Junction Profile Research Articles

A versatile method to profile hepatitis B virus DNA integration.

HBV DNA integration into the host genome is frequently found in HBV-associated HCC tissues and is associated with hepatocarcinogenesis. Multiple detection methods, including hybrid capture-sequencing, have identified integration sites and provided clinical implications; however, each has advantages and disadvantages concerning sensitivity, cost, and throughput. Therefore, methods that can comprehensively and cost-effectively detect integration sites with high sensitivity are required. Here, we investigated the efficiency of RAISING (Rapid Amplification of Integration Site without Interference by Genomic DNA contamination) as a simple and inexpensive method to detect viral integration by amplifying HBV-integrated fragments using virus-specific primers covering the entire HBV genome. Illumina sequencing of RAISING products from HCC-derived cell lines (PLC/PRF/5 and Hep3B cells) identified HBV-human junction sequences as well as their frequencies. The HBV-human junction profiles identified using RAISING were consistent with those determined using hybrid capture-sequencing, and the representative junctions could be validated by junction-specific nested PCR. The comparison of these detection methods revealed that RAISING-sequencing outperforms hybrid capture-sequencing in concentrating junction sequences. RAISING-sequencing was also demonstrated to determine the sites of de novo integration in HBV-infected HepG2-NTCP cells, primary human hepatocytes, liver-humanized mice, and clinical specimens. Furthermore, we made use of xenograft mice subcutaneously engrafted with PLC/PRF/5 or Hep3B cells, and HBV-human junctions determined by RAISING-sequencing were detectable in the plasma cell-free DNA using droplet digital PCR. RAISING successfully profiles HBV-human junction sequences with smaller amounts of sequencing data and at a lower cost than hybrid capture-sequencing. This method is expected to aid basic HBV integration and clinical diagnosis research.

Optimization of Nb/Al-AlO x /Nb Josephson junctions through wafer-scale anodic oxidation: a systematic characterization and performance analysis

The Nb/Al-AlO x /Nb (SIS) Josephson junction is a crucial component in many types of superconducting devices. However, it can be easily damaged during the plasma fabrication processes. Anodic oxidation is an effective method for protecting SIS junctions by oxidizing Nb and Al from the junction profile. We used a custom wafer-scale anodic oxidation system and a neutral electrolyte to study the oxidation process of Nb films and Nb-Al(-AlO x )-Nb junctions. The oxidation process was thoroughly characterized by considering factors such as morphology and electrical properties. Anodization spectroscopy revealed varying oxidation sections from the top Nb layer to the bottom layer, extending across the Al-AlO x interlayer. This indicates that a 4 nm Al layer is sufficient to cover the surface of the bottom Nb film. High-resolution transmission electron microscopy and energy dispersive spectroscopy revealed that the Nb2O5 layer produced from the oxidation of the bottom Nb layer penetrated the Al2O3 layer and migrated to the top surface as the oxidation voltage increased. The top Nb layer of the SIS junction was also subjected to oxidation, despite the presence of a protective photoresist. Following the anodic oxidation process, the entire wafer surface was coated with an insulating Nb2O5 film. This film provided protection for the SIS junctions during the subsequent microfabrication process. The fabricated junction array, consisting of 128 junctions, demonstrated uniform electrical properties benefiting from the anodic oxidation process. This systematic analysis will further the research and practical applications of SIS junctions.

Coherence Improvement of Dual-Lens Electron Holography

Abstract Coherence is one of the limiting factors in off-axis electron holography applications. This paper reports methods to improve coherence ∼18-fold by using a smaller biprism and implementing a direct electron counting camera (K-camera) in combination with an imaging filter system. We achieved 0.4 nm fringe spacing with a 1.5 μm field-of-view and ∼33% fringe contrast. The maximum coherence number, N′, of ∼1.8 × 103 was achieved, where N′ is defined as the number of fringes times fringe contrast. High spatial resolution junction profile images (nm scale) of n-channel and p-channel field-effect transistors (nFET and pFET) are demonstrated with a large field-of-view (μm scale).

