Implantation-induced Defects Research Articles

Effect of implantation temperature on exfoliation of H2+-implanted Si

The effect of implantation temperature of crystalline silicon implanted with hydrogen on exfoliation was investigated. The samples were analyzed by Raman scattering spectroscopy, optical microscopy and transmission electron microscopy. Our experiment shows that the concentrations of implantation-induced defects and hydrogen decrease with the implantation temperature. Compared to the implantation at 573 K and 773 K, (100) platelets are preferentially nucleated when the sample was implanted at room temperature (RT), while {111} platelets are preferentially nucleated for the elevated temperature implantation. After annealing at 773 K, blisters and exfoliation occur for the sample implanted at RT but not the sample implanted at 573 K. Microstructure shows a microcrack in the damaged layer for the sample implanted at RT. After annealing at 973 K, blisters and exfoliation occur for the samples implanted at RT, 573 K and 773 K. The exfoliation mean size increases, but the exfoliation density decreases with the implantation temperature. Microstructure shows a microcrack in the damaged layer for the samples implanted at RT, 573 K and 773 K. The depth of the microcrack is related to the implantation temperature. The effects of implantation temperature on dislocation loops, platelet nucleation and growth were investigated.

Photoluminescence of implantation-induced defects in SiO2:Pb+ glasses

The luminescence of quartz glass with implanted Pb+ ions is investigated by time-resolved photoluminescence spectroscopy under synchrotron excitation. It is established that the glass layer modified with ions represents a microheterogeneous medium with a variable content of implanted ions predominantly in the form of Pb2+. Three different types of emission centers are detected that are created by radiation-induced defects of the SiO2 matrix and localized electronic states of the amorphous lead-silicate phase.

Electrical characterisation and predictive simulation of defects induced by keV Si+ implantation in n-type Si

In this work, we focused on the analysis of implantation-induced defects, mainly small interstitial clusters (ICs) and {311} defects introduced in n-type Si after ion implantation using deep level transient spectroscopy (DLTS). Silicon ions (at 160 keV or 190 keV) of fluences ranging from (0.1–8.0) × 1013 cm−2 have been implanted into n-type Si and annealed at temperatures between 500 °C and 800 °C specifically to create small ICs or {311}s rod-like defects. In samples dominated by small ICs, DLTS spectra show prominent deep levels at Ec − 0.24 eV and Ec − 0.54 eV. After increasing the fluence and temperature, i.e., reducing the number of small ICs and forming {311} defects, the peak Ec − 0.54 eV is still dominant while other electron traps Ec − 0.26 eV and Ec − 0.46 eV are introduced. There were no observable deep levels in reference, non-implanted samples. The identity and origin of all these traps are interpreted in conjunction with recently developed predictive defect simulation models.

Chemical effect of Si+ ions on the implantation-induced defects in ZnO studied by a slow positron beam

Undoped ZnO single crystals were implanted with 300 keV Si+ ions to a dose of 6 × 1016 cm−2. A combination of X-ray diffraction (XRD), positron annihilation, Raman scattering, high resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) was used to study the microstructure evolution after implantation and subsequent annealing. A very large increase of Doppler broadening S parameters in Si+-implanted region was detected by using a slow positron beam, indicating that vacancy clusters or microvoids are induced by implantation. The S parameters increase further after annealing up to 700 °C, suggesting agglomeration of these vacancies or microvoids to larger size. Most of these defects are removed after annealing up to 1100 °C. The other measurements such as XRD, Raman scattering, and PL all indicate severe damage and even disordered structure induced by Si+ implantation. The damage and disordered lattice shows recovery after annealing above 700 °C. Amorphous regions are observed by HRTEM measurement, directly testifies that amorphous phase is induced by Si+ implantation in ZnO. Analysis of the S – W correlation and the coincidence Doppler broadening spectra gives direct evidence of SiO2 precipitates in the sample annealed at 700 °C, which strongly supports the chemical effect of Si ions on the amorphization of ZnO lattice.

Stability of the Fe3 + state in ZnO

We have applied implantation of radioactive 57Mn + (T1/2 = 1.5 min) at the ISOLDE facility at CERN with 50–60 keV energy to fluences 760 K or storage at room temperature for 12 months, after which they show dominantly the Fe2 + state for <2 × 101057Mn/cm2 implantations. These findings are discussed in terms of diffusion and/or annihilation of implantation-induced defects.

