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We demonstrated that silicon vacancy (VSi) can be created in SiC pn junction diode by proton beam writing (PBW) without degradation of the diode performance. The VSi showed the same specific emission for both optically and electrically excitation, which suggests that electrically controllable VSi was created. In addition, optically detected magnetic resonance (ODMR) signal was successfully detected from optically excited VSi at room temperature. This result suggests that VSi introduced into the device by PBW still maintain spin manipulating capability, which is an important step toward realizing SiC devices internally equipped with a VSi-based quantum sensor.

We present a study of electrically active radiation-induced defects formed in 4H-SiC epitaxial layers following irradiation with fast neutrons, as well as 600 keV H+ and 2 MeV He++ ion implantations. We also look at electron emission energies and mechanisms of the carbon vacancy in 4H-SiC by means of first-principles modelling. Combining the relative stability of carbon vacancies at different sites with the relative amplitude of the observed Laplace-DLTS peaks, we were able to connect Z1 and Z2 to emissions from double negatively charged carbon vacancies located at the h- and k-sites, respectively.

Luminescence centers formed in the vicinity of SiC surface are expected to be utilized as Single Photon Sources (SPSs) because of the high-brightness and the potential of electric control at room temperature. In order to gain more insight into the surface SPSs, 4H-SiC pin-diodes are fabricated and the surface SPSs formed in the pin diodes are investigated using a confocal laser scanning fluorescence microscope (CFM). Locations where the surface SPSs appear as well as photoluminescence spectra of the observed surface SPSs are presented. Antibunching characteristics of the surface SPSs are also investigated by the second order autocorrelation function measurement. We conclude that two different types of surface SPSs appear in the surface of 4H-SiC. The location dependence of the observed surface SPSs indicates that the oxide layer on 4H-SiC plays an important role in the formation of surface SPSs, whereas neither ion implantation nor donor ions had an effect. The peak wavelength of luminescence spectra widely varies depending on their locations, indicating lattice strain introduced by the oxide layer has the potential to affect the luminescence spectra.

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The authors performed a long‐term follow‐up study to evaluate the efficacy and late toxicity of high‐dose rate intracavitary brachytherapy (HDR‐ICBT) for cervical carcinoma.From 1968 to 1986, 1148 patients with Stage IB to IVB squamous cell carcinoma of the cervix (staging was performed according to the International Federation of Gynecology and Obstetrics) were treated with a combination of external beam radiotherapy (EBRT) and HDR‐ICBT. For patients with early‐stage disease, 20 gray (Gy) of EBRT was delivered to the whole pelvis, followed by 24 Gy/4 fractions of HDR‐ICBT and 30 Gy of central‐shielding EBRT. For patients with advanced‐stage disease, 20–40 Gy of whole pelvic EBRT was administered, followed by 24 Gy/4 fractions of ICBT and 30–10 Gy of central‐shielding EBRT. The overall treatment time was approximately 6 weeks. Among survivors, the follow‐up rate was 98% and the median follow‐up duration was 22 years.The 10‐year pelvic tumor control rates were 93% for patients with Stage IB disease, 82% for patients with Stage II disease, and 75% for patients with Stage III disease. The 10‐year overall and cause‐specific survival rates were 74% and 89% for patients with Stage IB disease, 52% and 74% for patients with Stage II disease, and 42% and 59% for patients with Stage III disease, respectively. The 10‐year actuarial rates of major complications were 4.4% in the rectosigmoid colon, 0.9% in the bladder, and 3.3% in the small intestines.The results of the current study suggest that the combination of EBRT and HDR‐ICBT according to the authors' protocol provided outcomes that were comparable to those of the conventional low‐dose rate brachytherapy with acceptable rates of late complications in the treatment of cervical carcinoma. Cancer 2005. © 2004 American Cancer Society.

Background:A nationwide effort is in progress to establish the actual state of radiotherapy and its quality assurance (QA) in Japan by using the Patterns of Care Study (PCS). In this study, national averages are calculated with a limited number of patients. A calculation program for national averages was prepared and applied to the radiotherapeutic processes used for esophageal cancer patients entered in the PCS.Methods:The calculation program for national averages, which were revised on the basis of differences between individual facilities and institutional strata, was developed in accordance with Sedransk's equation for the original PCS in the USA. National averages for several aspects concerning the sampled patients who had esophageal cancer between 1992 and 1994 were calculated with these procedures. Data for facilities and stratification of institution were simulated from a national structure survey of radiation oncology in 1990.Results:Values of the national average by Sedransk's equation were different from those of the simple sample average. There were significant differences in radiotherapeutic processes among stratification of institutions. For esophageal cancer, national averages were 0.129 for applications of endoscopic ultrasound, 0.599 for ‘all fields treated each day’ and 0.088 for application of brachytherapy.Conclusion:National averages for radiotherapy could be calculated. The values obtained in this PCS will be a useful measure for future QA in radiation oncology and in other specialties in Japan.