Phosphorus deactivation by hydrogen on hot carrier stressed high-voltage N-channel field effect transistor CMOS device demonstrated by scanning capacitance microscopy imaging

Junction profiles of hot electron stressed high-voltage N-channel field effect transistor (NFET) devices were measured by scanning capacitance microscopy. Deactivation of phosphorous was observed on the drain side. To directly establish a link between phosphorus deactivation and hydrogen, junction profiles were measured on an unstressed NFET (N-type metal-oxide-semiconductor) device with and without H2 plasma treatment and with subsequent 400 °C annealing in helium. Phosphorus deactivation was observed in the device after H2 plasma treatment, while subsequent 400 °C annealing led to dissociation of the P–H (or H–Si–P) bond and recovery of the device junctions.

InGaAsP/InP Geiger-Mode Avalanche Photodiode Towards Sub-kHz Dark Count Rate at 20% Photon Detection Efficiency

Geiger-mode InGaAsP/InP single photon avalanche photodiode (SPAD) with a low dark count rate (DCR) of 870 Hz at a photon detection efficiency (PDE) of 20% at 1064 nm is achieved for a 40 micron diameter device at −30 °C. Extensively optimized and accurately controlled shallow/deep two-step pn junction and doping profiles are identified to play decisive roles for the performance improvement. While a state-of-the-art specific detectivity of 1.4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> cm·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> /W is realized for the optimized SPAD, a temperature coefficient of the breakdown voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">br</sub> ) of 139 mV/K, a dark current of 200 pA at 90%V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">br</sub> and a timing jitter of 280 ps at 20% PDE are also simultaneously attained. Thermal activation energies of approximate 0.5 eV are observed for both the dark current and the DCR at 253–293 K, indicates the dominant source of dark carriers is the mid-gap defect trapping states-related tunneling in the InGaAsP absorber.

Large scale graphene thermoelectric device with high power factor using gradient doping profile

The performance of a thermoelectric device fabricated with centimeter-scale monolayer graphene (active size, ∼7 × 1 cm2) was investigated in this study. The carrier type and junction profile of the active graphene layer were modulated by chemical doping. After device optimization, improvements in carrier concentration of at least 200%, which led to enhancements in power factor of at least 600%, were obtained. Under optimal performance conditions, a maximum Seebeck coefficient of ∼350 μV/K and power factor of ∼14000 μW/mK2 could be achieved under a temperature difference of 18 K. These thermoelectric parameters are at least three times higher than the best values reported for organic or other graphene-based thermoelectric devices.

Direct Laser Patterning of a 2D WSe2 Logic Circuit

AbstractCarrier doping is the basis of the modern semiconductor industry. Great efforts are put into the control of carrier doping for 2D semiconductors, especially the layered transition metal dichalcogenides. Here, the direct laser patterning of WSe2 devices via light‐induced hole doping is systematically studied. By changing the laser power, scan speed, and the number of irradiation times, different levels of hole doping can be achieved in the pristine electron‐transport‐dominated WSe2, without obvious sample thinning. Scanning transmission electron microscopy characterization reveals that the oxidation of the laser‐radiated WSe2 is the origin of the carrier doping. Photocurrent mapping shows that after the same amount of laser irradiation, with increasing thickness, the laser patterned PN junction changes from the pure lateral to the vertical‐lateral hybrid structure, accompanied by the decrease in the open circuit voltage. The vertical‐lateral hybrid PN junction can be tuned to a pure lateral one by further irradiation, showing possibilities to construct complex junction profiles. Moreover, a NOR gate circuit is demonstrated by direct patterning of p‐doped channels using laser irradiation without introducing passive layers and metal electrodes with different work functions. This method simplifies device fabrication procedures and shows a promising future in large scale logic circuit applications.

Modeling the electrochemical behavior and interfacial junction profiles of bipolar membranes at solar flux relevant operating current densities

A 1D, multi-physics model that accounts for the migration and diffusion of species, electrostatics, and chemical reactions, in particular water dissociation, at BPM interfaces was developed to study the electrochemical behavior.

