Hitoshi Takane

Rutile-structured germanium oxide $(\mathrm{r}\text{\ensuremath{-}}{\mathrm{GeO}}_{2})$, an ultrawide band-gap (UWBG) semiconductor, is a promising candidate for future high-power electronics because of its excellent properties, including ambipolar dopability, high carrier mobilities, and a higher thermal conductivity than $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$. In this paper, focusing on a wide variety of its applications, we propose an UWBG alloy system base

Abstract Recently, α -Ga 2 O 3 has been attracting great attentions as a new wide bandgap semiconductor, however, the reason why metastable α -Ga 2 O 3 is grown by mist chemical vapor deposition (CVD) has not been understood. In this study, in order to elucidate growth mechanism of mist CVD-grown α -Ga 2 O 3 , growth processes in the initial stage were investigated by atomic force microscopy, transmission electron microscopy, and X-ray diffraction reciprocal space mapping. We found that the char

Abstract Mist CVD was applied to grow the β -Ga 2 O 3 channel layer of a MESFET on a semi-insulating β -Ga 2 O 3 (010) substrate. The mobility and carrier concentration of the channel layer were 80 cm 2 V –1 s –1 and 6.2 × 10 17 cm −3 , respectively. The device exhibited a pinch-off characteristic with a threshold gate voltage of −9 V, and the maximum drain current was 240 mA mm −1 . The maximum transconductance was 46 mS mm −1 and the on-resistance was 30 Ω mm. This device performance suggests

Abstract We report the characterization and application of mist-CVD-grown rutile-structured Ge x Sn 1− x O 2 ( x = ∼ 0.53) films lattice-matched to isostructural TiO 2 (001) substrates. The grown surface was flat throughout the growth owing to the lattice-matching epitaxy. Additionally, the film was single-crystalline without misoriented domains and TEM-detectable threading dislocations due to the coherent heterointerface. Using the Ge 0.49 Sn 0.51 O 2 film with a carrier density of 7.8 × 10 18

We discuss the structure of threading dislocations in α-Ga2O3 thin films grown on c- and m-plane sapphire substrates. The thickness-dependent threading dislocation density in both films directly affects the electrical properties of the films including carrier concentration and mobility. Two distinct types of threading dislocations are identified for each of the c- and m-plane α-Ga2O3 thin films. The c-plane α-Ga2O3 thin film shows Burgers vectors of 1/3[11¯01] and 1/3[112¯0], while the m-plane α

Rutile-type GeO2 (r-GeO2) with an ultrawide bandgap of ∼4.7 eV has emerged as a promising material for next-generation power-electronic and optoelectronic devices. We performed transmission electron microscopy (TEM) observation to analyze the structural properties of r-GeO2 film on r-TiO2 (001) substrate at an atomic level. The r-GeO2 film exhibits a threading dislocation density of 3.6 × 109 cm−2 and there exist edge-, screw-, and mixed-type dislocations in the film as demonstrated by two-beam

Rutile-type wide and ultrawide band-gap oxide semiconductors are emerging materials for high-power electronics and deep ultraviolet optoelectronics applications. A rutile-type GeO2-SnO2 alloy (r-GexSn1–xO2) recently found is one of such materials. Herein, we report low-temperature electron transport properties of r-GexSn1−xO2 thin films with x = 0.28 and 0.41. Based on resistivity and magnetoresistance measurements, along with the theory of quantum interference, it is suggested that Efros–Shklov

Deep traps in n‐type α‐Ga 2 O 3 grown by mist chemical vapor deposition are analyzed by the photocapacitance method and deep‐level optical spectroscopy. The trap levels at E c −(≈2.0 eV) ( E 1 ), E c −(≈2.5 eV) ( E 2 ), and E c −(≈3.2 eV) ( E 3 ) are evident and their concentrations are 3.5 × 10 14 , 3.6 × 10 14 , and 6.2 × 10 15 cm −3 , respectively, which are much lower than ever reported for α‐Ga 2 O 3 . The Frank–Condon shift of all three traps is large as seen for β‐Ga 2 O 3 , indicating a

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Abstract We demonstrated selective-area growth of r-SnO 2 on a SiO 2 -masked r-TiO 2 (110) substrate. The heteroepitaxy on a window started with a Volmer–Weber mode to grow islands with {100}-, {11̄0}-, and {011}-faceted sidewalls, whose growth shapes were consistent with the rutile structure’s equilibrium shape. The islands coalesced each other to make a flat (110) top surface on a striped window, and lateral overgrowth started after the complete coverage of the window. Cross-sectional transmis