Effect Of Ion Bombardment Research Articles

Enhancing Charge Trapping Performance of Hafnia Thin Films Using Sequential Plasma Atomic Layer Deposition.

We aimed to fabricate reliable memory devices using HfO2, which is gaining attention as a charge-trapping layer material for next-generation NAND flash memory. To this end, a new atomic layer deposition process using sequential remote plasma (RP) and direct plasma (DP) was designed to create charge-trapping memory devices. Subsequently, the operational characteristics of the devices were analyzed based on the thickness ratio of thin films deposited using the sequential RP and DP processes. As the thickness of the initially RP-deposited thin film increased, the memory window and retention also increased, while the interface defect density and leakage current decreased. When the thickness of the RP-deposited thin film was 7 nm, a maximum memory window of 10.1 V was achieved at an operating voltage of ±10 V, and the interface trap density (Dit) reached a minimum value of 1.0 × 1012 eV-1cm-2. Once the RP-deposited thin film reaches a certain thickness, the ion bombardment effect from DP on the substrate is expected to decrease, improving the Si/SiO2/HfO2 interface and thereby enhancing device endurance and reliability. This study confirmed that the proposed sequential RP and DP deposition processes could resolve issues related to unstable interface layers, improve device performance, and enhance process throughput.

Modulating phononic landscapes: The role of silicon ion bombardment in tailoring Si/Si+Ge and SiO2/SiO2+Ge superlattices for advanced neutron superreflector applications

This study investigates the effects of silicon ion bombardment on the phononic properties of Si/Si+Ge and SiO2/SiO2+Ge superlattices to enhance neutron superreflector technology. Through precise ion implantation and Fourier Transform Infrared Spectroscopy (FTIR), we observed significant alterations in transverse and longitudinal optical phonon modes. The Si/Si+Ge system exhibited notable blueshifts and intensity changes, while SiO2/SiO2+Ge showed increased lattice disorder and peak broadening. These findings highlight ion bombardment's potential to optimize phononic landscapes for improved nuclear reactor safety and efficiency via advanced phonon engineering.

Effects of Ar ion bombardment on the structure and properties of β-quartz

β-quartz is an important component that affects the physical and chemical properties of glass-ceramics. The material removal process of ion beam machining is complicated as one of the ultra-precision machining forms. Therefore, it is important to understand the removal mechanism of ion beam machining materials. The methods of molecular dynamics (MD) and first-principles were adopted to investigate the microscopic mechanism of ion beam bombardment of the β-quartz structure. The damage evolution of structures and the evolution of material properties caused by defects respectively from the atomic and electronic levels. Through MD analysis, we find that the random collision between incident ions and matrix atoms can lead to the formation of sputtered atoms. The incidence of ions will increase the disorder degree of the matrix, and the influence on the disorder degree at different depths of the matrix is different. The degree of disorder increases obviously in the range of 50–70 Å from the surface of the matrix. It has a significant impact on the surface topology of the matrix, the number of defects, surface roughness, and matrix density. The results of first-principle calculation show that the refraction, absorption and other characteristics of the system are significantly different with different doping forms, and the energy loss is most affected by substituted doping. And the substituted doping defects have the most significant effects on the structural energy loss. Among, the Ar-substituted O doping structure leads to higher energy loss, and the peak energy loss intensity reaches 5.146. In contrast, the Ar-substituted Si doping structure causes the least energy loss, the intensity is 2.543. This study provides a theoretical basis for the selection of parameters and the realization of ultra-smooth surface in actual ion beam machining.

Foreign Body Reaction to Ion-Beam-Treated Polyurethane Implant.

All artificial materials used for implantation into an organism cause a foreign body reaction. This is an obstacle for a number of medical technologies. In this work, we investigated the effect of high-energy ion bombardment on polyurethane for medical purposes and the reaction of body tissues to its insertion into the mouse organism. An analysis of the cellular response and shell thickness near the implant showed a decrease in the foreign body reaction for implants treated with high-energy ions compared to untreated implants. The decrease in the reaction is associated with the activation of the polyurethane surface due to the formation on the surface layer of condensed aromatic clusters with unbonded valences on the carbon atoms at the edges of such clusters and the covalent attachment of the organism's own proteins to the activated surface of the implant. Thus, immune cells do not identify the implant surface coated with its own proteins as a foreign body. The deactivation of free valences at the edges of aromatic structures due to the storage of the treated implant before surgery reduces surface activity and partially restores the foreign body response. For the greatest effect in eliminating a foreign body reaction, it is recommended to perform the operation immediately after treating the implant with high-energy ions, with minimal contact of the treated surface with any materials.

