Ion-implanted Devices Research Articles

Damage evolution behavior of TiN/Ti multilayer coatings under high-speed impact conditions

The erosion of compressor blades by solid particles brings huge safety hazards to aero engines. The application of erosion-resistant hard coating has become a good solution to protect titanium alloy blades. In this work, TiN monolayer and TiN/Ti multilayer coatings were prepared on Ti-6Al-4V alloy using a magnetic filtered cathode vacuum arc system (FCVA) and a metal vapor vacuum arc (MEVVA) ion implantation device. The mechanical properties of the coatings were evaluated by nanoindentation and scratch tests. The damage evolution behavior and mechanism of TiN monolayer and TiN/Ti multilayer coatings are studied by single-particle impact test and finite element simulation. The results show that the fracture toughness of TiN monolayer coating is lower than that of TiN/Ti multilayer coating; TiN/Ti multilayer coatings exhibit good erosion resistance. The main reason lies in that the Ti layer dissipates part of impact energy by plastic deformation and reduces the tensile stress. The interfaces in the multilayer coating inhibited the propagation of cracks.

Optimized Si-Based Blocked Impurity Band Detector Under Alternative Operational Mode

In this paper, alternative operational mode (AOM) of Si-based blocked impurity band (BIB) detectors is thoroughly investigated. The basic structure of the detector evolves from the prototype of the ion-implanted BIB detector, which is potentially compatible with CMOS processes. Benefiting from lower dark current, the detectivity of ion-implanted devices studied in this work is comparable with the Si BIB detectors ever reported. For ion implantation devices, a peak blackbody detectivity of ${5} \times {10}^{{12}}$ cm $\cdot $ Hz1/2/W (background temperature T = 40 K) occurs at 2 V under AOM. These merits make the ion-implanted device a powerful candidate for a wide range of applications from infrared to terahertz band. By analyzing the carrier distribution and the band structure in different functional regions of the device at the measured temperature, depletion junction formed in the region of active layer near active layer/cathode interface side is deduced when the device is operated under AOM. The theory is successfully used to interpret experimental data, including the detectivity comparable to the epitaxial device, significantly reduced dark current.

Development and experimental study of large size composite plasma immersion ion implantation device

Plasma immersion ion implantation (PIII) overcomes the direct exposure limit of traditional beam-line ion implantation, and is suitable for the treatment of complex work-piece with large size. PIII technology is often used for surface modification of metal, plastics and ceramics. Based on the requirement of surface modification of large size insulating material, a composite full-directional PIII device based on RF plasma source and metal plasma source is developed in this paper. This device can not only realize gas ion implantation, but also can realize metal ion implantation, and can also realize gas ion mixing with metal ions injection. This device has two metal plasma sources and each metal source contains three cathodes. Under the condition of keeping the vacuum unchanged, the cathode can be switched freely. The volume of the vacuum chamber is about 0.94 m3, and maximum vacuum degree is about 5 × 10−4 Pa. The density of RF plasma in homogeneous region is about 109 cm−3, and plasma density in the ion implantation region is about 1010 cm−3. This device can be used for large-size sample material PIII treatment, the maximum size of the sample diameter up to 400 mm. The experimental results show that the plasma discharge in the device is stable and can run for a long time. It is suitable for surface treatment of insulating materials.

Gamma irradiated electron paramagnetic resonance response of carbonate ion implanted hydroxyapatite

In this work, synthetic nano-structure hydroxyapatite samples were doped by carbonate ions with 80 keV of energies during different times of 4, 8, 16, and 24 minutes using an ion implantation device. All the samples were irradiated with the 60Co gamma ray source at different absorbed doses of 5, 10, 20, and 50 kGy and subjected to electron paramagnetic resonance measurements, subsequently. The electron paramagnetic resonance signal intensities were constructed as a function of radiation dose and were compared with the results of non-implanted one, and were studied from dosimetric point of view. The obtained results show a considerable increment in electron paramagnetic resonance signal intensity of the samples which were implanted for 24 minutes.

