Browsing by Author "Chang, Chun-Hsiang"

Now showing 1 - 4 of 4

Investigation of light absorption properties and acceptance angles of nanopatterned GZO/a-Si/p(+)-Si photodiodes
(2010-05-28)
Chen, Cheng-Pin
;
Lin, Pei-Hsuan
;
Hung, Yen-Jen
;
Hsu, Shao-Shun
;
Chen, Liang-Yi
In this work, n-GZO/a:amorphous-Si(i:intrinsic)/p(+)-Si photodiodes are fabricated. We employed a nanosphere lithographic technique to obtain nanoscale patterns on either the a-Si(i) or p(+)-Si surface. As compared with the planar n-GZO/p(+)-Si diode, the devices with nanopatterned a-Si(i) and nanopatterned p(+)-Si substrates show a 32% and 36.2% enhancement of photoresponsivity. Furthermore, the acceptance angle measurement reveals that the nanostructured photodiodes have larger acceptance angles than the planar structure. It also shows that the device with the nanocone structure has a higher acceptance angle than that with the nanorod structure.
Investigation of low-temperature electroluminescence of InGaN/GaN based nanorod light emitting arrays
(2011-01-28)
Huang, Ying-Yuan
;
Chen, Liang-Yi
;
Chang, Chun-Hsiang
;
Sun, Yu-Hsuan
;
Cheng, Yun-Wei
For InGaN/GaN based nanorod devices using a top-down etching process, the optical output power is affected by non-radiative recombination due to sidewall defects (which decrease light output efficiency) and the mitigated quantum confined Stark effect (QCSE) due to strain relaxation (which increases internal quantum efficiency). Therefore, the exploration of low-temperature optical behaviors of nanorod light emitting diodes (LEDs) will help identify the correlation between these two factors. In this work, low-temperature electroluminescent (EL) spectra of InGaN/GaN nanorod arrays were explored and compared with those of planar LEDs. The nanorod LED exhibits a much higher optical output percentage increase when the temperature decreases. The increase is mainly attributed to the increased carriers in the quantum wells for radiative recombination. Also, due to a better spatial overlap of electrons and holes in the quantum wells, the increased number of carriers can be more efficiently recombined in the nanorod device. Next, while the nanorod array shows nearly constant peak energy in the EL spectra at various injection currents at the temperature of 300 K, a blue shift has been observed at 190 K. The results suggest that with less non-radiative recombination and thus more carriers in the quantum wells, carrier screening and band filling still prevail in the partially strain relaxed nanorods. Moreover, when the temperature drops to 77 K, the blue shift of both nanorod and planar devices disappears and the optical output power decreases since there are fewer carriers in the quantum wells for radiative recombination.
Iron embedded magnetic nanodiamonds for in vivo MRI contrast enhancement
(2019-12-11)
Lin, Bo-Rong
;
Chen, Chien-Hsu
;
Chang, Chun-Hsiang
;
Kunuku, Srinivasu
;
Chen, Tzung-Yuang
Although nanodiamonds have long being considered as a potential tool for biomedical research, the practical in vivo magnetic resonance imaging (MRI) application of nanodiamonds remains relatively unexplored. In this paper, we present the first application of in vivo MRI contrast enhancement using only iron embedded magnetic nanodiamonds. An MR image enhancement was clearly demonstrated in the rendering of T2-weighted images of mice obtained using an unmodified commercial MRI scanner. The excellent contrast obtained using these nanodiamonds opens the door to the non-invasive in vivo tracking of nanodiamonds and image enhancement. In the future, one can apply these magnetic nanodiamonds together with surface modifications to facilitate drug delivery, targeted therapy, localized thermal treatment, and diagnostic imaging.
Secondary ion mass spectrometry to verify the implantation of magnetic ions in nanodiamonds
(2019-11-07)
Lin, Bo-Rong
;
Wang, Chiung-Chi
;
Chen, Chien-Hsu
;
Kunuku, Srinivasu
;
Hsiao, Tung-Yuan
Ion implantation is used to create nanodiamonds (NDs) with embedded magnetic ions for use in a wide range of biological and medical applications; however, the effectiveness of this process depends heavily on separating magnetic NDs from nonmagnetic ones. In this study, we use secondary ion mass spectrometry to verify the implantation of magnetic ions in NDs and the success of separation. When applied to a series of NDs with embedded iron or manganese ions, the sorting tool used in this study proved highly effective in selecting magnetic NDs. Besides, multienergy ion implantation and precise thickness control of NDs coating on the silicon wafer were suggested to improve this technology. Published under license by AIP Publishing.