Current usage of stereotactic body radiotherapy for oligometastatic prostate cancer in Korea: patterns of care survey (KROG 19-08).

BACKGROUND: Growing evidence suggests that metastasis-directed therapy and/or prostate-directed therapy may benefit patients with oligometastatic prostate cancer (OMPC). Stereotactic body radiotherapy (SBRT) is increasingly used to treat oligometastases in various cancers. The purpose of this study was to investigate the current patterns of curative-intent SBRT for OMPC in Korea. METHODS: A 20-item questionnaire was sent to 326 radiation oncologists in 93 institutions in Korea. Only 1 physician per institution was required to complete the survey. Subsequently, the second survey consisting of 3 clinical scenarios was sent to 64 physicians with clinical experience in SBRT: case 1, cT4N0M1 (direct invasion to two pelvic bones); case 2, cT2N0M1 (three bone metastases); and case 3, solitary spine metastasis after radical prostatectomy. RESULTS: Seventy-six physicians from 93 institutions (82%) answered the first survey. The multidisciplinary team approach was practiced in 16 institutions (21%). Most physicians (75%) agreed on the definition of oligometastases as limited lesions and/or organs ≤5: 25% agreed with low-volume disease according to CHAARTED trial. During the last year, 49 physicians (64%) treated OMPC patients with curative intent. Sixty four physicians (84%) had a clinical experience with SBRT: 48 (75%) stated that both dose and fraction number should be considered when defining SBRT, whereas others (25%) stated that only fraction size should be considered. Fifty-five faculties (86%) answered the second survey. Physicians agreed with oligometastases in 89% for case 1, in 80% for case 2, and in 100% for case 3. The rate of SBRT application was the highest in case 3 (70%). CONCLUSIONS: There was diversity in the patterns of SBRT for OMPC in Korea. Additional prospective studies are necessary to strengthen evidence regarding role of SBRT in OMPC.

Vertical and bevel-structured SiC etching techniques incorporating different gas mixture plasmas for various microelectronic applications.

This study presents a detailed fabrication method, together with validation, discussion, and analysis, for state-of-the-art silicon carbide (SiC) etching of vertical and bevelled structures by using inductively coupled plasma reactive ion etching (ICP-RIE) for microelectronic applications. Applying different gas mixtures, a maximum bevel angle of 87° (almost vertical), large-angle bevels ranging from 40° to 80°, and small-angel bevels ranging from 7° to 17° were achieved separately using distinct gas mixtures at different ratios. We found that SF6 with additive O2 was effective for vertical etching, with a best etching rate of 3050 Å/min. As for the large-angle bevel structures, BCl3 + N2 gas mixtures show better characteristics, exhibiting a controllable and large etching angle range from 40° to 80° through the adjustment of the mixture ratio. Additionally, a Cl2 + O2 mixture at different ratios is applied to achieve a small-angel bevels ranging from 7° to 17°. A minimum bevel angel of approximately 7° was achieved under the specific volume of 2.4 sccm Cl2 and 3.6 sccm O2. These results can be used to improve performance in various microelectronic applications including MMIC via holes, PIN diodes, Schottky diodes, JFETs' bevel mesa, and avalanche photodiode fabrication.

Design and Fabrication of Implantable Neural Probes with Monolithically Integrated Light-Emitting Diodes for Optogenetic Applications.

We report an implantable neural probe with monolithically integrated light-emitting diodes (LEDs) and recording site for optogenetic applications. The device were designed and fabricated with 2-inch gallium nitride on silicon epitaxial wafer. The neural probe consisted of three µLEDs (a mesa size of 310 × 41 mm2) and four electrical recording sites, which had a total length of 6.72 mm (PCB bonding region + implanting region). The designed implantable neural probe was successfully processed by the conventional LED fabrication and Si microfabrcation. These methods can offer relatively rapid and easy fabrication. For fabricated µLEDs, the optical and electrical properties were measured and characterized. At 1 mA, the emission wavelength was around 460 nm and it was slightly blue-shifted with the increase of injection current. Also, the optical power density was about 1 mW/mm2 at an electrical input power of 3.5 mW, and it was increased to 6.3 mW/mm2 at 24 mW.

Selective photochemical synthesis of Ag nanoparticles on position-controlled ZnO nanorods for the enhancement of yellow-green light emission.