Multiple implantation and multiple annealing of phosphorus doped germanium to achieve n-type activation near the theoretical limit

Full activation of n-type dopant in germanium (Ge) reaching to its solid solubility has never been achieved by using ion implantation doping technique. This is because implantation of dopants always leaves defects such as vacancy and interstitials in the Ge crystal. While implantation-induced defects are electrically neutral for the most of semiconductor materials, they are electrically positive for Ge resulting in compensation of n-type dopants. In this Letter, we verified that 5 × 1019 P/cm3 is the maximum active concentration, which can be fully activated in germanium “without leaving implantation damage” per implantation/annealing cycle. The repetition of implantation and annealing of phosphorous (P) with the concentration of 5 × 1019 cm−3 leads to the activation of 1 × 1020 P/cm3 close to its solid solubility limit of 2 × 1020 P/cm3.

Structural recovery of ion implanted ZnO nanowires

Ion implantation is an interesting method to dope semiconducting materials such as zinc oxide provided that the implantation-induced defects can be subsequently removed. Nitrogen implantation followed by anneals under O2 were carried out on zinc oxide nanowires in the same conditions as in a previous study on bulk ZnO [Perillat-Merceroz et al., J. Appl. Phys. 109, 023513 (2011)], allowing a direct comparison of the defect recovery mechanisms. Transmission electron microscopy and cathodoluminescence were carried out to assess the effects of nitrogen implantation and of subsequent anneals on the structural and optical properties of ZnO nanowires. Defect recovery is shown to be more effective in nanowires compared with bulk material due to the proximity of free surfaces. Nevertheless, the optical emission of implanted and annealed nanowires deteriorated compared to as-grown nanowires, as also observed for unimplanted and annealed nanowires. This is tentatively attributed to the dissociation of excitons in the space charge region induced by O2 adsorption on the nanowire surface.

The local generation and recombination lifetime based on forward diode characteristics diagnostics

This paper is proposed to extract the local carrier generation and recombination lifetime from forward characteristics of diode. The different geometry p–n junctions have been fabricated by a standard CMOS technology. Among a variety process steps, implantation step may generate defects. Therefore, the local implantation-induced defects have been studied from the defect activation energy, which has been obtained from the ratio of the local carrier generation and recombination lifetime. The forward current–voltage (I–V) and high frequency capacitance–voltage (C–V) characteristics of p–n junctions have been measured in order to obtain the local carrier generation and recombination lifetime. The calculated activation energy from this method gave reasonable values comparing with the ones obtained from the Arrhenius plot of the reverse current.

Surface damage versus defect microstructures in He and H ion co-implanted Si3N4/Si

Cz n-type Si (100) wafers with a top Si3N4 layer of about 170nm in thickness were sequentially implanted with 40keV He ions at a fluence of 5×1016/cm2 and 35keV H ions at fluences of 1×1015, 5×1015 and 1×1016/cm2, respectively. Creation and evolution of surface damage as well as micro-defects have been studied. Our results clearly show that production of surface damage depends strongly on both the H implant fluence and annealing temperature. Only blistering or localized exfoliation of the top Si3N4 layer has been observed for post H implantation at fluences of 1×1015 and 5×1015/cm2 upon 800°C annealing. However, serious surface exfoliation has been found for the 1×1016/cm2 H co-implanted samples after annealing at 450°C and above. The exfoliation occurs at a depth of about 360nm from the surface, which is obviously larger than the He or H ion range. Moreover, the exfoliated craters show clear two-step structures. Cross-sectional transmission electron microscopy (XTEM) observations reveal formation of micro-cracks in Si bulk and along the original interface, which is mainly responsible for the observed surface phenomena. The formation mechanism of micro-cracks has been discussed in combination of He and H implant-induced defects, impurities as well as their interactions upon annealing.