Enhancing sp3 formation in DLC on low thermal conductivity substrate: Interval deposition minimizing ion energy sensitivity

Depositing sp3-rich diamond-like carbon (DLC) on low thermal conductivity substrates is difficult due to the high sensitivity of sp3 formation to ion energy. This sensitivity is attributed to the heating effect of ion bombardment during plasma-enhanced chemical vapor deposition (PECVD) processing. This study introduced an interval deposition method aimed at minimizing the ion energy sensitivity, thereby achieving sp3-rich DLC deposition and broadening the process window. The variation in sp3 content of deposited DLC showed that the interval deposition can enhance sp3 formation, which is particularly significant when the single deposition duration is ≤1 s and the ratio of interval duration to deposition duration is ≥3. Deposition experiments with varying bias voltages confirmed that the ion energy sensitivity of sp3 formation in DLC can be effectively reduced by the proposed method. The analysis of transient film temperature during the deposition process revealed that this method took effect by limiting the temperature elevation of the film. Performance comparison showed that the adhesion of films to the substrate was improved by 138 % using the interval deposition method, compared to the traditional continuous deposition. This user-friendly and high-tolerance deposition method can significantly advance the application fields of DLC coatings.

Effect of Cluster Ion Bombardment on the Roughly Polished Surface of Single-Crystal Germanium Wafers

Effect of Cluster Ion Bombardment on the Roughly Polished Surface of Single-Crystal Germanium Wafers

Effect of substrate bias on the formation of nanotwin and properties in Cu thin films for advanced packaging technology

Materials with nanotwinned structures have drawn much attention due to their unique properties. The high-density nanotwinned Cu films are generally deposited at room temperature with high deposition rate. In this study, we report nanotwins can be formed in the Cu films at 150 °C with the aid of the ion bombardment effect caused by applied substrate bias. Cu thin films were deposited on Si (100) substrate by the unbalanced magnetron sputtering system using different applied substrate biases ranging from 0 V to −160 V. The results show that, with a suitable applied substrate bias of −120 V, the twinning density of the Cu films can reach over 80 % and exhibit a high hardness of 3.1 GPa. This study provides a concept to tailor the microstructure of the sputtered Cu films by tuning applied substrate biases and realizing the mechanism of substrate bias on the twin formation during deposition.

Effect of V/Mo Atomic Ratio on the Microstructure and Mechanical Properties of MoVCuN Coatings.

To improve the gas ionization ratio, the Mo-V-Cu-N coatings were deposited by pulsed dc magnetron sputtering with assistance from an anode layer ion source, and the influence of the V/Mo atomic ratio was explored with regard to the microstructure and mechanical properties of the coatings. The findings of this study indicated that the MoVCuN coatings exhibited a solid solution phase of FCC B1-MoVN with a prominent (220) preferred orientation, and the deposition rate was found to decrease from 4.7 to 1.8 nm/min when the V/Mo atomic ratio increased. The average surface roughness of the MoVCuN coatings gradually decreased, and the lowest surface roughness of 6.9 nm was achieved at a V/Mo atomic ratio of 0.31. Due to the enhanced ion bombardment effect, the coatings changed from a coarse columnar to a dense columnar crystal structure, and promoted grain refinement at higher V/Mo atomic ratios, contributing to a gradual improvement in the compressive residual stress, hardness and adhesion strength of the coatings.

Microstructure and Mechanical Properties of AlTiVCuN Coatings Prepared by Ion Source-Assisted Magnetron Sputtering.