A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to preferentially form Ag NPs on ZnO nanorods. The ratio of visible emission to ultraviolet (UV) emission for the Ag NP-decorated ZnO nanorod arrays, synthesized for 30 min, is 20.5 times that for the ZnO nanorod arrays without Ag NPs. The enhancement of the visible emission is believed to associate with the surface plasmon (SP) effect of Ag NPs. The Ag NP-decorated ZnO nanorod arrays show significant SP-induced enhancement of yellow-green light emission, which could be useful in optoelectronic applications. The technique developed here requires low processing temperatures (120 °C and lower) and no high-vacuum deposition tools, suitable for applications such as flexible electronics.

Electrochemically synthesized broadband antireflective and hydrophobic GaOOH nanopillars for III-V InGaP/GaAs/Ge triple-junction solar cell applications.

We report the efficiency enhancement of III-V InGaP/GaAs/ Ge triple-junction (TJ) solar cells using a novel structure, i.e., vertically-oriented gallium oxide hydroxide (GaOOH) nanopillars (NPs), as an antireflection coating. The optical reflectance properties of rhombus-shaped GaOOH NPs, which were synthesized by a simple, low-cost, and large-scalable electrochemical deposition method, were investigated, together with a theoretical analysis using the rigorous coupled-wave analysis method. For the GaOOH NPs, the solar weighted reflectance of ~8.5% was obtained over a wide wavelength range of 300-1800 nm and their surfaces exhibited a high water contact angle of ~130° (i.e., hydrophobicity). To simply demonstrate the feasibility of device applications, the GaOOH NPs were incorporated into a test-grown InGaP/GaAs/Ge TJ solar cell structure. For the InGaP/GaAs/Ge TJ solar cell with broadband antireflective GaOOH NPs, the conversion efficiency (η) of ~16.47% was obtained, indicating an increased efficiency by 3.47% compared to the bare solar cell (i.e., η~13%).

Wafer-scale surface roughening for enhanced light extraction of high power AlGaInP-based light-emitting diodes.

A new approach to surface roughening was established and optimized in this paper for enhancing the light extraction of high power AlGaInP-based LEDs, by combining ultraviolet (UV) assisted imprinting with dry etching techniques. In this approach, hexagonal arrays of cone-shaped etch pits are fabricated on the surface of LEDs, forming gradient effective-refractive-index that can mitigate the emission loss due to total internal reflection and therefore increase the light extraction efficiency. For comparison, wafer-scale FLAT-LEDs without any surface roughening, WET-LEDs with surface roughened by wet etching, and DRY-LEDs with surface roughened by varying the dry etching time of the AlGaInP layer, were fabricated and characterized. The average output power for wafer-scale FLAT-LEDs, WET-LEDs, and DRY3-LEDs (optimal) at 350 mA was found to be 102, 140, and 172 mW, respectively, and there was no noticeable electrical degradation with the WET-LEDs and DRY-LEDs. The light output was increased by 37.3% with wet etching, and 68.6% with dry etching surface roughening, respectively, without compromising the electrical performance of LEDs. A total number of 1600 LED chips were tested for each type of LEDs. The yield of chips with an optical output power of 120 mW and above was 0.3% (4 chips), 42.8% (684 chips), and 90.1% (1441 chips) for FLAT-LEDs, WET-LEDs, and DRY3-LEDs, respectively. The dry etching surface roughening approach developed here is potentially useful for the industrial mass production of wafer-scale high power LEDs.

Electrochemically synthesized broadband antireflective and hydrophobic GaOOH nanopillars for III-V InGaP/GaAs/Ge triple-junction solar cell applications.

We report the efficiency enhancement of III-V InGaP/GaAs/ Ge triple-junction (TJ) solar cells using a novel structure, i.e., vertically-oriented gallium oxide hydroxide (GaOOH) nanopillars (NPs), as an antireflection coating. The optical reflectance properties of rhombus-shaped GaOOH NPs, which were synthesized by a simple, low-cost, and large-scalable electrochemical deposition method, were investigated, together with a theoretical analysis using the rigorous coupled-wave analysis method. For the GaOOH NPs, the solar weighted reflectance of ~8.5% was obtained over a wide wavelength range of 300-1800 nm and their surfaces exhibited a high water contact angle of ~130° (i.e., hydrophobicity). To simply demonstrate the feasibility of device applications, the GaOOH NPs were incorporated into a test-grown InGaP/GaAs/Ge TJ solar cell structure. For the InGaP/GaAs/Ge TJ solar cell with broadband antireflective GaOOH NPs, the conversion efficiency (η) of ~16.47% was obtained, indicating an increased efficiency by 3.47% compared to the bare solar cell (i.e., η~13%).