Depth-dependent EBIC microscopy of radial-junction Si micropillar arrays

Recent advances in fabrication have enabled radial-junction architectures for cost-effective and high-performance optoelectronic devices. Unlike a planar PN junction, a radial-junction geometry maximizes the optical interaction in the three-dimensional (3D) structures, while effectively extracting the generated carriers via the conformal PN junction. In this paper, we report characterizations of radial PN junctions that consist of p-type Si micropillars created by deep reactive-ion etching (DRIE) and an n-type layer formed by phosphorus gas diffusion. We use electron-beam induced current (EBIC) microscopy to access the 3D junction profile from the sidewall of the pillars. Our EBIC images reveal uniform PN junctions conformally constructed on the 3D pillar array. Based on Monte-Carlo simulations and EBIC modeling, we estimate local carrier separation/collection efficiency that reflects the quality of the PN junction. We find the EBIC efficiency of the pillar array increases with the incident electron beam energy, consistent with the EBIC behaviors observed in a high-quality planar PN junction. The magnitude of the EBIC efficiency of our pillar array is about 70% at 10 kV, slightly lower than that of the planar device (≈ 81%). We suggest that this reduction could be attributed to the unpassivated pillar surface and the unintended recombination centers in the pillar cores introduced during the DRIE processes. Our results support that the depth-dependent EBIC approach is ideally suitable for evaluating PN junctions formed on micro/nanostructured semiconductors with various geometry.

Effects of junction profiles in bottom protection p-well on electrical characteristics of 1.2 kV SiC trench-gate MOSFETs

Effects of junction profiles in bottom protection p-well (BPW) on electrical characteristics of 1.2 kV SiC trench-gate MOSFETs were investigated using simulation methods. Breakdown mechanisms of BPW in the device were also elucidated by energy-band diagram and electric-field distribution across trench-gate. Monte Carlo Al-implantation simulation on the trench structure for BPW formation was carried out with variations in peak depth (DBPW), concentration (NBPW), and thickness of SiO2 spacer (Tspacer) on trench sidewall. The SiC trench-gate MOSFETs with deep DBPW, high NBPW, and thin Tspacer are suitable for high drain voltage due to a shielded trench gate by BPW. However, specific on-resistance (Ron,sp) increased because of laterally penetrated Al into p-base and accumulation regions during ion implantation for BPW formation. In case of shallow DBPW, low NBPW, and thick Tspacer, however, the gate oxide at trench bottom corner is considerably vulnerable to the dielectric breakdown due to fully depleted BPW near trench bottom corner and electric-field crowding at gate oxide.

Structural Modification of Doped Tunnel Field Effect Transistor for Enhanced Conduction Current and Lower Subthreshold Swing

The material solubility in the source region and abrupt source/channel junction profile are the major concern which is responsible for the improvement of the electrical characteristics of conventional physical doped tunnel field effect transistor (PD-TFET). For this, an additional negatively polarised electrode is mounted in P+ (source) – N (channel) – N+ (drain) structure over the source region to overcome material solubility. This improves the electrical characteristics of the device. Along with this, we have implanted a low workfunction metal layer (ML) in the oxide layer under the gate electrode for creating more abruptness at the junction to improve the subthreshold swing (SS) of the device. Thus, the proposed concept improves the DC/RF performance of the doped TFET device. Further to this, the optimization of metal layer workfunction and misalignment of metal layer in TFET have been performed to get optimum device characteristics. In addition to this, for the suppression of ambipolar behaviour, gate electrode is shorted from the drain side. Due to short length of gate electrode tunneling barrier width at the drain/channel junction increases, hence the tunneling probability decreases which reduces the ambipolar current to parasitic current. Shortening of gate electrode also improves the RF performance.

Boron Implanted Junction with In Situ Oxide Passivation and Application to p‐PERT Bifacial Silicon Solar Cell

Boron junction and its passivation is an active topic in photovoltaic research due to its importance to passivated emitter and rear totally‐diffused (PERT) bifacial Si solar cell. In this paper, a systematic study on boron‐implanted junction, its passivation and ohmic contact formation, as well as application to p‐PERT bifacial cells has been presented. More specifically, the impact of junction profile and surface passivation on boron junction quality, which can be influenced by implantation and in situ oxidation anneal parameters is studied. Good‐quality boron emitter and metal/p+‐Si ohmic contact are achieved, as demonstrated by emitter saturation current of 5–30 fA cm−2 and specific contact resistance of 3–6 mΩ cm−1. A roadmap for a p‐PERT bifacial cell using fully ion implanted (boron and phosphorus) technology, based on which p‐PERT bifacial cells demonstrats front side efficiency of 20.6% (open circuit voltage of 658 mV), rear side efficiency of ≈17% and bifaciality factor of 0.82–0.87 is also presented. Effective cell efficiency of ≈22% is achieved with a Halm IV‐tester with white transporting belts that enhance reflection about 10% from the cell rear.