The AlTiVCuN coatings were deposited by magnetron sputtering with anode layer ion source (ALIS) assistance, and the microstructure and mechanical properties were significantly affected by the ion source power. With increasing the ion source power from 0 to 1.0 kW, the deposition rate decreased from 2.6 to 2.1 nm/min, and then gradually increased to 4.0 nm/min at 3.0 kW, and the surface roughness gradually decreased from 28.7 nm at 0 kW to 9.0 nm at 3.0 kW. Due to the enhanced ion bombardment effect, the microstructure of the coatings changed from a coarse into a dense columnar structure at 1.0 kW, and the grain size increased at higher ion source powers. All the coatings exhibited c-TiAlVN phase, and the preferred orientation changed from the (220) to the (111) plane at 3.0 kW. Due to the low Cu contents (1.0~3.1 at.%), the Cu atoms existed as an amorphous phase in the coatings. Due to the microstructure densification and high residual stress, the highest hardness of 32.4 GPa was achieved for the coating deposited at 1.0 kW.

Comparison of the Optical Properties of Different Dielectric Materials (SnO2, ZnO, AZO, or SiAlNx) Used in Silver-Based Low-Emissivity Coatings

This work analyzed and compared the optical and photoenergetic properties of low-emissivity coatings made from various dielectric materials deposited through magnetron sputtering following a systematic, comparable method. Different multilayer structures of silver-based low-emissivity coatings were studied using SnO2, ZnO, SiAlNx, and aluminum-doped zinc oxide (AZO, which is inherently a semiconductor, but it fulfils an optical dielectric function in this type of structure). The properties of the coatings were determined by spectrophotometric and sheet resistance measurements. Coatings with AZO as the dielectric layers obtain the best photoenergetic performance because silver growth is more efficient on AZO. We also studied the effect of ion bombardment on AZO and SiAlNx in an attempt to obtain a better low-emissivity coating, achieving better results when etching the dielectric layer with an ion gun. Regarding the structures’ visible transmission, the oxides produced better transmission results. Based on the above, we concluded that AZO had the best optical and photoenergetic properties in our deposition system, observing, in the best-case scenario, improvements in emissivity from 0.083 with SnO2 to 0.058 with AZO and to 0.052 using an ion beam on AZO and improvements in visible transmission from 81.9% with SnO2 to 86.8% with AZO.

Application of dual-layer polysilicon deposited by PECVD in n-type TOPCon solar cells

Plasma-enhanced chemical vapor deposition (PECVD) has attracted much attention in the current mass-production of n-type tunnel oxide passivated contact (TOPCon) crystalline silicon (c-Si) solar cells because of the advantages of fast film forming rate and compatibility with in-situ doping. However, the PECVD technology is limited by the effect of ion bombardment on the ultra-thin SiO2 layer during gas ionization, together with the inevitable front wrap-around poly-Si. Here, the dual-layer poly-Si stack made up of the intrinsic poly-Si(i) and in-situ P-doped poly-Si(n+) has been achieved by adjusting the deposition power, pulse voltage duty cycle, and flow rate of the PH3, which effectively protects the tunneling SiO2 layer through the weakened ion bombardment to improve the interface passivation and contact resistivity. We have demonstrated that the pinhole density is an important reason for the thinner SiO2 layer optimized less than 1.0 nm. More importantly, the conversion efficiency of n-type TOPCon c-Si solar cells can be improved by more than 0.10% and 0.15%, respectively, by the combination of the dual-layer poly-Si stack and wrap-around poly-Si removal compared with the single-layer poly-Si counterpart with the same thickness.

Effect of Low-Energy Ion Bombardment on the Texture and Microstructure of Platinum Films

Effect of Low-Energy Ion Bombardment on the Texture and Microstructure of Platinum Films

Effect of low-energy ion bombardment on structural and optical properties of gold functionalized hBN nanosheets

This work reports the effect of low-energy ion (30 KeV Si−1) bombardment on the structural and optical properties of gold-functionalized hexagonal boron nitride (Au-hBN) nanosheets. FE-SEM and XRD results indicate the successful synthesis of highly crystalline Au-hBN nanosheets. The grain size modulation and strain variation in Au-hBN nanosheets with increasing ion fluence clearly indicate defect-induced structural modifications. The optical properties of Au-hBN are investigated by Raman and UV–vis absorption spectroscopy. A systematic drop in the band gap and gradual rise in the Urbach energy of Au-hBN nanosheets with increasing fluence is observed. In addition, the FTIR results reveal the growth of cBN, eBN and wBN phases after irradiation. The theoretical simulations are done to study the defect formation and estimate the damage yields. The experimental and computational results establish the efficacy of the low-energy ion bombardment approach in systematically altering the structural and optical behavior of Au-hBN nanosheets.

