Invited; Solid-phase crystallization of hydrogen-doped indium oxide for low temperature processed TFTs

An amorphous In–Ga–Zn–O (IGZO) has attracted particular attention for thin-film transistor (TFT) applications owing to its high field effect mobility (μFE) of more than 10 cm2V−1s−1, steep subthreshold swing, extremely low leakage current, large-area uniformity, and good bias stress stability. Although the μFE of an IGZO TFT is over one order of magnitude higher than that of an amorphous Si TFT, further improvement of the μFE of oxide TFTs is required to expand their range of applications for both the displays and LSIs. An indium oxide (InOx) is known as a potential material for enhancing the μFE of oxide TFTs. However, undoped InOx exhibit a high background carrier density of over 1020 cm-3, making them unsuitable for a channel material of the TFTs. Please click Download on the upper right corner to see the full abstract

Carrier transport and bias stress stability of IGZO TFT with heterojunction channel

An InGaZnOx (IGZO) thin-film transistor (TFT) has been received considerable attention for use in next-generation displays owing to their excellent electrical properties. Although a field effect mobility (mFE) of the IGZO TFT (10~15 cm2V–1s–1) is over ten times larger than that of an amorphous silicon TFT, further enhancement of the mFE is desired to expand their applications. Several approaches have been proposed to improve the mFE of oxide TFT. Among them, it is known in the IGZO material system that an increase of In content is effective to enhance the mFE of the IGZO TFT since a conduction band of the IGZO is mainly composed of an In 5s orbitals. However, high In composition leads to an increase carrier concentration (oxygen vacancy) in the film, result in a degradation of TFT properties such as negative shift of threshold voltage and hump in transfer characteristics. Please click Additional Files below to see the full abstract

Low-temperature processed InGaZnO MES-FET for flexible device applications

Amorphous oxide semiconductor (AOSs) of an In-Ga-Zn-O (IGZO)1) is expected to be used as a channel material for thin-film transistors (TFTs) because the IGZO TFTs exhibit field-effect motility (μFE) of over 10 cm2/Vs and good uniformity even fabricate at room temperature. The oxide TFTs with metal-insulator-semiconductor (MIS) structure have been employed widely; however, maximum processing temperature of 300-400 °C is required to guarantee the performance and reliability of the TFTs. In contrast, metal-semiconductor field effect transistor (MES-FET) has several advantages especially for flexible devices since a Schottky gate can be formed at low temperature with AOSs. There are a few reports of AOSs based MES-FET2, 3); however, it has remained an issue to form stable and good Schottky contact on the AOSs. We reported the top-gated MES-FET with the IGZO channel, which was deposited by mist chemical vapour deposition at 350 °C, and sputtered silver oxide (AgOx) Schottky gate4). The μFE of 3.2 cm2/Vs and subthreshold swing (SS) of 356 mV/decade were achieved. However, a maximum processing temperature of the MES-FET was 350 °C, which was not suitable for flexible device applications. In this presentation, the IGZO MES-FET with AgOx Schottky gate was fabricated at a maximum processing temperature of 150 °C. We investigated the influences of deposition conditions and post-deposition annealing on electrical properties of the low-temperature processed IGZO MES-FET. Figure 1 shows a cross sectional view of the IGZO MES-FET. First, a 100 nm-thick IGZO film was deposited on glass substrate by DC magnetron sputtering without intentional substrate heating from InGaZnO (In:Ga:Zn=1:1:1 mol.%) target. Deposition pressure was kept at 1.0 Pa, while the O2 gas ratio [R(O2)=O2/(Ar+O2)] was varied at 0.66, 0.80, and 1.00%. The IGZO film was patterned into an active channel by conventional photolithography and wet etching. The IGZO channel was then annealed at 100 or 150 ºC for 1h in ambient air. A 120 nm-thick AgOx was deposited by DC reactive sputtering, and Au was deposited on the AgOx by thermal evaporation. The AgOx/Au stacked Schottky gate was patterned by lift-off. Finally, Mo source and drain electrodes was formed by lift-off. Channel width/length of the MES-FET was 100/10 μm. Figure 2 shows the (a) forward and reverse currents of the IGZO/AgOx Schottky diode and (b) on and off current of the IGZO MES-FET, as a function of the Hall carrier concentration (NHall) in the IGZO channel. The diode properties were well correlated with the NHall; however, on-current of the MES-FET depended on not only NHall but also the R[O2] of the IGZO deposition. Carrier transport mechanism of the IGZO MES-FET and control methods of electrical properties will be discussed at the conference. Please click Additional Files below to see the full abstract

Association between Lactobacillus species and bacterial vaginosis-related bacteria, and bacterial vaginosis scores in pregnant Japanese women

