The generation of misfit dislocations has been investigated on epitaxial silicon wafers with boron-doped substrates, as a function of the film thickness and the misfit resulting from the difference in lattice parameters between the film and the substrate. Critical values of the film thickness hc and of the misfit fc required to form misfit dislocations were found to be hc=2.4–-2.9 μ for the interfacial misfit of 0.019% and fc=0.003–0.006% for relatively large film thickness, where the interfacial energy approaches that of infinitely thick film. These results were analyzed in terms of van der Merwe's theory and a good agreement was found between the experiment and the theory. The density of misfit dislocations was observed to increase with the interfacial misfit or with the film thickness. The relation between bending of the specimens associated with the misfit and the film thickness was studied. Some properties of misfit dislocations are described.

Grown-in microdefects of a slowly grown Czochralski (CZ) silicon crystal were studied by short wavelength synchrotron radiation topography and successfully visualized. It was shown that the microdefects had spherical strain fields, by comparing the defect images in the two topographs taken with the Bragg reflections perpendicular and parallel to the growth direction. The radial distributions of the microdefect size and density were measured from the defect images in the topographs. The misfit volume of the microdefects was approximately 1 ×10-12 cm3 at the central axis region of the crystal ingot, and decreased monotonically toward the peripheral region of the crystal. The density of the microdefects was approximately 300/cm3 at the center of the crystal, increased toward the periphery and then decreased rapidly to almost zero in the very peripheral region approximately 7 mm from the surface of the crystal ingot. These radial distributions are discussed in connection with the self-interstitial atoms of silicon crystals.

BackgroundA better understanding of the tumor immune microenvironment (TIME) will facilitate the development of prognostic biomarkers and more effective therapeutic strategies in patients with lung cancer. However, little has been reported on the comprehensive evaluation of complex interactions among cancer cells, immune cells, and local immunosuppressive elements in the TIME.MethodsWhole-exome sequencing and RNA sequencing were carried out on 113 lung cancers. We performed single sample gene set enrichment analysis on TIME-related gene sets to develop a new scoring system (TIME score), consisting of T-score (tumor proliferation), I-score (antitumor immunity) and S-score (immunosuppression). Lung cancers were classified according to a combination of high or low T-score, I-score, and S-scores (eight groups; G1-8). Clinical and genomic features, and immune landscape were investigated among eight groups. The external data sets of 990 lung cancers from The Cancer Genome Atlas and 76 melanomas treated with immune checkpoint inhibitors (ICI) were utilized to evaluate TIME scoring and explore prognostic and predictive accuracy.ResultsThe representative histological type including adenocarcinoma and squamous cell carcinoma, and driver mutations such as epidermal growth factor receptor and TP53 mutations were different according to the T-score. The numbers of somatic mutations and predicted neoantigens were higher in Thi (G5-8) than Tlo (G1-4) tumors. Immune selection pressure against neoantigen expression occurred only in Thi and was dampened in Thi/Ilo (G5-6), possibly due to a reduced number of T cells with a high proportion of tumor specific but exhausted cells. Thi/Ilo/Shi (G5) displayed the lowest immune responses by additional immune suppressive mechanisms. The T-score, I-score and S-scores were independent prognostic factors, with survival curves well separated into eight groups with G5 displaying the worst overall survival, while the opposite group Tlo/Ihi/Slo (G4) had the best prognosis. Several oncogenic signaling pathways influenced on T-score and I-scores but not S-score, and PI3K pathway alteration correlated with poor prognosis in accordance with higher T-score and lower I-score. Moreover, the TIME score predicted the efficacy of ICI in patients with melanoma.ConclusionThe TIME score capturing complex interactions among tumor proliferation, antitumor immunity and immunosuppression could be useful for prognostic predictions or selection of treatment strategies in patients with lung cancer.

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A method of measuring the local variations in the spacing and the orientation of a lattice plane in a single crystal is reported. The angular positions of diffraction peak at each point of the specimen are measured at four incident azimuths making 90° to each other by a double-crystal spectrometer. This method is applied to two specimens of silicon single crystals doped with arsenic and containing oxygen respectively. The growth striations observed in the two specimens are for the most part due to the variation in lattice spacing. The intensity contrast extended in the long range is due to misorientation.