Helium plasma immersion ion implantation studies of tungsten and tungsten heavy alloys for fusion plasma facing components

Plasma fusion devices will require plasma-facing components (PFCs) which can withstand the extreme environment at the edge of a hot fusion plasma. Despite the excellent properties of tungsten(W) as a hard refractory metal, adverse effects such as embrittlement, melting, and morphological evolution have been observed in W when it is bombarded by a high-fluence of low-energy ions including helium. This study investigates the effect of helium ion bombardment on pure tungsten and a tungsten heavy alloy (W-HA)(NAECOMET 1000). Pure tungsten and NAECOMET 1000 samples were implanted with 3 keV helium ions with fluences ranging from to , using Plasma Immersion Ion Implantation (PIII). After PIII treatment, samples were analysed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), which revealed differences in surface morphology and topography. Although the melting and cracking of the Ni/Cu binder phase in the NAECOMET 1000 samples was seen under all implantation conditions, the Ni/Cu presence did somewhat slow the formation of W fuzz in comparison to pure tungsten. X-ray diffraction (XRD) studies showed peak shifts increasing with helium ion fluence for both the pure W and NAECOMET 1000 samples, as well as increase in mean crystallite size, confirming the distortion of the lattice. XPS compositional analysis showed a strong oxidation (>97) near the metal surface, after helium PIII treatment, for both pure W and NAECOMET 1000 W-HA samples. Some conclusions about the potential suitability of W-HA materials for fusion plasma PFCs are drawn.

Microstructure and mechanical properties of nanomultilayered AlTiN/Cu coatings prepared by a hybrid system of AIP and PDCMS

Due to its excellent lubricity and immiscibility with nitride phase, Cu has been added to nitrides to form a typical nanomultilayer structure. In this work, a hybrid deposition of AIP and PDCMS was applied to synthesize the multilayered AlTiN/Cu coatings, and the relationship between microstructure and mechanical properties was explored. The Cu-free AlTiN coating exhibited a c-TiAlN phase with a strong (200) preferred orientation. After adding Cu layer, the microstructure changed from a dense columnar structure into a featureless structure and then a fine-grained structure. As the Cu layer thickness reached 5.1 nm, the AlTiN/Cu(18.4 at.%) coating showed a double-phase of c-TiAlN and c-Cu. The thickness modulation period of Cu/AlTiN sublayer exhibited an excellent linear relationship with the content ratio of Cu/(Al + Ti). After adding Cu, the ion bombardment effect was weakened, the AlTiN/Cu(2.9 at.%) coating exhibited the lowest surface roughness of 18.9 nm, and the hardness gradually decreased from 34.6 to 13.2 GPa, accompanied by a relaxation of residual stress. Due to a high H/E * ratio, a maximum adhesion strength of 83.0 N was obtained at 2.9 at.% Cu.

Effect of substrate bias on the microstructure and mechanical and tribological properties of ZrNbTiMo refractory high entropy alloy film

ZrNbTiMo refractory high entropy alloy (RHEA) films were deposited via direct current magnetron sputtering under different substrate biases (0 to −200 V). The phase structure, microstructure, surface roughness, mechanical, and tribological properties of the ZrNbTiMo RHEA films were investigated. Results show that the ZrNbTiMo RHEA films exhibit a single body-centered-cubic structure. As the substrate bias increases, the preferred orientation of the ZrNbTiMo RHEA films changes from (110) to (200). The surface roughness of the films decreases from 3.9 nm to 2.0 nm then increases to 4.1 nm. The growth mechanism can be understood as the result of the interaction of ion incident direction, ion bombardment effect, and atom diffusion ability which are controlled by the substrate biases. The hardness of the films increases from 6.8 GPa (0 V) to 21.3 GPa (−200 V). The maximum fracture toughness (0.968 MPa × m1/2) is obtained under −200 V. The wear resistance does not exhibit a monotonically increasing trend with the increase of substrate bias. The films deposited under −50 and − 100 V have lower values of H/E and H3/E2, but these films still possess better wear resistance. The wear mechanism of the ZrNbTiMo RHEA films is investigated in detail from the microstructure perspective.