Ultra-Thin GaAs Double-Junction Solar Cell With Carbon-Doped Emitter

We address the challenge in depositing ultra-thin GaAs cells (<200 nm) using a more scalable process (metal–organic chemical vapor deposition). We present results for a GaAs/GaAs double-junction solar cell with a 110-nm-thick top cell. Current, voltage, fill factor, and efficiency of this architecture are improved by replacing the zinc doping in the emitter of the top cell with carbon doping. We find that the carbon doping results in a well-defined active junction profile that agrees well with the secondary ion mass spectroscopy measurement. Additionally, we find that the carbon doping coincides with the incorporation of indium in the emitter. We postulate that the incorporation of indium relieves stress in the material, which results in a smoother morphology of the GaAs film. Finally, we show the efficiency achieved with the carbon-doping process is 19.2% for the GaAs/GaAs dual junction cell. The open circuit voltage is 1.087 V for the ultra-thin (110 nm) GaAs top cell and 2.08 V for the dual junction cell.

Advantages of Faceted P-Raised Source/Drain in Fully Depleted Silicon on Insulator Technology

Recently, a 22nm fully depleted gate-first SOI technology (FDSOI) has shown significant promise as a low-cost alternative to FinFETs with devices that are tunable between low-leakage and high-performance regimes. [1] The 22nm FDSOI PFET utilizes a SiGe channel with epitaxial grown raised source/drain (RSD) to define the junction profile, strain the channel, and facilitate contact formation. The pRSD epitaxial growth is typically a two-layer process with a main layer of SiGe:B followed by a capping layer of Si. Because the RSD epitaxy grows along the spacer dielectric, it results in a parasitic capacitance to the Gate electrode which then contributes to the total MOSFET capacitance and degrades AC device performance. Since the thickness of the main layer as well as the cap layer has a strong influence on this parasitic capacitance (Cgd), the RSD thickness should, in theory, be kept as low as possible. This is necessary to achieve the maximum AC and RF device performance. However, decreasing the RSD thickness below a certain level has the undesirable effect of DC performance drop. Therefore, another approach is needed to decrease Cgd further without degrading the drive current. In this paper we present one of the strongest methods to increase FDSOI technology AC/RF device performance, namely faceted raised source/drain epitaxial growth. Faceted pRSD epitaxy effectively decouples the RSD height and Cgd, lowering the parasitic capacitance not by reduced total RSD height, but rather by eliminating the shared wall between the Gate and the RSD. This simple approach has two desirable outcomes: 1) low Cgd & AC performance gain, and 2) low electrical variability via suppressing the influence of RSD height variation. The primary electrical response from faceted pRSD is the lowering of Cgd up to 25% at matched DC performance at zero gate bias; and this resulted in approximately 5% ring oscillator performance and ca. 20GHz RF p-Ft improvement. Other advantages of faceted pRSD are the selectivity in epitaxial growth and electrical variability. As mentioned previously, in a typical FDX device, RSD height needs to be controlled very tightly to achieve low device variability in DC transistor parameters (Ieff, Vtsat, Ioff) and Cgd. With faceted pRSD, however, this “shared wall” between Gate and RSD is liminated. We observed that the Cgd did not respond over a range of +/- 13% in main layer thickness, which led to a tight distribution of transistor parameters. Put another way, with faceted RSD, the primary need of a tight control over the pRSD thickness is eliminated.

Effect of hot carrier stress on device junctions measured by electron holography and scanning capacitance microscopy

The effect of hot carrier injection on the FET's junction properties has been investigated for CMOS NFET devices. Junction profiles and carrier concentration of stressed and unstressed devices are measured and compared by dual lens electron holography and scanning capacitance microscopy, respectively. The measurements reveal that the width of the junction on the drain side of the device that undergoes hot carrier stressing decreases, indicating a reduction in active carrier concentration. These results are consistent with the hypothesis of phosphorous dopant passivation by the hot carrier induced release of hydrogen into the drain side extension region.

The influence of limbal and scleral shape on scleral lens design.