Status of p-on-n Arsenic-Implanted HgCdTe Technologies

In this paper recent developments made by the French Atomic Energies and Alternative Energies Commission (CEA) at the Electronics and Information Technology Laboratory (LETI) on the fabrication of planar p-on-n HgCdTe photodiodes are reported. Results obtained on long-wavelength infrared (LWIR) liquid-phase epitaxy (LPE) and mid- and short-wavelength infrared (MWIR/SWIR) molecular beam epitaxy (MBE) have been previously published. For these photodiodes, p-type doping is obtained by arsenic implantation followed by diffusion and activation under Hg-overpressure annealing. The active layer is n-type doped by indium incorporation during growth. Control of the p-on-n junctions is one of the key points of this technology, requiring good knowledge of the arsenic implantation and diffusion and the evolution of implantation-induced defects. Concerning implantation, the impact of dose (from 2 × 1014 at./cm2 to 2 × 1015 at./cm2) and energy (from 50 keV to 500 keV) on As profiles is considered. The profiles after implantation are modeled using Pearson IV moments. Realistic descriptions of arsenic distributions are obtained, and the evolution of moments with implantation conditions is fitted. In addition, implantation damage is examined by transmission electron microscopy (TEM) and the evolution of defects is studied depending on implantation conditions and Hg-overpressure annealing. Previous results obtained on 30-μm-pitch LPE LWIR and MBE MWIR/SWIR showed state-of-the-art detector performance. Since these first results, progress has been made to decrease the pixel pitch to 15 μm and increase the focal-plane array (FPA) format. In this way, 640 × 512 LPE LWIR FPAs have been processed and characterized. In addition we report results obtained on our first p-on-n very long-wavelength infrared (VLWIR) photodiode fabricated at CEA–LETI with λc = 13.35 μm at 50 K. These latest results demonstrate the viability of our technology and materials.

Enhanced annealing of implantation-induced defects in 4H-SiC by thermal oxidation

Annealing of the prominent Z1/2 defect in 4H-SiC has been studied after thermal treatment in N2 and O2 atmospheres at 1150 °C subsequent to implantation with MeV Si-ions to doses in the range of (1–4)×108 cm−2. The annealing rate is found to be significantly enhanced under oxidizing conditions, while in N2 atmosphere Z1/2 remains stable. Hence, a substantial lowering of the annealing temperature required for defect removal in 4H-SiC doped by ion-implantation may be expected using oxidizing annealing atmosphere. Concentration versus depth profiles of Z1/2 clearly show that it is annihilated by defect species injected from the SiO2/4H-SiC interface during oxidation. The injection rate of the in-diffusing species is found to be about (1.2±0.2)×106 cm−2 s−1, and the concentration ratio of the injected species relative to the native atoms originally present in the oxidized volume is ∼1×10−7. A model where the annihilating species are injected from the surface with a diffusion coefficient of about 10−8 cm2/s yields excellent agreement with the experimental data.

He and H-implanted CLAM steel investigated by positron-annihilation spectroscopy

The distribution and nature of defects induced by H ion, He ion, and mixed-beam H and He ion implantation in China low-activation martensitic (CLAM) steel were studied by positron-annihilation spectroscopy. The evolution of vacancy-type defects in the CLAM steel was detected when the ion implantation dosage was varied. Significant differences in the S parameter-positron energy profile in response to the different implanted ions were observed. The implantation-induced defects were analyzed using VEPFIT. One type of defect was found in all ion-implanted samples.

Non-melt Laser Thermal Annealing of Shallow Boron Implantation for Back Surface Passivation of Backside-Illuminated CMOS Image Sensors

ABSTRACTBack surface passivation is one of the major challenges in the backside illuminated sensor technology. Ion implantation followed by non-melt pulsed Laser Thermal Annealing (LTA) has been identified as a promising candidate to address this issue. In this work, a shallow B-doped layer is implanted at the backside, further activated using LTA in the non-melt regime. LTA process effectiveness in terms of crystal damage recovery as well as dopant diffusion and activation is studied through room-temperature photoluminescence, Secondary Ion Mass Spectroscopy and four-point probe sheet resistance. These studies demonstrate that non-melt LTA with multiple pulses induces high activation without visible diffusion with an effective curing of the implantation-induced crystalline defects. This is made possible thanks to a submicrosecond process timescale coupled to a reasonable number of shots as shown by thermal simulations and simple diffusion estimations.

Trapping and release of helium in tungsten

The behavior of tungsten under irradiation and helium implantation is a major stake of the material-related issues of fusion reactors. In this perspective the fate of helium in tungsten was studied by mean of several characterization techniques. The aim of this study is to highlight the trapping mechanisms of helium in tungsten and their correlation with implantation-induced defects. Helium was implanted into tungsten at two different energies, 0.32 and 60 keV. The helium was studied as a function of temperature by using nuclear reaction analysis. The migration propensity of helium was correlated with the release rate of helium after annealing at a given temperature. In addition, the helium trapping sites and evolution with post-implantation annealing was investigated using Doppler-Broadening Positron Annihilation Spectroscopy. It has been shown that the release, and so the migration, of helium is guided by the concentration of implantation-induced defects and the nature of the helium traps created during the implantation.

