Semiconductor nanowires (NWs) have been extensively investigated and discussed in various fields due to their unique physical properties. In this paper, we successfully produce SiGe NWs biosensor by VLSI technology. We propose the dual plasma technology with CF4 plasma pre-treatment and N2 plasma post-treatment for repairs of defects as well as optimization of SiGe NWs biosensor. The results indicate that sensitivity (S) of the biosensor with dual plasma technology has significantly improved at least 32.8%, suitable for producing industrial SiGe NWs biosensor in the future.

Si1-xGex nanowire biosensors are attractive for their high sensitivity due to the large surface-to-volume ratio, high carrier mobility, and silicon compatibility. In this work, we study the effect of the thickness of the low-temperature Si (LT-Si) buffer layer on an insulator on the sensitivity of oxidized Si1-xGex nanowire samples with different Ge contents by increasing the Si buffer thickness from 20 to 60 nm. 3-Aminopropyltrimethoxy-silane (APTMS) was used as a biochemical reagent. It was demonstrated that, with the proper Ge content and LT-Si buffer thickness, the sensitivity of the Si1-xGex nanowire is high and it can be further improved by Si1-xGex oxidation. This can be attributed to the reduction of the diameter to the nanometer order, which gives rise to an increased surface-to-volume ratio and further enhances the sensitivity of the biosensor. (C) 2015 The Japan Society of Applied Physics

Nanowires are extensively used to fabricate highly sensitive electrical sensors for detection of biological and chemical species. The hole mobility can be promoted by the increasing Ge fraction in SiGe, achieved by the oxidation-induced Ge condensation. However, oxidation increases the number of surface states, which brings the nonnegligible contribution in mobility degradation. In this work, 3-aminopropyltrimethoxysilane (APTMS) was used as a biochemical reagent to modify the surface of SiGe nanowires, then bonding to bio-linker, bis (3-sulfo-N-hydroxysuccinimide ester) sodium salt (BS3). Various methods have been proposed for increasing sensitivity of boron-doped SiGe nanowires, such as capping layer, surface treatment, and annealing temperature.

The improvements to electrical properties of SiGe nanowires by surface plasma treatment were investigated. Various durations of pre-oxidation with fluorine; ambients for post-nitridation plasma treatment, and annealing temperature after plasma treatment, 800-950 degrees C, were applied. Pre-oxidation treatment using fluorine plasma; improved the conductance of SiGe nanowires because the Si-F binding energy created a more stable interface state than bare nanowire on the surface of SiGe. N-2 plasma incorporated more N than does in NH3 plasma, and NH3 has the drawback of introducing electron traps, causing Si-H bonds to break in the subsequent annealing process. Since the reparation of surface defects by plasma treatment is valid, the high post-annealing temperature to reduce defect by re-crystallizing can be reduced. Hence, Ge diffusion at low post-annealing temperature did not reduce the high concentration of Ge at the SiGe nanowire surfaces. (C) 2013 Elsevier B.V. All rights reserved.

Nanowires are widely used as highly sensitive sensors for electrical detection of biological and chemical species. Modifying the band structure of strained-Si metal-oxide-semiconductor field-effect transistors by applying the in-plane tensile strain reportedly improves electron and hole mobility. The oxidation-induced Ge condensation increases the Ge fraction in a SiGe-on-insulator (SGOI) and substantially increases hole mobility. However, oxidation increases the number of surface states, resulting in hole mobility degradation. In this work, 3-aminopropyltrimethoxysilane (APTMS) was used as a biochemical reagent. The hydroxyl molecule on the oxide surface was replaced by the methoxy groups of the APTMS molecule. We proposed a surface plasma treatment to improve the electrical properties of SiGe nanowires. Fluorine plasma treatment can result in enhanced rates of thermal oxidation and speed up the formation of a self-passivation oxide layer. Like a capping oxide layer, the self-passivation oxide layer reduces the rate of follow-up oxidation. Preoxidation treatment also improved the sensitivity of SiGe nanowires because the Si-F binding was held at a more stable interface state compared to bare nanowire on the SiGe surface. Additionally, the sensitivity can be further improved by either the N2 plasma posttreatment or the low-temperature postannealing due to the suppression of outdiffusion of Ge and F atoms from the SiGe nanowire surface.