ФіЗИКО-ТЕХНОЛОГіЧНі АСПЕКТИ БАГАТОЗАРЯДНОї іМПЛАНТАЦії АРСЕНіД ГАЛіЮ В СТРУКТУРАХ ПРИЛАДіВ і СХЕМ

The development of microelectronics in Ukraine was accompanied by altering of four generations of ion implantation equipment. Nowadays, ion implantation devices of three classes of small and medium doses, high doses and high energies, are used for micro-, opto- and nanoelectronics. For many years, double-chamber ''Vezuviy-3'' and its modified version ''Vezuviy-3M'', with drum-type receiving units and electrostatic ion beam scanning, have been the most popular among light-dose devices. Despite its reasonable price, it has high efficiency (300 plates mm per hour), high implantation heterogeneity ( over a plate) and performance reliability (availability factor was). High dose devices ''Vezuviy-4'' and ''Vezuviy-8'' of the 70-80s and their modified versions, with combined mechanical and electro-magnetic scanning, were produced using ion beam post-acceleration and receiving unit, which was both at high and ground potentials. The development of high-energy implantation was based on using multi-charge ions (2-4) of the main dopants. The energies below 2 MeB at total accelerating voltage 400 KeB and ion beam current below 1mА and below 0,3 mА were recorded in one of modified versions of high-energy implantation ''Vezuviy-9''. It was the starting point of decreasing radiation defects in BIC structures.

Nanometric AlGaN/GaN HEMT Performance with Implant or Mesa Isolation

AlGaN/GaN 70-nm-gate high-electron mobility transistors (HEMTs) fabricated using either ion implantation or conventional mesa isolation are compared. Although the resulting devices display comparable dc characteristics, the isolation process influences the RF and pulsed I-V characteristics. Although others have described implant-isolated GaN HEMTs, published reports focused on limited performance metrics, such as the gate leakage current. The present multiparametric study explicitly contrasts the performance of ion-implanted devices to otherwise identical mesa-isolated deep-submicrometer high-speed AlGaN/GaN HEMTs, in terms of transistor cutoff frequencies, small-signal model parameters, microwave noise performance, gate leakage currents, and large-signal pulsed I-V characteristics. We find that implant isolation can bring compelling advantages in terms of bandwidth, microwave noise performance, and tighter parametric distributions.

Si nanocrystals formation by a new ion implantation device

Metallic and non-metallic ion beams can be used to modify the properties of wafer surfaces if accelerated at moderate energies. We developed a new “implantation machine” able to generate ions and to accelerate them up to 80kV. The ion generation is achieved by a laser-plasma source which creates plasma in expansion. The device consists of a KrF excimer laser and a generating vacuum chamber made of stainless steel. The laser energy was 45mJ/pulse with a power density of 2.25×108W/cm2. The target was kept to positive voltage to accelerate the produced ions. The ion dose was estimated by a fast polarised Faraday cup. This machine was utilised to try synthesizing silicon nanocrystals in SiO2 matrix. Preliminary results of Si nanocrystals formation and the glancing-angle X-ray diffraction analyses are reported.

Si + implanted AlGaN/GaN HEMTs with reduced on‐resistance

Incorporation of ion implantation to AlGaN/GaN high-electron mobility transistor (HEMT) processing has been demonstrated. The source/drain regions formed using Si ion implantation into undoped AlGaN/GaN on sapphire substrate. Devices with gate length of 1 µm and source/drain distance of 5 µm were fabricated. In comparison with the conventional devices without ion-implanted source/drain structures, the ion-implanted devices showed excellent device performance. On-resistance reduced from 10.2 to 4.0 Ω·mm. Saturation drain current and maximum transconductance increase from 600 to 1100 mA/mm and from 100 to 180 mS/mm, respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Inside Vertical-Cavity Surface-Emitting Lasers: Extracting the Refractive Index From Spatial-Spectral Mode Images

