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Anti-reflective nano- and micro-structures on 4H-SiC for photodiodes.

Kang MS, Joo SJ, Bahng W, Lee JH, Kim NK, Koo SM - Nanoscale Res Lett (2011)

Bottom Line: In this study, nano-scale honeycomb-shaped structures with anti-reflection properties were successfully formed on SiC.We demonstrate that the reflection characteristic of the fabricated photodiodes has significantly reduced by 55% compared with the reference devices.As a result, the optical response Iillumination/Idark of the 4H-SiC photodiodes were enhanced up to 178%, which can be ascribed primarily to the improved light trapping in the proposed nano-scale texturing.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Electronics and Information, Kwangwoon University, Seoul 139-701, Korea. smkoo@kw.ac.kr.

ABSTRACT
In this study, nano-scale honeycomb-shaped structures with anti-reflection properties were successfully formed on SiC. The surface of 4H-SiC wafer after a conventional photolithography process was etched by inductively coupled plasma. We demonstrate that the reflection characteristic of the fabricated photodiodes has significantly reduced by 55% compared with the reference devices. As a result, the optical response Iillumination/Idark of the 4H-SiC photodiodes were enhanced up to 178%, which can be ascribed primarily to the improved light trapping in the proposed nano-scale texturing.

No MeSH data available.


Comparison of spectral reflectivity from 300 to 1000 nm for different surface structures.
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Figure 3: Comparison of spectral reflectivity from 300 to 1000 nm for different surface structures.

Mentions: Figure 2 shows scanning electron microscopy (SEM) images of the surface morphology of nano-honeycomb structures. Three different types of samples on SiC with different surface structures were examined: (a) reference structures, (b) micro-honeycomb structures, and (c) nano-honeycomb structures. The reflectance spectral dependence was studied using a UV-Vis/NIR spectrometer (AvaSpec-3648) and by AFM (N8 ARGOS) analysis. Figure 3 shows the corresponding reflectance spectra of the samples, along with those of the reference cells [10,11]. In the region of wavelengths from 300 to 1000 nm, the reflectance of the micro-honeycomb structures was reduced by 30% with respect to that of the reference cell. After performing the unmasked ICP etching for additional nano-scale roughening on the micro-honeycomb structures, the reflectance decreased by 55% with respect to the reference cell. The optical measurements of the nano-honeycomb structures show that the amount of absorbed light significantly increased. The decreased reflectance of the structure is ascribed to the increased roughness of the surface due to the structures formed on the surface. Figure 4 shows the surface morphology observed with an atomic force microscope (AFM) under the contact mode with a scan area of 12 × 12 μm2. The root mean square (RMS) of the surface roughness was calculated from the AFM images as shown in Figure 4d.


Anti-reflective nano- and micro-structures on 4H-SiC for photodiodes.

Kang MS, Joo SJ, Bahng W, Lee JH, Kim NK, Koo SM - Nanoscale Res Lett (2011)

Comparison of spectral reflectivity from 300 to 1000 nm for different surface structures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211295&req=5

Figure 3: Comparison of spectral reflectivity from 300 to 1000 nm for different surface structures.
Mentions: Figure 2 shows scanning electron microscopy (SEM) images of the surface morphology of nano-honeycomb structures. Three different types of samples on SiC with different surface structures were examined: (a) reference structures, (b) micro-honeycomb structures, and (c) nano-honeycomb structures. The reflectance spectral dependence was studied using a UV-Vis/NIR spectrometer (AvaSpec-3648) and by AFM (N8 ARGOS) analysis. Figure 3 shows the corresponding reflectance spectra of the samples, along with those of the reference cells [10,11]. In the region of wavelengths from 300 to 1000 nm, the reflectance of the micro-honeycomb structures was reduced by 30% with respect to that of the reference cell. After performing the unmasked ICP etching for additional nano-scale roughening on the micro-honeycomb structures, the reflectance decreased by 55% with respect to the reference cell. The optical measurements of the nano-honeycomb structures show that the amount of absorbed light significantly increased. The decreased reflectance of the structure is ascribed to the increased roughness of the surface due to the structures formed on the surface. Figure 4 shows the surface morphology observed with an atomic force microscope (AFM) under the contact mode with a scan area of 12 × 12 μm2. The root mean square (RMS) of the surface roughness was calculated from the AFM images as shown in Figure 4d.

Bottom Line: In this study, nano-scale honeycomb-shaped structures with anti-reflection properties were successfully formed on SiC.We demonstrate that the reflection characteristic of the fabricated photodiodes has significantly reduced by 55% compared with the reference devices.As a result, the optical response Iillumination/Idark of the 4H-SiC photodiodes were enhanced up to 178%, which can be ascribed primarily to the improved light trapping in the proposed nano-scale texturing.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Electronics and Information, Kwangwoon University, Seoul 139-701, Korea. smkoo@kw.ac.kr.

ABSTRACT
In this study, nano-scale honeycomb-shaped structures with anti-reflection properties were successfully formed on SiC. The surface of 4H-SiC wafer after a conventional photolithography process was etched by inductively coupled plasma. We demonstrate that the reflection characteristic of the fabricated photodiodes has significantly reduced by 55% compared with the reference devices. As a result, the optical response Iillumination/Idark of the 4H-SiC photodiodes were enhanced up to 178%, which can be ascribed primarily to the improved light trapping in the proposed nano-scale texturing.

No MeSH data available.