think it is doping induced infrared active mode.

Ion Implantation Damage and Annealing in GaSb

ABSTRACTIon implantation technique is being investigated as an alternate technique for doping GaSb. Hence an understanding of the production and removal of the damage is essential. In this paper, we report on the damages produced by implantation of Te, Er, Hg and Pb ions into undoped (100) GaSb single crystals and their recovery by Rutherford backscattering (RBS)/channeling. The implantations of 1013 to 1013 ions/cm2 in GaSb were done at liquid nitrogen temperature at energies corresponding to the same projected range of 447Å. A comparison of the damage produced by the different ions and their recovery was made by RBS/channeling along <100> axis of GaSb. Near surface damage equivalent to that of an amorphous layer was observed even at lower doses. Upon annealing at 600°C for 30 sec., the Te implanted samples showed best recovery compared to others (Xmin = 11%), the value of Xmin being better than those normally observed in unimplanted Te-doped substrates.

MeV Ion Implantation of Er into LiNbO3

ABSTRACTThe incorporation of Er into LiNbO3 is of great interest for fabricating waveguide lasers and amplifiers. We compare Er diffusion data with the results of Er implantation, performed at 3.6 MeV energy. Even after annealing for 4h at 1060°C, the resulting Er profiles display very good matching to the optical modes. The results of a theoretical gain estimate are presented.

Low-energy erbium implanted Si3N4/SiO2/Si waveguides

Photoluminescence spectroscopy studies of low energy erbium and erbium/oxygen-unplanted silicon-nitride waveguides are compared. Emission spectra show peaks at 1533 and 1548 nm. The optimum annealing temperature is determined to be 1175 o C, yielding lifetimes up to 7 ms and a several decade intensity increase. Er implantation yields more than 40% longer lifetime and higher intensity than Er/O

Low-temperature mesotaxy of ion beam synthesized ErSi2

High doses (7×1016–1.3×1017/cm2) of 170-keV Er+ ions were implanted into single-crystal Si at an implantation temperature of Ti=520 °C. During Er implantation ErSi2 crystallizes as coherent precipitates within a crystalline Si matrix. During the subsequent annealing at 800 °C a discontinuous buried layer of the single crystalline ErSi2 is formed. Implanted and annealed samples were subsequently reimplanted with 170-keV Er+ ions at 250<Ti<520 °C. The second implantation results in a mesotaxial growth of the previously formed buried single-crystal ErSi2 layer for implantation temperatures Ti≳300 °C where ion beam induced, defect mediated diffusion of Er atoms in the Si matrix occurs during the implantation process.

Ion beam induced diffusion and crystallization in high-dose Er implanted Si

High doses (1 × 10 16−1 × 10 17/ cm 2) of 145 and 175 keV Er + ions were implanted into single-crystal Si using implantation temperatures ( T i) between room temperature and 520°C. Implanted samples were subsequently annealed using thermal annealing at 800°C under vacuum as well as a 1 MeV As + ion-beam-assisted annealing (IBAA) at 300°C. During Er + implantation, we find evidence for ion beam induced mobility for T i as low as 300°C. A measurable redistribution of the implanted Er also occurs during the IBAA for Er doses greater than 5 × 10 16/cm −2. During Er implantation at T i > 300°C a polycrystalline ErSi 2 phas T i > 400°C the coherent precipitation of ErSi 2 phase occurs within the crystalline Si matrix. During subsequent thermal anneali samples implanted at T i > 400°C the Er distribution narrows due to Ostwald ripening, and preferential alignment occurs to form a discontinuous buried layer of a single-crystalline Er silicide.