Hiroshi Ikenoue

A Sensitive Thyroid Stimulating Hormone Assay for Screening of Thyroid Functional Disorder in Elderly Japanese

The use of a screening test for thyroid functional disorder by sensitive thyroid stimulating hormone assay in the elderly was investigated. The basal thyroid stimulating hormone levels predicted the response of thyroid stimulating hormone to thyrotropin releasing hormone; it was suppressed in 99 (99.0%) of 100 hyperthyroid patients. Therefore, not only primary hypothyroidism but also hyperthyroidism can be excluded when the serum thyroid stimulating hormone levels are normal.

Large grain growth of Ge-rich Ge1-xSnx (x 0.02) on insulating surfaces using pulsed laser annealing in flowing water

We investigate Sn incorporation effects on the growth characteristics of Ge-rich Ge1−xSnx (x < 0.02) on SiO2 crystallized by pulsed laser annealing (PLA) in air and water. Despite the very low Sn content of 2%, Sn atoms within the GeSn layers play a role in preventing ablation and aggregation of the layers during these PLA. Raman and electron backscatter diffraction measurements demonstrate achievement of large-grain (∼800 nmϕ) growth of Ge0.98Sn0.02 polycrystals by using PLA in water. These polycrystals also show a tensile-strain of ∼0.68%. This result opens up the possibility for developing GeSn-based devices fabricated on flexible substrates as well as Si platforms.

Immunological and chemical types of reversible hypothyroidism; clinical characteristics and long‐term prognosis

OBJECTIVE Spontaneous improvement occurs in about one‐half of patients with primary hypothyroidism who reside in an iodine‐sufficient area of Japan, but the pathogenetic factors related to reversible hypothyroidism are still not fully understood. We therefore investigated the clinical features and prognosis of patients with reversible hypothyroidism with or without iodine excess and antithyroid antibodies.

TSH DEPENDENT ELEVATION OF SERUM THYROGLOBULIN IN REVERSIBLE PRIMARY HYPOTHYROIDISM

Serum levels of thyroglobulin (Tg) were measured using immunoradiometric assay in 18 patients with primary hypothyroidism, whose serum levels of thyroid stimulating hormone (TSH) were higher than 40 mU/1 and anti‐Tg antibodies were negative. In 12 patients, serum Tg levels were extremely elevated above the upper limit of normal (30 ng/ml) and the levels were more than 800 ng/ml in 10 of them. In all of these 12 patients, thyroid function recovered spontaneously with only iodide restriction and the serum Tg levels declined concomitantly with the decrease in serum TSH concentrations, events suggesting the TSH dependency of this Tg elevation. In the other 6 patients without elevated Tg levels, thyroid function did not recover and replacement therapy with l‐thyroxine had to be given. Data from our study show that the TSH dependent Tg secretion is observed in reversible type primary hypothyroidism and that it may proceed vigorously even though thyroid hormone production is subnormal. Measurement of serum Tg may be valuable for predicting the prognosis of primary hypothyroidism.

Phosphorus doping of 4H SiC by liquid immersion excimer laser irradiation

Phosphorus doping of 4H SiC is performed by KrF excimer laser irradiation of 4H SiC immersed in phosphoric acid. Phosphorus is incorporated to a depth of a few tens of nanometers at a concentration of over 1020/cm3 without generating significant crystal defects. Formation of a pn junction diode with an ideality factor of 1.06 is demonstrated.

Patterned growth of ZnO nanowalls by nanoparticle-assisted pulsed laser deposition

We have succeeded in controlling the growth density of ZnO nanowires synthesized by nanoparticle-assisted pulsed laser deposition (NAPLD) using a ZnO buffer layer and laser irradiation. The density of the nanowires decreased with increasing thickness of the buffer layer. In addition, the nanowire density also decreased by laser irradiation to the buffer layer. Patterned growth of ZnO nanowalls using NAPLD was successfully achieved with the help of the buffer layer patterned by interfering laser beams.

Crystallization to polycrystalline silicon thin film and simultaneous inactivation of electrical defects by underwater laser annealing

We propose a low-temperature laser annealing method of a underwater laser annealing (WLA) for polycrystalline silicon (poly-Si) films. We performed crystallization to poly-Si films by laser irradiation in flowing deionized-water where KrF excimer laser was used for annealing. We demonstrated that the maximum value of maximum grain size of WLA samples was 1.5 μm, and that of the average grain size was 2.8 times larger than that of conventional laser annealing in air (LA) samples. Moreover, WLA forms poly-Si films which show lower conductivity and larger carrier life time attributed to fewer electrical defects as compared to LA poly-Si films.

Low-temperature (∼180 °C) position-controlled lateral solid-phase crystallization of GeSn with laser-anneal seeding

To realize next-generation flexible thin-film devices, solid-phase crystallization (SPC) of amorphous germanium tin (GeSn) films on insulating substrates combined with seeds formed by laser annealing (LA) has been investigated. This technique enables the crystallization of GeSn at controlled positions at low temperature (∼180 °C) due to the determination of the starting points of crystallization by LA seeding and Sn-induced SPC enhancement. The GeSn crystals grown by SPC from LA seeds showed abnormal lateral profiles of substitutional Sn concentration. These lateral profiles are caused by the annealing time after crystallization being a function of distance from the LA seeds. This observation of a post-annealing effect also indicates that GeSn with a substitutional Sn concentration of up to ∼10% possesses high thermal stability. These results will facilitate the fabrication of next-generation thin-film devices on flexible plastic substrates with low softening temperatures (∼250 °C).

Phosphorus Doping into 4H-SiC by Irradiation of Excimer Laser in Phosphoric Solution

We developed a method to dope phosphorus into 4H-SiC by irradiating excimer laser light to 4H-SiC immersed in phosphoric acid solution. A KrF excimer laser was used. The surface is slightly ablated by the laser irradiation. However, no amorphous layer is generated near the surface. Phosphorous is introduced at a concentration of over 1020 cm-3 near the crystal surface. The laser irradiation in phosphoric acid solution significantly improves the ohmic contact characteristic between metal and 4H-SiC. Hall effect measurement shows that the irradiation produces an n-type layer at the surface whose sheet carrier concentration is 2.25×1012 cm-2. In addition, we produce a pn junction by irradiating p-type 4H-SiC. The pn junction shows a rectifying characteristic whose on/off ratio is over 8 decades and ideality factor is 1.06.

Characterization of local electrical properties of polycrystalline silicon thin films and hydrogen termination effect by conductive atomic force microscopy

We observed local electrical properties of polycrystalline silicon films by conductive atomic force microscopy. Moreover, we investigated the effects of hydrogen termination on the polycrystalline silicon films. Before hydrogen termination, conductive regions in grain disappeared with the repeated scanning of the cantilever, while conductive regions in grain boundary almost unchanged. It is considered that hopping conduction is a major electrical conduction mechanism at grain boundaries. After 5 min hydrogen termination, locally nonterminated regions were observed near grain boundaries. This suggests that hydrogen termination of the polycrystalline silicon does not randomly progress, and there are regions that cannot be easily inactivated near grain boundaries.