To summarize the research findings on the ocular surface profile, to provide a definition and a classification of the corneoscleral shape, and to offer guidelines in selecting scleral lens design. The definition of rotational symmetry and rotational asymmetry was inquired and PubMed searches were conducted. The better understanding of the scleral contact lens comportment on the eye and the introduction of new diagnostic instruments to measure the anterior ocular surface have led to improve comprehension of corneoscleral contour formulating new scleral lens designs. The scleral lens landing zone is influenced by corneoscleral profile which may be rotationally symmetric and rotationally asymmetric. Corneal sagittal height, limbal shape, corneoscleral junction profile, corneal, limbal, and conjunctival angles, and scleral shape should be taken in consideration to prevent and manage fitting problems, such as air bubble formation, midday fogging, localized blanching, impingement, conjunctival prolapse, lens decentration, lens flexure, and to increase comfort, wearing time, overall satisfaction, and visual quality. Corneoscleral shape may be considered rotationally symmetric including spherical, aspherical and toric profiles, and rotationally asymmetric including regular and irregular quadrants profiles. Each ocular surface contour requires a different landing zone design for an optimal fitting, vaulting properly over the cornea and limbus, and ideal alignment on the sclera. Further studies are still necessary to clarify many aspects of scleral lenses which are little known yet.

Scanning Spreading Resistance Microscopy for Doping Profile in Saddle-Fin Devices

Scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) are used to investigate the doping profile of saddle-fin (S-fin) devices in a 30-nm dynamic-random-access-memory (DRAM) technology. Due to the limited resolution of SCM, SCM cannot provide a clear doping profile of an S-fin array device. In the meantime, SSRM and focused ion beam milling during sample preparation provide an opportunity to obtain a 2-D and scanning line doping profile. The common-source region between two adjacent buried word lines is treated with an additional phosphorus (P) implantation with energy and dosage modification to have a doping profile modification in the array devices of DRAM product. With condition of the medium energy and high dosage in this additional P implantation, the row hammer effect of 30-nm DRAM could be minimized by the localized shielding effect from the electric field by a depletion effect. The junction profile of the additional P implantation is about 10 nm deeper than that of the control sample, as verified by SSRM and technology computer-aided design simulation. The experimental results of the doping profile can be used to support a mechanism of improvement of row hammer. The SSRM methodology proposed in this study could be used to optimize the doping profiles in DRAMs for future scaling technology.

Optical and electrical properties of nanostructured implanted silicon n+-p junction passivated by atomic layer deposited Al2O3

This paper investigates the optical and electrical properties of nanostructured implanted silicon junctions passivated by Al2O3 layers. A two-step ion implantation method has been developed to fabricate the nanostructured n+-p junctions with theoretical support of two dimensional Monte Carlo simulations to predict and optimize the junction profile. Dense and uniform arrays of silicon nanopillars and nanocones were formed by combining nanosphere lithography and dry etching, exhibiting a low reflectance in a broad spectrum from 300 to 800nm. A conformal Al2O3 layer was deposited on the array by using thermal atomic layer deposition (ALD) to achieve chemical passivation effect. External quantum efficiency and power conversion efficiency of the junctions were measured versus nanostructuration and Al2O3 passivation. The results showed that significant enhancement of efficiency can be achieved on the passivated nanopillar-based junctions.

Optimization of the Junction Profile Through Control of the Doping Heat Profile for Silicon Solar Cell Applications

Optimization of the Junction Profile Through Control of the Doping Heat Profile for Silicon Solar Cell Applications

The role of gap junctions in inflammatory and neoplastic disorders (Review).

Gap junctions are intercellular channels made of connexin proteins, mediating both electrical and biochemical signals between cells. The ability of gap junction proteins to regulate immune responses, cell proliferation, migration, apoptosis and carcinogenesis makes them attractive therapeutic targets for treating inflammatory and neoplastic disorders in different organ systems. Alterations in gap junction profile and expression levels are observed in hyperproliferative skin disorders, lymphatic vessel diseases, inflammatory lung diseases, liver injury and neoplastic disorders. It is now recognized that the therapeutic effects mediated by traditional pharmacological agents are dependent upon gap junction communication and may even act by influencing gap junction expression or function. Novel strategies for modulating the function or expression of connexins, such as the use of synthetic mimetic peptides and siRNA technology are considered.