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In this work, we demonstrated Ga2O3-based power MOSFETs grown on c-plane sapphire substrates using in-situ TEOS doping for the first time. The β-Ga2O3:Si epitaxial layers were formed by the metalorganic chemical vapor deposition (MOCVD) with a TEOS as a dopant source. The depletion-mode Ga2O3 power MOSFETs are fabricated and characterized, showing the increase of the current, transconductance, and breakdown voltage at 150 °C. In addition, the sample with the TEOS flow rate of 20 sccm exhibited a breakdown voltage of more than 400 V at RT and 150 °C, indicating that the in-situ Si doping by TEOS in MOCVD is a promising method for Ga2O3 power MOSFETs. [ABSTRACT FROM AUTHOR]

In this paper, we propose and demonstrate to use of a single reflector with 68 segments to project vehicle low beam and high beam with the use of a GaN-based mini-LED matrix, which is a 5 × 6 LED die array. The design of the reflector is based on light field technology in considering etendue from the light source across the segments. The group of the segments with smaller etendue from the LED dies in the bottom 2 rows are used to project low beams. When the other LED dies are turned on, the reflector will project light upward and form the high beam. The selection of the turn-on LED dies in the mini-LED matrix can adjust the width of the illumination pattern so that an adaptive low/high beam can be performed. Besides, to extend the functionality of the headlamp module, we propose to dispense IR phosphor on LED dies in the high-beam zone of the GaN-based mini-LED matrix. Thus the vehicle can emit IR high beam, which can be imaged through a camera and can be incorporated with machine vision for an autonomous vehicle without using a complicated adaptive headlight to avoid glare. The proposed multi-function in spatial and spectral domains will be helpful to various applications with use of a mini-LED matrix. [ABSTRACT FROM AUTHOR]

To improve the electrical performance of power devices, materials used in fabrication need to be analyzed and optimized. By numerical simulations, we reveal that the breakdown voltage (BV) and location of a lateral diffused MOS power device simultaneously depend also on trench oxide permittivity. For a given device geometry, while the trench oxide permittivity with a certain value leads to a maximal BV, a smaller (larger) value causes electrical breakdown in the Si drift channel around the bottom (top) of the trench. This trend remains the same when Si is replaced by SiC. Our study implies that any by-product reducing the trench permittivity during trench filling should be avoided. [ABSTRACT FROM AUTHOR]

This study examined the effects of three cumulative γ-ray irradiation doses on AlGaN/GaN epilayer material and on high electron mobility transistor (HEMT) devices. After a cumulative γ-ray dose of 16 kGy, the Hall mobility increased from 1800 cm2/V s to 2100 cm2/V s, as determined through Hall measurement. Atomic force microscopy indicated an improvement in surface roughness but no change in the surface potential ∅ s . The HEMT device exhibited improvement in the drain current, with a subtle decreasing tendency in the leakage current. At high doses of γ-ray irradiation, the trends in the material and device parameters saturated. Moreover, the metal–semiconductor interface degraded, as confirmed through scanning electron microscopy image analysis. [ABSTRACT FROM AUTHOR]

Thimet oligopeptidase (Top) is a thiol-sensitive metallopeptidase with increased concentrations in brain and reproductive tissues. Prolyl endopeptidase (Pep) is another endopeptidase with high enzymatic activity in the brain. The two neuropeptidases are involved in the degradation of gonadotropin-releasing hormone. To clarify their roles in reproductive regulation, the spotted scat top (sstop) and pep (sspep) genes were cloned and analyzed. Tissue distribution by RT-PCR showed that sstop and sspep were more highly expressed in reproduction-related tissues than in other tissues. The sstop and sspep mRNA was detected in female hypothalamuses at phase II (oocytes at the perinuclear stage), phase III (oocytes forming the vitelline vesicle) and phase IV (oocytes at lipidic and proteic vitellogenesis stages). Both sstop and sspep were highly expressed in phase III, moderately in phase IV, and the lowest in phase II. The sstop and sspep genes were down-regulated in hypothalamuses after treatment with estradiol both in vitro and in vivo. It is suggested that Sstop and Sspep play significant roles in the regulation of reproduction and these results suggested an ssTop- and ssPep-mediated positive feedback mechanism of ovarian function. [ABSTRACT FROM AUTHOR]

Winged helix/forkhead transcription factor gene 2 (Foxl2) plays a crucial role during early ovarian development in fish. Sex steroids and aromatase inhibitors can regulate gonadal differentiation in teleosts. To address the role of Foxl2 in gonadal differentiation, foxl2 was isolated and characterized from the Hong Kong catfish, Clarias fuscus. Tissue distribution analysis by quantitative real-time PCR (qPCR) showed that the foxl2 mRNA was highest in the ovaries; moderate in the female pituitary and hypothalamus; but weak in the forebrain, liver, testis and male pituitary, with a sexually dimorphic pattern in which there was higher expression overall in females versus males. Treatment of the fries during the period of gonadal differentiation [2-30 days post hatching (dph)] with 17α-methyltestosterone (MT), an aromatase inhibitor (letrozole) and 17β-estradiol (E) affected the expression of foxl2. The expression of foxl2 was highest before gonadal differentiation (12 dph), but decreased significantly after gonadal differentiation (18-30 dph). In addition, MT and letrozole were able to down-regulate foxl2, but E up-regulated foxl2 during gonadal morphological differentiation. These results indicate the significant roles of Foxl2 in the gonadal differentiation of C. fuscus. [ABSTRACT FROM AUTHOR]