九州大学 · 材料科学
Phongsaphak Sittimart教授の研究室では、炭素素材として優れた耐環境性と半導体特性を併せ持つダイヤモンドを基板に用いた異質接合デバイスの開発を主眼としています。特に、β-Ga₂O₃やFeSi₂などの酸化物半導体・ケイ化物半導体をダイヤモンド上に低温でエpitaxial成長させ、高耐久性・高効率な光検出器やショットキーバリアダイオードの実現を目指しています。また、界面特性の最適化や欠陊抑制技術の開発を通じて、高温・放射線環境下でも安定した動作を実現する次世代パワー半導体素子の創出を推進しています。
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Heterojunctions consisting of p-type diamond substrates and thin exfoliated n-type β-Ga2O3 layers were fabricated at a low temperature using a direct-bonding technique. We have fabricated p+-diamond/n-Ga2O3 (p+–n) and p-diamond/n-Ga2O3 (p–n) structures with different B concentrations in diamond. The p+–n heterojunction exhibited Ohmic behavior, resulting from p+-diamond behaving as a metallic layer. As for the p–n heterojunction, it showed clear rectifying action as a conventional bipolar action
Abstract Due to the limits of the physical properties of conventional semiconductors against harsh environments, seeking a suitable material for next‐generation photoconversion devices with high‐temperature stability and strong radiation hardness has become a hot issue. Here, visible‐light photodetectors are fabricated on an N‐doped diamond. Their visible‐light detection via charge‐neutralized impurity levels including multi‐complex mid‐gap states induced crystal defects shows photosensitivity o
Abstract In this study, pseudo-vertical diamond Schottky barrier diodes (SBDs) were fabricated on heteroepitaxial substrates and a metal impurity-incorporated buffer layer to suppress killer defects was inserted. All SBDs exhibited excellent rectifying actions with suppressed leakage current. The in-plane uniformity was improved after the insertion of the buffer layer. Forward characteristics were fitted by thermionic emission theory and Tung’s model in the temperature range from 300 to 480 K. T
Abstract In this work, we demonstrate the first achievement in heteroepitaxial growth of β -Ga 2 O 3 thin films on single crystalline diamond (111) wafers using RF magnetron sputtering. A single monoclinic ( β -phase) structure with a monofamily { <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mn>2</mml:mn> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> 01} plane was obtained. XRD pole figure shows ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/Math
n-Type nanocrystalline FeSi2/p-type Si heterojunctions were formed by using facing-target direct- current sputtering at room temperature. The J-V characteristic results revealed that the reverse leakage current is large and the response under illumination of near-infrared light is very weak. The capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G-V-f) measurements were carried out at room temperature in order to estimate the series resistance (Rs) by using the Nicollian-Br
In this study, n-type β -FeSi 2 /p-type Si heterojunctions, inside which n-type β -FeSi 2 films were epitaxially grown on p-type Si(111) substrates, were created using radio frequency magnetron sputtering at a substrate temperature of 560°C and Ar pressure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn fontstyle="italic">2.66</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn fontstyle="italic">10</mml:mn></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn fontstyle="i
Pseudo-vertical diamond Schottky barrier diodes (SBDs) were fabricated on a CVD-grown diamond substrate. The radiation hardness of the diamond SBDs was examined using hard X-ray irradiation at a radiation absorption dose of 10 MGy. Before the irradiation, ideality factor (n), Schottky barrier height (ϕ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</inf>), breakdown voltage, and breakdown field (E<inf xmlns:mml="http://www.w3.org/1998/Math/MathML"
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