The Ge condensation method is effective in increasing the Ge fraction of Ge in SGOI. Previous studies by the authors confirmed a correlation between the Ge fraction and the sensitivity of the SiGe nano-wire sensor. To understand how Ge condensation on an SGOI nano-wire sensor helps to optimize oxidation conditions and sensitivity, the effect of oxidizing gas and the SiGe/α-Si stacked structure on the movement of Ge is investigated. The analytical results reveal that the sensitivity of SiGe nano-wires can be optimized by stacking an Si1-xGex layer that contains 14% Ge on a 200 Å-thick α-Si layer and treating the stack with O2 gas diluted by 13% N2 for 3 min.

Ge condensation offers an attractive way to increase Ge the fraction of Ge in SGOI. From authors' previous investigations, increasing the fraction of Ge increases the sensitivity of the SiGe nanowire sensor. To understand how Ge condensation on an SGOI nanowire sensor helps to optimize the conditions of oxidation and improve the sensitivity of the sensor, the effect of oxidation gas and SiGe/α-Si stacked structure on the movement of Ge is examined. The results reveals that SiGe nanowire has a maximum sensitivity when it includes a 14% Ge containing Si1-xGex layer that is stacked on a 200 Å-thick α-Si layer and is treated for 3 min with O2 gas to which is added 13% N2 gas.

Increasing the fraction of Ge in SiGe-on-Insulator (SGOI) using Ge condensation by oxidation significantly increases hole mobility. This effect can be exploited to improve the sensitivity of SGOI nanowire. However, our previous studies found that the sensitivity of an SGOI nanowire is degraded as the Ge fraction increases over 20%, because of the surface state of SiGe is unstable when the Ge fraction is high. In this work, a top surface passtivation SiO2 layer was deposited on an Si0.8Ge0.2 nanowire and successfully improve its sensitivity around 1.3 times that of the nanowire sample without top a passivation layer.

Increasing the fraction of Ge in SiGe-on-Insulator (SGOI) using Ge condensation by oxidation significantly increases hole mobility. This effect can be exploited to improve the sensitivity of SGOI nanowire. However, our previous studies found that the sensitivity of an SGOI nanowire is degraded as the Ge fraction increases over 20%, because of the surface state of SiGe is unstable when the Ge fraction is high. In this work, a top surface passtivation SiO2 layer was deposited on an Si0.8Ge0.2 nanowire and successfully improve its sensitivity around 2.5 times that of the nanowire sample without top a passivation layer.

The increase of surface to volume ratio results in the enhancement of the sensitivity of the nanowires. Our previous studies have shown that the higher Ge fraction of Si1-xGex nano-wire improves the sensitivity of the nanowire biosensor as a result of carrier mobility enhancement in strain-Si. Increasing the fraction of Ge in SiGe-on-Insulator (SGOI) using Ge condensation by oxidation has obtained a significant enhancement in hole mobility, further improving the sensitivity of SGOI nanowire. However, the sensitivity of SGOI nanowire was degraded for exceeding a Ge fraction of 20% (i.e., high Ge fraction), resulting from the unstable surface state. In this work, a top surface passivation SiO2 layer was deposited on Si0.8Ge0.2 nanowire and the sensitivity was about 1.3 times greater than nanowire sample without the top passivation layer.

Increasing the fraction of Ge in SiGe-on-Insulator (SGOI) using Ge condensation by oxidation significantly increases hole mobility. This effect can be exploited to improve the sensitivity of SGOI nanowire. However, our previous studies found that the sensitivity of an SGOI nanowire is degraded as the Ge fraction increases over 20%, because of the surface state of SiGe is unstable when the Ge fraction is high. In this work, a top surface passtivation SiO2 layer was deposited on an Si0.8Ge0.2 nanowire and successfully improve its sensitivity around 1.3 times that of the nanowire sample without top a passivation layer.