Effects of substrate bias on the sputtering of high density (111)-nanotwinned Cu films on SiC chips

This article presents a study of the influence of the substrate bias on the microstructure, preferred orientation, and mechanical and electrical properties of nanotwinned Cu film. The formation of a nanotwinned structure and (111) surface orientation can be properly controlled by applied substrate bias. High density nanotwinned structures were introduced into Cu films sputtered on SiC substrates with over 90% of (111)-orientation at − 150 V. Densely packed Cu nanotwins were observed within the columnar grains stacked up on each other along the film growth direction, with an average twin spacing of 19.4 nm. The Cu films deposited on SiC substrate via bias sputtering had surface roughness of 8.6 to 15.8 nm. The resistivity of the copper nanotwinned films sputtered with various substrate biases varied. The optimal indentation, 2.3 GPa, was found in the nanotwinned Cu film sputtered with a bias voltage of − 150 V. The effects of Ar ion bombardment on microstructure, surface morphology and properties are further discussed.

Measuring sub-surface spatially varying thermal conductivity of silicon implanted with krypton

The thermal properties of semiconductors following exposure to ion irradiation are of great interest for the cooling of electronic devices; however, gradients in composition and structure due to irradiation often make the measurement difficult. Furthermore, the nature of spatial variations in thermal resistances due to spatially varying ion irradiation damage is not well understood. In this work, we develop an advancement in the analysis of time-domain thermoreflectance to account for spatially varying thermal conductivity in a material resulting from a spatial distribution of defects. We then use this method to measure the near-surface (≲1 μm) thermal conductivity of silicon wafers irradiated with Kr+ ions, which has an approximate Gaussian distribution centered 260 nm into the sample. Our numerical analysis presented here allows for the spatial gradient of thermal conductivity to be extracted via what is fundamentally a volumetric measurement technique. We validate our findings via transmission electron microscopy, which is able to confirm the spatial variation of the sub-surface silicon structure, and provide additional insight into the local structure resulting from the effects of ion bombardment. Thermal measurements found the ion stopping region to have a nearly 50× reduction in thermal conductivity as compared to pristine silicon, while TEM showed the region was not fully amorphized. Our results suggest this drastic reduction in silicon thermal conductivity is primarily driven by structural defects in crystalline regions along with boundary scattering between amorphous and crystalline regions, with a negligible contribution being due to implanted krypton ions themselves.

Effects of He-ion bombardment on the ferroelectric and dielectric properties of BaHf0.17Ti0.83O3 films

Focused helium ion bombardment provides an effective means to modify the properties of ferroelectric materials. This work systematically investigates the effect of helium ion bombardment on the structural, ferroelectric, and dielectric properties of relaxor BaHf0.17Ti0.83O3 thin films at different bombardment doses in the range of 1 × 1012 to 7 × 1015 ions/cm2. The films show more defects and slightly expanded out-of-plane lattice parameters with an increase in dose. Despite helium ion bombardment introducing more defects and structural disorder in the system, the bombardment-induced dipole polarization leads to enhanced ferroelectricity. Our findings highlight energetic helium ion bombardment as an effective way to enhance the ferroelectricity of relaxor materials.

Correlating Deposition Parameters with Structure and Properties of Nanoscale Multilayer (TiSi)N/CrN Coatings

Multilayer (TiSi)N/CrN coatings were fabricated through vacuum-arc deposition by applying the arc currents of (100 ÷ 110) A on TiSi cathode and (80 ÷ 90) A on Cr cathode, negative bias potential connected to the substrate holder of –(100 ÷ 200) V and reactive gas pressure of (0.03 ÷ 0.6) Pa. Applying a negative bias voltage on substrates enhanced the ion bombardment effect, which affected the chemical compositions, phase state, mechanical and tribological properties of (TiSi)N/CrN coatings. Obtained results indicated that (TiSi)N/CrN coatings with Si content ranging from 0.53 to 1.02 at. % exhibited a high hardness level of (22.1 ÷ 31.1) GPa accompanied with a high Young’s modulus of (209 ÷ 305) GPa, H/E* level of (0.080 ÷ 0.100), H3/E*2 level of (0.15 ÷ 0.33) GPa, and the friction coefficient of 0.35. Values of critical loads at dynamic indentation, changes in friction coefficient and level of acoustic emission signal evidence the high adhesive strength of (TiSi)N/CrN coatings, which allows recommending them to increase cutting tool performance.