Fluorine doping: A feasible solution to enhancing the conductivity of high-resistance wide bandgap Mg0.51Zn0.49O active components

N-type doping of high-resistance wide bandgap semiconductors, wurtzite high-Mg-content MgxZn1-xO for instance, has always been a fundamental application-motivated research issue. Herein, we report a solution to enhancing the conductivity of high-resistance Mg0.51Zn0.49O active components, which has been reliably achieved by fluorine doping via radio-frequency plasma assisted molecular beam epitaxial growth. Fluorine dopants were demonstrated to be effective donors in Mg0.51Zn0.49O single crystal film having a solar-blind 4.43 eV bandgap, with an average concentration of 1.0E19 F/cm3.The dramatically increased carrier concentration (2.85E17 cm-3 vs ~1014 cm-3) and decreased resistivity (129 ohm.cm vs ~10E6 ohm cm) indicate that the electrical properties of semi-insulating Mg0.51Zn0.49O film can be delicately regulated by F doping. Interestingly, two donor levels (17 meV and 74 meV) associated with F were revealed by temperature-dependent Hall measurements. A Schottky type metal-semiconductor-metal ultraviolet photodetector manifests a remarkably enhanced photocurrent, two orders of magnitude higher than that of the undoped counterpart. The responsivity is greatly enhanced from 0.34 mA/W to 52 mA/W under 10 V bias. The detectivity increases from 1.89E9 cm Hz1/2/W to 3.58eE10 cm Hz1/2/W under 10 V bias at room temperature.These results exhibit F doping serves as a promising pathway for improving the performance of high-Mg-content MgxZn1-xO-based devices.Comment: 8 page

Quasi-Epitaxial Growth of β-Ga2O3-Coated Wide Band Gap Semiconductor Tape for Flexible UV Photodetectors

The epitaxial growth of technically important β-Ga2O3 semiconductor thin films has not been realized on flexible substrates due to the limitations of high-temperature crystallization conditions and lattice-matching requirements. We demonstrate the epitaxial growth of β-Ga2O3(−201) thin films on flexible CeO2(001)-buffered Hastelloy tape. The results indicate that CeO2(001) has a small bi-axial lattice mismatch with β-Ga2O3(−201), inducing simultaneous double-domain epitaxial growth. Flexible photodetectors are fabricated on the epitaxial β-Ga2O3-coated tape. Measurements reveal that the photodetectors have a responsivity of 4 × 104 mA/W, with an on/off ratio reaching 1000 under 254 nm incident light and 5 V bias voltage. Such a photoelectrical performance is within the mainstream level of β-Ga2O3-based photodetectors using conventional rigid single-crystal substrates. More importantly, it remained robust against more than 20,000 bending test cycles. Moreover, the technique paves the way for the direct in situ epitaxial growth of other flexible oxide semiconductor devices in the future

Comparison of Female and Male <i>Batocera lineolata</i> (Coleoptera: Cerambycidae) Adults with a Combination of Morphological and Mitochondrial DNA Analysis

Abstract Morphological and genetic characters of male and female adults of Batocera lineolata Chevrolat were studied to determine intraspecific sex differences. Morphologically, the 9th and 10th segments of the antennae of male adults have odontoid processes that the female lacks. The longitudinal stripes of each abdominal segment of female adults appear to be connected between each adjacent segment, but those of the male do not appear continuous. Female adults also have a narrow V-shaped longitudinal groove in the 5th abdominal segment, whereas males do not. Amplification of the mitochondrial cytochrome c oxidase subunit I gene, cytochrome c oxidase subunit II gene, cytochrome b gene, and ribosomal 16S rRNA gene of four mitochondrial DNA showed sequences that differed between male and female adults. The similarity of the four genes between male and female adults is 98.7%, 99.1%, 98.4%, and 98.8%, respectively. The A+T contents of the four genes in female adults were all higher than in male adults. The difference in content of A+T versus C+G base pairs in female adults was higher than in males. This method of combined morphological and genetic analysis appears to be an accurate and straightforward tool for distinguishing male and female adults of B. lineolata.</jats:p