Optical properties of In xGa 1−xP/InP grown at high fluence Ga + implantation on InP using focused ion beam

Single-crystalline InP(1 0 0) substrate was implanted by 30 keV Ga + ions with fluences of 1 × 10 16–1.5 × 10 17 cm −2 followed by post-annealing treatment at 750 °C to recover implantation-induced structural defects and activate dopants into the lattices. The optical property, composition, and microstructure of the Ga +-implanted InP were studied by Raman spectroscopy and transmission electron microscopy (TEM). Raman spectra show that the In x Ga 1− x P phase is formed at a critical fluence of 7 × 10 16 cm −2. The newly grown phase was identified with the appearance of Ga rich TO InP and In rich TO GaP modes of a random alloy in the 1 bond-2 phonon mode configuration along with TEM structural identification.

Si Ion Implantation-Induced Defect Photoluminescence in Silica Films

Dry and wet oxidation silica films doped with silicon ions were prepared using metal vapor vacuum arc (MEVVA) ion source implanter. The does of Si ion beams were kept constant at 3×1016 /cm2 and the energy varied from 42KeV to 70KeV. Five photoluminescence (PL) bands at the wavelength of 560nm, 580nm, 620nm, 650nm and 730nm have been observed at room temperature in all samples. The results of XRD showed none of Si nanocrystals were formed in the as-implanted silica films and originations of the PL bands were defects introduced by implantation. The 560nm PL band originated from oxygen surplus defect small peroxy radical (SPR), whereas the PL bands which ranges from the wavelength of 620nm to 730nm were attributed to non bridge oxygen hole center (NBOHC). Elevating implantation energy resulted in intensity increasing of 560nm PL band of dry oxidation samples but had inverse effects on wet oxidation samples. Influence mechanism of implantation energy on the defect photoluminescence was discussed in this article.

Swelling or erosion on the surface of patterned GaN damaged by heavy ion implantation

Wurtzite undoped GaN epilayers (0 0 0 1) was implanted with 500 keV Au + ions at room temperature under different doses, respectively. Ion implantation was performed through photoresist masks on GaN to produce alternating strips. The experimental results showed that the step height of swelling and decomposition in implanted GaN depended on ion dose and annealing temperature, i.e., damage level and its evolution. This damage evolution is contributed to implantation-induced defect production, and defect migration/accumulation occurred at different levels of displacement per atom. The results suggest that the swelling is due to the formation of porous structures in the amorphous region of implanted GaN. The decomposition of implanted area can be attributed to the disorder saturation and the diffusion of surface amorphous layer.

Formation of cBN nanocrystals by He + implantation into hBN

The structural modifications of polycrystalline hexagonal boron nitride implanted with He + beams at energies between 200 keV and 1.2 MeV to fluences of 1.0 × 10 17 ions cm − 2 were investigated using micro-Raman spectroscopy. The measured Raman spectra show evidence of implantation-induced structural transformations from the hexagonal phase to nanocrystalline cubic boron nitride, rhombohedral boron nitride and amorphous boron nitride phases. The first-order Longitudinal-Optical cubic boron nitride phonon was observed to be downshifted and asymmetrically broadened and this was explained using the spatial correlation model coupled with the high ion implantation-induced defect density.

Specific features of erbium ion photoluminescence in structures with amorphous and crystalline silicon nanoclusters in silica matrix

Photoluminescence properties of the structures of amorphous and crystalline silicon nanoclusters with average sizes no larger than 4 nm in an erbium-doped silicon dioxide matrix were studied. It was found that the photoluminescence lifetime of Er3+ ions at a wavelength of 1.5 μm decreases from 5.7 to 2.0 ms and from 3.5 to 1.5 ms in samples with amorphous nanoclusters and with nanocrystals, respectively, as the Er3+ concentration increases from 1019 to 1021 cm−3. The decrease in the erbium photoluminescence lifetime with the ion concentration is attributed to the effects of concentration-related quenching and residual implantation-induced defects. The difference between lifetimes for samples with amorphous and crystalline nanoclusters is interpreted as the effect of different probabilities of energy back transfer from Er3+ ions to the solid-state matrix in the structures under consideration.

Fe-implanted SiC as a potential DMS: X-ray diffraction and rutherford backscattering and channelling study

Single crystalline (0 0 0 1)-oriented 6H-SiC samples were implanted at 380 °C with low-energy Fe ions (in the 100 keV range) with the aim of synthesizing so-called diluted magnetic semiconductors. X-ray diffraction and Rutherford backscattering spectrometry and channeling are used to study the microstructural changes in these Fe-implanted SiC crystals submitted to furnace annealing and laser processing, both treatments being performed in order to eliminate the implantation-induced defects.