We present a method to extract the internal effective refractive index of a vertical-cavity surface-emitting laser (VCSEL) from its transverse mode images. High spatial and spectral resolution mode images of an oxide-guided VCSEL were obtained using an etalon filter and an imaging spectrometer. The refractive index and the oxide radius were extracted from the field intensity distribution and the spectral wavelength of the laser modes. The procedure was repeated at two different currents and both gave a refractive index step of 0.046 plusmn 0.006 with a 14.1-mum oxide diameter. With several degrees of freedom for error available in the refractive index extraction, this method may be extended to ion-implanted, photonic crystal, and noncircular devices

Nonalloyed ohmic contacts in AlGaN/GaN HEMTs by ion implantation with reduced activation annealing temperature

This letter reports AlGaN/GaN high-electron mobility transistors with capless activation annealing of implanted Si for nonalloyed ohmic contacts. Source and drain areas were implanted with an Si dose of 1/spl times/10/sup 16/ cm/sup -2/ and were activated at /spl sim/1260/spl deg/C in a metal-organic chemical vapor deposition system in ammonia and nitrogen at atmospheric pressure. Nonalloyed ohmic contacts to ion-implanted devices showed a contact resistance of 0.96 /spl Omega//spl middot/mm to the channel. An output power density of 5 W/mm was measured at 4 GHz, with 58% power-added efficiency and a gain of 11.7 dB at a drain bias of 30 V.

Size removal on polyester fabrics by plasma source ion implantation device

Plasma treatment was evaluated as an alternative clean desizing technology in this work. As indicated by weight loss, O 2 plasma treatment efficiently removed sizing agents such as polyvintyl alcohol (PVA), polyacrylic acid esters and their mixture (MIX) on polyethylene terephthalate (PET) fabrics. SEM pictures of the plasma treated samples directly proved the disappearance of the sizing agents. XPS analysis showed apparent changes in chemical composition and functional groups of the PET surface after O 2 plasma treatment. Carbon content decreased due to the removal of sizing agents while oxygen content increased. O 2 plasma treatment also increased hydrophilic functional groups of sizing agents, which is confirmed by C 1s and O 1s deconvolution analyses. After O 2 plasma treatment, the PET fabric was subjected to conventional desizing process at different temperatures. Except for the PET fabric sized with PVA, plasma-treated fabrics showed more efficient desizing results when compared with untreated fabrics. Furthermore, the desizing effluent from the treated fabric gave lower TOC, COD and BOD values.

Performance characteristics of planar ion-implantation isolated heterojunction, near-infrared, and short-wave infrared HgCdTe devices

Two-dimensional near-infrared (NIR) and short-wave infrared (SWIR) HgCdTe arrays have been produced using planar ion-implantation isolated heterojunction (PI3H) device technology. This paper is an extension of an earlier study in which focal plane arrays (FPAs) were fabricated based on heterojunction-mesa and ion-implanted planar device structures. The PI3H device structure is pursued in order to verify whether it can encompass both the superb multilayer characteristics of heterojunction detectors as well as the planar integrity of ion-implanted devices. The PI3H devices are characterized, and R0A measurements are carried out at different temperatures and compared to those obtained from heterojunction-mesa and ion-implanted device structures. Data shows the PI3H devices to be superior to both heterojunctionmesa and ion-implanted detectors at temperatures between 130 K and 300 K. Performance characteristics of the thermoelectric (TE) cooled SWIR FPAs with 320 × 256 format, as well as NIR FPAs with 640×512 format based on the PI3H device structure are also discussed.

Integrated high-voltage modulator for plasma immersion ion implantation with an RF plasma

The present investigation focuses on further development of the plasma based high-voltage modulator for plasma immersion ion implantation devices. The modulator produces high-voltage pulses using grid controlled extraction of electrons from the plasma, which is used for the ion implantation. The operation features of the modulator in connection with a radio-frequency plasma are described. The device is applied to nitrogen ion implantations of stainless steel. The results indicate considerable hardness improvement, which confirms the practical utility of the high-voltage modulator.