<p>Abstract</p> <p>Background</p> <p>Bacterial vaginosis (BV), the etiology of which is still uncertain, increases the risk of preterm birth. Recent PCR-based studies suggested that BV is associated with complex vaginal bacterial communities, including many newly recognized bacterial species in non-pregnant women.</p> <p>Methods</p> <p>To examine whether these bacteria are also involved in BV in pregnant Japanese women, vaginal fluid samples were taken from 132 women, classified as normal (n = 98), intermediate (n = 21), or BV (n = 13) using the Nugent gram stain criteria, and studied. DNA extracted from these samples was analyzed for bacterial sequences of any <it>Lactobacillus</it>, four <it>Lactobacillus </it>species, and four BV-related bacteria by PCR with primers for 16S ribosomal DNA including a universal <it>Lactobacillus </it>primer, <it>Lactobacillus </it>species-specific primers for <it>L. crispatus</it>, <it>L. jensenii</it>, <it>L. gasseri</it>, and <it>L. iners</it>, and BV-related bacterium-specific primers for BVAB2, <it>Megasphaera</it>, <it>Leptotrichia</it>, and <it>Eggerthella</it>-like bacterium.</p> <p>Results</p> <p>The prevalences of <it>L. crispatus</it>, <it>L. jensenii</it>, and <it>L. gasseri </it>were significantly higher, while those of BVAB2, <it>Megasphaera</it>, <it>Leptotrichia</it>, and <it>Eggerthella</it>-like bacterium were significantly lower in the normal group than in the BV group. Unlike other <it>Lactobacillus </it>species, the prevalence of <it>L. iners </it>did not differ between the three groups and women with <it>L. iners </it>were significantly more likely to have BVAB2, <it>Megasphaera, Leptotrichia</it>, and <it>Eggerthella</it>-like bacterium. Linear regression analysis revealed associations of BVAB2 and <it>Megasphaera </it>with Nugent score, and multivariate regression analyses suggested a close relationship between <it>Eggerthella</it>-like bacterium and BV.</p> <p>Conclusion</p> <p>The BV-related bacteria, including BVAB2, <it>Megasphaera</it>, <it>Leptotrichia</it>, and <it>Eggerthella</it>-like bacterium, are common in the vagina of pregnant Japanese women with BV. The presence of <it>L. iners </it>may be correlated with vaginal colonization by these BV-related bacteria.</p

CNVs in Three Psychiatric Disorders

BACKGROUND: We aimed to determine the similarities and differences in the roles of genic and regulatory copy number variations (CNVs) in bipolar disorder (BD), schizophrenia (SCZ), and autism spectrum disorder (ASD). METHODS: Based on high-resolution CNV data from 8708 Japanese samples, we performed to our knowledge the largest cross-disorder analysis of genic and regulatory CNVs in BD, SCZ, and ASD. RESULTS: In genic CNVs, we found an increased burden of smaller (500 kb) exonic CNVs in SCZ/ASD. Pathogenic CNVs linked to neurodevelopmental disorders were significantly associated with the risk for each disorder, but BD and SCZ/ASD differed in terms of the effect size (smaller in BD) and subtype distribution of CNVs linked to neurodevelopmental disorders. We identified 3 synaptic genes (DLG2, PCDH15, and ASTN2) as risk factors for BD. Whereas gene set analysis showed that BD-associated pathways were restricted to chromatin biology, SCZ and ASD involved more extensive and similar pathways. Nevertheless, a correlation analysis of gene set results indicated weak but significant pathway similarities between BD and SCZ or ASD (r = 0.25–0.31). In SCZ and ASD, but not BD, CNVs were significantly enriched in enhancers and promoters in brain tissue. CONCLUSIONS: BD and SCZ/ASD differ in terms of CNV burden, characteristics of CNVs linked to neurodevelopmental disorders, and regulatory CNVs. On the other hand, they have shared molecular mechanisms, including chromatin biology. The BD risk genes identified here could provide insight into the pathogenesis of BD

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Exploring the photoleakage current and photoinduced negative bias instability in amorphous InGaZnO thin-film transistors with various active layer thicknesses

The photoleakage current and the negative bias and illumination stress (NBIS)-induced instability in amorphous InGaZnO thin-film transistors (a-IGZO TFTs) with various active layer thicknesses (TIGZO) were investigated. The photoleakage current was found to gradually increase in a-IGZO TFTs irrespective of the TIGZO when the photon energy of visible light irradiation exceeded ≈2.7 eV. Furthermore, the influence of the TIGZO on NBIS-induced instability in a-IGZO TFTs was explored by the combination of current–voltage measurements in double-sweeping VGS mode and capacitance–voltage measurements. The NBIS-induced hysteresis was quantitatively analyzed using a positive gate pulse mode. When the TIGZO was close to the Debye length, the trapped electrons at the etch-stopper/IGZO interface, the trapped holes at the IGZO/gate insulator interface, and the generation of donor-like states in an a-IGZO layer were especially prominent during NBIS