Light-extraction enhancement and directional emission control of GaN-based LEDs by self-assembled monolayer of silica spheres.

The light extraction of 1 × 1 mm(2) GaN-based blue light-emitting diodes (LEDs) was enhanced by a self-assembled monolayer (SAM) of silica submicron spheres. The silica spheres were synthesized with various spherical sizes via the ammonia-catalyzed hydrolysis and condensation of tetraethyl orthosilicate in water/ethanol solutions. Hexagonal closely-packed (HCP) silica sphere monolayer was formed onto the indium tin oxide layer of the LED by a spin coating process. The size effect of silica spheres on the light-extraction efficiency (LEE) of GaN-based LEDs was theoretically studied and their optimum size was determined. The simulation results showed that the use of silica spheres can improve the LEE by 1.1-1.32 times compared to the conventional LEDs. The light output power of the LED with 650-nm-thick SAM of HCP silica spheres was experimentally enhanced by 1.28 and 1.23 times under the injection currents of 100 and 350 mA, respectively. By employing the SAM of HCP silica spheres, the directional emission pattern was relatively converged, indicating a reasonable consistency with the simulation result.

Growth parameter dependent structural and optical properties of ZnO nanostructures on Si substrate by a two-zone thermal CVD.

We investigated the effect of growth parameters on the structural and optical properties of the ZnO nanostructures (NSs) grown on Au-coated Si substrate by a two-zone thermal chemical vapor deposition. The morphologies of ZnO NSs were controlled by various growth parameters, such as growth temperature, O2 flow rate, and working pressure, for different thicknesses of Au layer. The nanorod-like ZnO NSs were formed at 915 degrees C and the growth of two-dimensional structures, i.e., nanosheets, was enhanced with the increase of growth temperature up to 965 degrees C. It was found that the low working pressure contributed to improvement in vertical alignment and uniformity of ZnO NSs. The Zn/O atomic % ratio, which plays a key role in the growth mechanism of ZnO NSs, was changed by the growth parameters. The Zn/O atomic % ratio was increased with increasing the growth temperature, while it was decreased with increasing the working pressure. Under proper O2 flow rate, the ZnO nanorods with good crystallinity were fabricated with a Zn/O atomic % ratio of -0.9. For various growth parameters, the photoluminescence emission was slightly shifted with the ultraviolet emission related to the near band edge transition.

Improved light extraction of InGaN/GaN blue LEDs by GaOOH NRAs using a thin ATO seed layer.

We investigated the effect of gallium oxide hydroxide (GaOOH) nanorod arrays (NRAs) on the light extraction of InGaN/GaN multiple quantum well blue light-emitting diodes (LEDs). GaOOH NRAs were prepared on an indium tin oxide electrode (ITO) layer of LEDs by electrochemical deposition method. The GaOOH NRAs with preferred orientations were grown on the ITO surface by sputtering a thin antimony-doped tin oxide seed layer, which enhances heterogeneous reactions. Surface density and coverage were also efficiently controlled by the different growth voltages. For LEDs with GaOOH NRAs grown at -2 V, the light output power was increased by 22% without suffering from any serious electrical degradation and wavelength shift as compared with conventional LEDs.

Effect of AZO seed layer on electrochemical growth and optical properties of ZnO nanorod arrays on ITO glass.

We report the structural and optical properties of ZnO nanorod arrays (NRAs) grown by an electrochemical deposition process. The ZnO NRAs were grown on indium tin oxide (ITO) coated glass substrates with a thin sputtered Al-doped ZnO (AZO) seed layer and compared with ones directly grown without the seed layer. The growth condition dependence of ZnO NRAs was investigated for various synthetic parameters. The morphology and density of the ZnO NRAs were accordingly controlled by means of zinc nitrate concentration and growth time. From photoluminescence results, the ultraviolet emission was significantly enhanced after thermal treatment. For ZnO NRAs grown on ITO glass without the seed layer, the diffuse transmittance was enhanced despite the reduction in the total transmittance, indicating a high haze value. By using a thin AZO seed layer, the well-aligned ZnO NRAs on AZO/ITO glass are controllably and reproducibly synthesized by varying the growth parameters, exhibiting a total transmittance higher than 91% in the visible wavelength range as well as good optical and crystal quality.