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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.


4H-SiC photodiode structure and the optical response characteristics. (a) Structure of the 4H-SiC Schottky-type photodiode with an open area of 250 × 250 μm2. (b) Optical response of the 4H-SiC photo-diodes with different surface structures.
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Figure 5: 4H-SiC photodiode structure and the optical response characteristics. (a) Structure of the 4H-SiC Schottky-type photodiode with an open area of 250 × 250 μm2. (b) Optical response of the 4H-SiC photo-diodes with different surface structures.

Mentions: Schottky-type ultraviolet photodiodes were fabricated on n-type 4H-SiC wafers with a 12-μm-thick n- epilayer (ND = 4.25 × 1015 cm-3) grown on n+ substrate (ND = 1018 cm-3) [13]. A large area ohmic contact on the back-side was formed by the sputter of a 100-nm Ni film, followed by a rapid thermal annealing process at 950°C in N2 for 90 s. The Schottky contacts on the front-side was fabricated by the electron-beam evaporation of a 50-nm Ni film, and a subsequent photolithographic patterning was performed to form rectangular ring patterns with widths of 550 μm and open area widths of 250 μm. Figure 5a shows the fabricated 4H-SiC Schottky photodiode structure. The open area directly exposed to radiation was estimated to be about 21% of the total device area. The current-voltage characteristics of the devices were measured by using a Keithley 4200 measuring unit. The saturated currents of the Schottky photodiodes were measured as a function of the reverse bias, both in the dark condition Idark and under UV illumination at 300 nm Iillumination [14]. Figure 5b compares the optical response (Iillumination/Idark) of the photodiodes measured from the micro-honeycomb structures and nano-honeycomb structures.


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)

4H-SiC photodiode structure and the optical response characteristics. (a) Structure of the 4H-SiC Schottky-type photodiode with an open area of 250 × 250 μm2. (b) Optical response of the 4H-SiC photo-diodes with different surface structures.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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Figure 5: 4H-SiC photodiode structure and the optical response characteristics. (a) Structure of the 4H-SiC Schottky-type photodiode with an open area of 250 × 250 μm2. (b) Optical response of the 4H-SiC photo-diodes with different surface structures.
Mentions: Schottky-type ultraviolet photodiodes were fabricated on n-type 4H-SiC wafers with a 12-μm-thick n- epilayer (ND = 4.25 × 1015 cm-3) grown on n+ substrate (ND = 1018 cm-3) [13]. A large area ohmic contact on the back-side was formed by the sputter of a 100-nm Ni film, followed by a rapid thermal annealing process at 950°C in N2 for 90 s. The Schottky contacts on the front-side was fabricated by the electron-beam evaporation of a 50-nm Ni film, and a subsequent photolithographic patterning was performed to form rectangular ring patterns with widths of 550 μm and open area widths of 250 μm. Figure 5a shows the fabricated 4H-SiC Schottky photodiode structure. The open area directly exposed to radiation was estimated to be about 21% of the total device area. The current-voltage characteristics of the devices were measured by using a Keithley 4200 measuring unit. The saturated currents of the Schottky photodiodes were measured as a function of the reverse bias, both in the dark condition Idark and under UV illumination at 300 nm Iillumination [14]. Figure 5b compares the optical response (Iillumination/Idark) of the photodiodes measured from the micro-honeycomb structures and nano-honeycomb structures.

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.