| 1. |
- Fulati, Alimujiang, et al.
(författare)
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Miniaturized pH Sensors Based on Zinc Oxide Nanotubes/Nanorods
- 2009
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Ingår i: SENSORS. - : MDPI AG. - 1424-8220. ; 9:11, s. 8911-8923
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Tidskriftsartikel (refereegranskat)abstract
- ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The developed ZnO nanotube and nanorod pH sensors display good reproducibility, repeatability and long-term stability and exhibit a pH-dependent electrochemical potential difference versus an Ag/AgCl reference electrode over a large dynamic pH range. We found the ZnO nanotubes provide sensitivity as high as twice that of the ZnO nanorods, which can be ascribed to the fact that small dimensional ZnO nanotubes have a higher level of surface and subsurface oxygen vacancies and provide a larger effective surface area with higher surface-to-volume ratio as compared to ZnO nanorods, thus affording the ZnO nanotube pH sensor a higher sensitivity. Experimental results indicate ZnO nanotubes can be used in pH sensor applications with improved performance. Moreover, the ZnO nanotube arrays may find potential application as a novel material for measurements of intracellular biochemical species within single living cells.
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| 2. |
- Pinos, Andrea, et al.
(författare)
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Time-resolved luminescence studies of proton-implanted GaN
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 95:11
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Tidskriftsartikel (refereegranskat)abstract
- Time-resolved photoluminescence measurements performed on proton implanted and annealed GaN layers have shown that carrier lifetime can be tuned over two orders of magnitude and, at implantation dose of 1 x 10(15) cm(-2), decreases down to a few picoseconds. With annealing at temperatures between 250 and 750 degrees C, carrier lifetime, contrary to electrical characteristics, is only slightly restored, indicating that electrical compensation and carrier dynamics are governed by different defects. Ga vacancies, free and bound at threading dislocations, are suggested as the most probable defects, responsible for electrical compensation and carrier lifetime quenching.
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| 3. |
- Usman, Muhammad, et al.
(författare)
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Electrical and structural characterization of ion implanted GaN
- 2009
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 267:8-9, s. 1561-1563
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Tidskriftsartikel (refereegranskat)abstract
- Ion implantation induced defects and their consequent electrical impact have been investigated. Unintentionally doped n-type gallium nitride was implanted with 100 keV Si+ and 300 keV Ar+ ions in a fluence range of 10(14)-10(15) ions/cm(2). The samples were characterized with Rutherford backscattering/Channeling method for damage buildup. Time of flight elastic recoil detection analysis was implied on the Si implanted samples to see the ion depth distribution. At implanted GaN samples were studied electrically with scanning spreading resistance microscopy. Our results show that an At fluence of 5 x 10(14) cm(-2) increases the resistance by five orders of magnitude to a maximum value. For the highest fluence, 6 x 10(15) cm(-2), the resistivity decreases by two orders of magnitude.
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