Because of the large surface-to-volume ratio of nano-structure, the silicon nanowires (SiNWs) provide a high sensitivity for highly sensitive detection of biological and chemical species. Moreover, the SiGe-on-Insulator (SGOI) by Ge-condensation process can enhance the mobility of hole carrier and then improve the nanowires's conductance. In this study, we discuss SiGe nanowire structural effect by changing Si/SiGe stacked ratio and oxidation effect in different annealing ambient. The optimized Si/SiGe stacked structure with suitable oxidation process has more twice enhancement of sensitivity compared to conventional SiNWs biosensor.

Nanowire is widely used in biological sensor because it has the high surface-to-volume ratio. Germanium (Ge) would be beneficial to enhance the sensitivity of silicon nanowire for bio-sensor. In this study, we have successfully fabricated the SiGe on Insulator (SGOI) nanowires with different annealing temperature by side-wall spacer technique, respectively. The 3-amino-propyltrime-thoxy-silane (APTS) is used to modify the surface, which can connect the bio-linker. Nanowire is considered as a resistance, and the change of conductance (Delta G) and sensitivity (S) of different samples corresponding to APTS treatment were investigated. As annealing temperature was elevated from 800 to 950 degrees C, the SiGe nanowire exhibited increasing sensitivity in the chemical detection. However, it was noted that degradation of sensitivity was observed as the annealing temperature increases up to 1000 degrees C. This behavior may be associated with the reduction of the Ge concentration at the surface of SiGe nanowire due to high-temperature diffusion of Ge in Si. So, temperature is a key parameter in the annealing process producing two effects: repairs of defects and Ge diffusion. There would be an optimal annealing temperature between 900 and 1000 degrees C.

Abstract not Available.

Ge condensation has been reported to improve the hole mobility of the SiGe-on-insulator (SGOI). Our previous studies have shown that the higher Ge fraction of Si1-xGex nano-wire exhibits higher sensitivity. In this work, we investigated the effect of different oxidation recipe to provide information on the sensitivity of SiGe nano-wire. The 3-amino-propyltrime-thoxy-silane (APTMS) is used to modify the nano-wire's surface potential. Induced sensitivity characteristics of the samples were preformed to estimate the improvement effect. The mixed N2/O2 oxidation process with optimization ratio can be an effective technology to improve the sensitivity of SGOI nano-wires.

Reducing the width of a nano-wire increases its surface to volume ratio, increasing the sensitivity of its conductivity to charges on its surface. Our previous studies have shown that increasing the Ge fraction in Si1-xGex nano-wires improves their sensitivity as bio-sensing. In this work, an α-Si/SiGe core/shell nano-wire is successfully fabricated using side-wall spacer method. The maximum sensitivity of a nano-wire bio-sensor with an optimizedα-Si/SiGe thickness ratio is investigated.

Historically, development of medical imaging applications has focused on solving technical issues for small numbers of expert users. However, their use is now more mainstream and users are no longer willing to tolerate poor performance and usability. In this study we illustrate the application of user centred design methods in a medical imaging applications development company by using a usability comparative study of different regions of interest (ROI) tools. A use case analysis was used to judge usability efficiency and effectiveness of different ROI tools; and a user observation was also carried out which measured the accuracy achieved by these tools. We have found that useful results can be obtained by using these methods. We also generated some concrete suggestions that could be incorporated into future product development.

In this paper we describe a system for storing and retrieving digital images from personal collections. The images can either be manually annotated with a set of keywords chosen by the owner of the collection, or keywords can be automatically inferred from the time and location stamps associated with the image and the Geographic Names Data Base gazetteer. User queries are matched against the image annotations using the Cosine Similarity Measure, and the best matching images are displayed. To enable browsing of the image collection, the images are clustered according to time and location, the two main factors of episodic memory. User studies were conducted to compare the two annotation systems with time and location clustering alone, using searching time, recall and precision, and user satisfaction as criteria for success. Our results show that matching based on automatically assigned keywords was significantly better than time and location-based browsing alone, and performed at least as well as matching against user-assigned annotations.