A comparative study and performance characteristics of ion-implanted and heterojunction short-wave infrared HgCdTe focal-plane arrays

Short-wave infrared (SWIR) HgCdTe focal-plane arrays (FPAs) with a cutoff wavelength of 2.5 µm have been produced using both planar ion-implanted and heterojunction-mesa device structures. The two-dimensional FPAs are comprised of a 320 × 256 format with 30-µm pixel pitch and are cooled by a multistage thermo-electric (TE) cooler. Measured RoA values of the two types of device structures show similar results below about 130 K because of the performance-limiting effect of the surface passivation of the heterojunction. However, a substantial difference is seen above 130 K and up to 300 K between the two structures types, with the heterojunction-mesa p-on-n device having an order of magnitude higher RoA value than the planar ion-implanted n-on-p configuration. The difference in the RoA values is reflected in the FPA images of the two different device types, where at 200 K, both FPAs display a clear picture with the n-on-p implanted device having a somewhat lesser resolution. However, no image can be seen from the planar-implanted FPA at 300 K, whereas the heterojunction-mesa FPA still exhibits a notable image at this temperature. These differences are examined and are attributed largely to higher diffusion and generation-recombination (g-r) currents that are thought to be prevalent in the ion-implanted n-on-p device structure. Yet, baking studies carried out show the ion-implanted diodes to be slightly more robust, as experiments reveal that they tend to survive a 120°C heat treatment longer than the mesa devices, which tend to degrade after a certain period of time. The nature of n-type donors in ion-implanted diodes is discussed, and a new theory based on Te antisites is proposed to explain recent experimental findings.

Generation of high voltage pulses for PBII devices

This report is devoted to the generation of high voltage pulses which can be used in order to run plasma-based ion implantation devices. We consider the circuitry of high voltage pulse creation with different energy storages and various kinds of switches, as thyratrons in combination with pulse forming networks, hard tube switches and IGBT-switches. During the last 10 years circuits with inductive energy storage and semiconductor opening switches (SOS) have been developed. We give a detailed overview on their ability to produce pulses of different polarity and amplitudes up to hundreds of kV, current values up to 10 kA, pulse duration up to hundreds of nanoseconds and frequencies up to 10 kHz with average output power up to tens of kW. This parameters make their application as power supplies for plasma-based ion implantation devices favourable. In the last section, high voltage modulation based on the grid-controlled extraction of electrons from the plasma is described. It is shown that such kind of modulator could be integrated into a device for plasma-based ion implantation.

Characteristics of BF 3 plasma-doped gate/source/drain for 0.18-μm pMOSFETs

A BF 3 plasma doping (PLAD) process has been utilized in shallow source/drain (S/D) extension and source/drain/gate doping for high-performance 0.18-μm pMOSFETs. Low-resistance shallow junctions were obtained using a BF 3 PLAD system with a high-performance low-energy boron doping technology. The drive current and transconductance of pMOSFETs with plasma-doped S/D extensions are remarkably improved compared to those of BF 2 + ion-implanted devices, due to the low resistance of the S/D extension at the equivalent short-channel-effect characteristics. The fluorine ions in the BF 3 plasma-doped silicon are significantly less than in the BF 2 + implanted one. In the case of surface channel pMOSFETs with a BF 3 plasma-doped gate, the boron penetration and depletion in the gate poly were reduced because of the reduced fluorine incorporation into the gate poly compared to those of a conventional BF 2 ion-implanted gate. The improved characteristics of BF 3 plasma-doped gate enhance the drive current and gate oxide quality of pMOSFETs compared to conventional BF 2 +-implanted devices. No plasma damage was identified, and cobalt salicide formation is also very compatible with the plasma-doped p +/ n junction.

