High-hole mobility polycrystalline Ge on an insulator formed by controlling precursor atomic density for solid-phase crystallization

High-carrier mobility semiconductors on insulators are essential for fabricating advanced thin-film transistors, allowing for three-dimensional integrated circuits or high-performance mobile terminals. We investigate the low-temperature (375–450 °C) solid-phase crystallization (SPC) of Ge on a glass substrate, focusing on the precursor conditions. The substrate temperature during the precursor deposition, Td, ranged from 50 to 200 °C. According to the atomic density of the precursor and the Td dependent SPC properties, the precursor conditions were determined by three regimes: the low-density regime (Td  125 °C). The use of the precursor in the narrow high-density regime enabled us to form SPC-Ge with a hole mobility of 340 cm2/Vs, the highest value among semiconductor thin films grown on insulators at low temperature (<900 °C). The origins of the high hole mobility were determined to be both a large grain size (5 µm) and a low energy barrier height (6.4 meV) for the grain boundary. The findings from and knowledge gained in this study, that is, the influence of the precursor conditions on subsequent crystal growth, will be universal and applicable to various materials

A Case of Thrombotic Thrombocytopenia Purpura Associated with Systemic Lupus Erythematosus: Diagnostic Utility of ADAMTS-13 Activity

Thrombotic thrombocytopenia purpura (TTP) caused by a deficiency in ADAMTS-13 activity is considered to involve a subset of thrombotic microangiopathy (TMA). Although concept of TTP is included under the umbrella of TMA, discrimination of TTP from TMA is occasionally difficult in an autoimmune disorder. Herein, we report a case with TTP associated with systemic lupus erythematosus (SLE). In this case, it was difficult to discriminate TTP from TMA and the measurement of ADAMTS-13 activity was useful for obtaining an accurate diagnosis. SLE patients having thrombocytopenia in complication with anemia should be considered a monitoring of ADAMTS-13 activity even though the patients lacked symptoms of TTP related to the microvascular coagulation

High-hole mobility Si1-xGex (0.1 ≤ x ≤ 1) on an insulator formed by advanced solid-phase crystallization

The grain size and hole mobility of polycrystalline Si1-xGex thin films formed on glass by solid-phase crystallization were significantly improved after preparing the amorphous precursors by heating the substrate. By just controlling the deposition temperature of the precursors (50–350 °C) for each SiGe composition, the grain size reached over 2 μm across the whole composition range. Reflecting the enlargement of the grain size, the hole mobility values were improved by approximately one order of magnitude. These values are comparable to those of single-crystal SiGe formed by Ge condensation and are the highest among SiGe on insulators synthesized at low temperature (<900 °C). The SiGe on insulator technology obtained in this study will greatly contribute to the development of SiGe-based electronic and optical devices

High hole mobility (≥500 cm2 V−1 s−1) polycrystalline Ge films on GeO2-coated glass and plastic substrates

The highest recorded hole mobility in semiconductor films on insulators has been updated significantly. We investigate the solid-phase crystallization of a densified amorphous Ge layer formed on GeO2-coated insulating substrates. The resulting polycrystalline Ge layer with a glass substrate consists of large grains (~10 μm) and exhibits a hole mobility as high as 620 cm2 V−1 s−1, despite a low process temperature (500 °C). Even for the Ge layer formed on a flexible polyimide substrate at 375 °C, the hole mobility reaches 500 cm2 V−1 s−1. These achievements will aid in realizing advanced electronics, simultaneously allowing for high performance, inexpensiveness, and flexibility

Advanced solid-phase crystallization for high-hole mobility (450 cm2 V−1 s−1) Ge thin film on insulator

The hole mobility of the solid-phase-crystallized Ge layer is significantly improved by controlling the deposition temperature of Ge (50–200 °C) and the Ge thickness (50–500 nm) and by applying post annealing at 500 °C. The resulting hole mobility — 450 cm2 V−1 s−1 — is the highest reported value to date among semiconductor layers directly formed on glass. The mechanism of the mobility enhancement is discussed from the perspective of three carrier scattering factors: grain boundary scattering, interface scattering, and impurity scattering. The high-hole mobility Ge layer formed via the simple fabrication process is useful for high-speed thin-film transistors

Improving carrier mobility of polycrystalline Ge by Sn doping

To improve the performance of electronic devices, extensive research efforts have recently focused on the effect of incorporating Sn into Ge. In the present work, we investigate how Sn composition x (0 ≤ x ≤ 0.12) and deposition temperature Td (50 ≤ Td ≤ 200 °C) of the Ge1−xSnx precursor affect subsequent solid-phase crystallization. Upon incorporating 3.2% Sn, which is slightly above the solubility limit of Sn in Ge, the crystal grain size increases and the grain-boundary barrier decreases, which increases the hole mobility from 80 to 250 cm2/V s. Furthermore, at Td = 125 °C, the hole mobility reaches 380 cm2/V s, which is tentatively attributed to the formation of a dense amorphous GeSn precursor. This is the highest hole mobility for semiconductor thin films on insulators formed below 500 °C. These results thus demonstrate the usefulness of Sn doping of polycrystalline Ge and the importance of temperature while incorporating Sn. These findings make it possible to fabricate advanced Ge-based devices including high-speed thin-film transistors

A Small Bowel Ulcer due to Clopidogrel with Cytomegalovirus Enteritis Diagnosed by Capsule and Double-Balloon Endoscopy

We report the first case of small bowel ulcers due to clopidogrel in a 74-year-old man. He presented with diarrhea and melena after having been taking low-dose aspirin (LDA) and clopidogrel. There was no evidence of bleeding in the stomach, duodenum, or colon. Capsule endoscopy showed multiple ulcers and erosions in the small intestine. Double-balloon endoscopy revealed multiple ulcers throughout the ileum. Examination of the biopsy specimen showed cytomegalovirus infection. His LDA was discontinued and he was prescribed ganciclovir. However, the small bowel ulcers were aggravated. Therefore, clopidogrel was discontinued. The small bowel ulcers subsequently healed completely, forming scars

A Multidisciplinary Approach to Hip Fractures: Evaluating Outcomes on Mortality and Secondary Hip Fractures

Fracture liaison services (FLS) have been introduced in Japan and several other countries to reduce medical complications and secondary fractures. We aimed to evaluate the effects of the implementation of an FLS approach on patient outcomes during hospitalization at our hospital and over a 2-year follow-up post-injury. This retrospective cohort study included patients ≥ 60 years admitted to our hospital for hip fragility fractures between October 1, 2016, and July 31, 2020. Patient groups were defined as those treated before (control group, n=238) and after (FLS group, n=196) establishment of the FLS protocol at our institution. The two groups were compared in terms of time to surgery, length of hospital stay, and the incidence of complications after admission, including secondary hip fracture and mortality rates. The follow-up period was 24 months. FLS focuses on early surgery within 48 h of injury and assessing osteoporosis treatment before injury to guide post-discharge anti-osteoporosis medication. FLS reduced the length of hospital stay (p<0.001) and the prevalence of complications after admission (p<0.001), particularly cardiovascular disease, and it increased adherence to anti-osteoporosis medication. These FLS effects resulted in lower secondary hip fracture and mortality rates at 12 and 24 months post-injury. FLS for fragility hip fractures can improve patient outcomes during hospitalization and over a 2-year follow-up period