Kyushu University · Materials Science
Professor Phongsaphak Sittimart's research lab specializes in the development and characterization of wide-bandgap semiconductor heterostructures, with a focus on diamond-based and gallium oxide (β-Ga₂O₃) heterojunction devices. The lab explores innovative heteroepitaxial growth techniques—such as RF magnetron sputtering and direct bonding—to fabricate high-performance Schottky diodes, p-n junctions, and photodetectors with exceptional thermal stability, radiation hardness, and rectifying performance. Key research directions include interface engineering, defect control via buffer layers, and the integration of novel materials like FeSi₂ and N-doped diamond for advanced optoelectronic and power electronic applications.
Figures are computed from collected data and may differ slightly.
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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