Microwave characterization of coplanar waveguide transmission lines fabricated by ion implantation patterning of YBa/sub 2/Cu/sub 3/O/sub 7-δ/

We report on the application of Si and Al ion-implantation patterning to the fabrication of low-loss microwave transmission lines in high-temperature superconductor (HTS) thin films. Using this technique, we have fabricated coplanar waveguide (CPW) transmission lines in YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films deposited on LaAlO/sub 3/ substrates. We have used both resonant and broadband measurements in order to characterize the performance of the resulting transmission line structures. For the broadband measurements, on-wafer calibrations were used to obtain accurate S-parameters and transmission line propagation constants up to 25 GHz. The propagation constants of the ion-implanted transmission lines do not differ significantly from those of lines patterned using conventional ion milling over the frequency range studied, with a value for the attenuation constant of approximately 0.03-0.04 dB/cm at 50 K and 10 GHz. The relatively low losses of the ion-implanted devices demonstrate the effectiveness of this method of patterning for HTS microwave device fabrication.

Uniphase operation of a GaAs resistive gate charge-coupled device

The operation of a GaAs charge-coupled device (CCD) within the UHF band is a technically challenging problem. The GaAs CCDs that were reported previously in the literature were typically operated with multiphase clocks, with the majority operated using clocks in phase quadrature. To provide the multiple UHF clock wave forms with phase correlation to a GaAs CCD demands very stable picosecond timing accuracy between the adjacent clock phases, otherwise unpredictable variations will occur in the device performance. This requirement is difficult to achieve when attempting to incorporate a GaAs CCD in a high-speed analog application, such as the 500 MHz multichannel transient digitizer application being developed at TRIUMF, because of the nonlinear behaviour of the device as a load impedance. In addition to the difficult timing requirement, there are also the electronic circuit disadvantages associated with providing a multiphase clock to a GaAs CCD. The general circuit approach used to provide a multiphase UHF clock consists of splitting or dividing a master clock signal into a set of clock signals with the desired phase properties. The disadvantages of this approach are (i) the circuits are generally narrowband, restricting the range of clock frequencies that can be used; (ii) the circuits usually consume considerable power, producing substantial heat; and (iii) the circuits are typically complex, making them costly and difficult to incorporate with a GaAs CCD. A novel uniphase clock scheme was recently developed at TRIUMF that overcomes the above technical limitations for the UHF operation of a GaAs resistive gate CCD (RGCCD). The method is unique because the static transverse electric field within the GaAs RGCCD channel required to direct the motion of charge is established using the surface potential control offered by the resistive gates, under dc-biassed conditions. This permits a simple planar device comprising four electrodes per pixel to be used instead of a more elaborate castellated or ion-implanted device. Application of a single clock signal to the GaAs RGCCD provides the required temporal transverse electric field variation to cause charge motion to occur. Charge transfer efficiencies exceeding 0.999 have been achieved with a 128 pixel GaAs resistive gate CCD using (1) a fixed frequency uniphase clock operating below 100 MHz and (2) using a triggered dual frequency uniphase clock operating at 500 MHz during the signal acquisition period and at 15.6 MHz during the signal expenditure period.

Issues in the realization of strained-layer quantum well optoelectronic devices

Ion-beam processing is the ideal complement to modern lattice-mismatched (strained-layer) heteroepitaxy for optoelectronic device fabrication. Bandstructure engineering of optoelectronic devices through the use of lattice strain is presented, and the effects of ion-beam processing on III–V strained-layer heteroepitaxial structures are summarized. Representative results from ion-implanted optoelectronic devices are presented to illustrate these principles.

A new dual gate design for low current pulse operation in 16 Mb ion-implanted bubble memory devices

A design for a dual gate which has both pseudoswap and block-replicate functions for 16-Mb ion-implanted bubble memory devices has been proposed and shown by Sato et al. (1987) to reduce the operation current-pulse amplitude. The dual gate is composed of a pair of hair-pin conductor patterns in two layers and ion-implanted tracks for the major line and the minor loop corner. The current pulses are applied through the hair-pin conductor patterns to stretch, cut, or annihilate bubbles for the operation of the dual gate. The functions of the dual gate were realized with low current pulses of less than 150 mA using 0.8- mu m-diameter bubbles. It is therefore confirmed that the dual gate with low-current operation makes the 16-Mb ion-implanted bubble memory devices more practical. >