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Enhanced performance of nitride-based ultraviolet vertical-injection light-emitting diodes by non-insulation current blocking layer and textured surface.

Chiang YC, Lin BC, Chen KJ, Lin CC, Lee PT, Kuo HC - Nanoscale Res Lett (2014)

Bottom Line: For the purpose of light extraction and efficiency enhancement, the nitride-based ultraviolet vertical-injection light-emitting diodes (UV-VLEDs) with non-insulation current blocking layer (n-CBL) and optimized textured surface were fabricated.The optical and electrical characteristics were investigated in this n-CBL UV-VLED.Furthermore, the efficiency of optimized structure was improved by 5 ~ 6 times compared to our reference.

View Article: PubMed Central - PubMed

Affiliation: Institute of Lighting and Energy Photonics, National Chiao Tung University, No.301, Gaofa 3rd Rd., Guiren Dist., Tainan City, 71150, Taiwan, yenchih.chiang@gmail.com.

ABSTRACT
For the purpose of light extraction and efficiency enhancement, the nitride-based ultraviolet vertical-injection light-emitting diodes (UV-VLEDs) with non-insulation current blocking layer (n-CBL) and optimized textured surface were fabricated. The optical and electrical characteristics were investigated in this n-CBL UV-VLED. Furthermore, the efficiency of optimized structure was improved by 5 ~ 6 times compared to our reference.

No MeSH data available.


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Light-current-voltage (L-I-V) characteristics of UV-VLEDs.
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Fig6: Light-current-voltage (L-I-V) characteristics of UV-VLEDs.

Mentions: Figure 6 illustrates the light-current-voltage (L-I-V) characteristics of these UV-VLEDs. With an injection current of 350 mA, the forward voltages were about 3.3 ~ 3.6 V for these UV-VLEDs. However, the forward voltage of UV-VLED-2 is decreased by 0.15 V from the value of C-VLED. We believe the reason is due to the damages from various etching processes. Great enhancement in output power can be observed from the UV-VLED-1, UV-VLED-2, and UV-VLED-3 when compared to the C-VLED result. Among these three cases, the UV-VLED-2 posts the best increment, and this great output power improvement (approximately 522%) could be mainly attributed to the n-CBL and textured surface. From cross-examination among our samples, different enhancement mechanisms can be identified comparatively. Assuming the epitaxial qualities of these samples are the same, the different fabrication processes distinguished the performances of the chips. First, between the C-VLED and UV-VLED-3, the only difference is the insertion of the n-CBL layer, and the power enhancement is 214% at 350 mA. Second, among the three samples of UV-VLED-1, UV-VLED-2, and UV-VLED-3, the only difference among them is the surface texture and thus the light extraction efficiency. The L-I comparison shows 98% and 61% of increase between UV-VLED-1 vs. UV-VLED-3 and between UV-VLED-2 vs. UV-VLED-3, respectively. Combining these two effects (n-CBL and texture), the overall enhancement factor is calculated as [(1 + 98%) × (1 + 214%) - 1] = 521%, which is close to the observed value between UV-VLED-2 and C-VLED (522%). The near-field images of these UV-VLEDs are shown in Figure 7. It can be seen that the light emission is more uniform in the UV-VLED-2 than that of the C-VLED. Between C-VLED and UV-VLED-3, the uniformity improves greatly due to the introduction of the n-CBL which can distribute current more evenly and avoid current crowding.Figure 6


Enhanced performance of nitride-based ultraviolet vertical-injection light-emitting diodes by non-insulation current blocking layer and textured surface.

Chiang YC, Lin BC, Chen KJ, Lin CC, Lee PT, Kuo HC - Nanoscale Res Lett (2014)

Light-current-voltage (L-I-V) characteristics of UV-VLEDs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493838&req=5

Fig6: Light-current-voltage (L-I-V) characteristics of UV-VLEDs.
Mentions: Figure 6 illustrates the light-current-voltage (L-I-V) characteristics of these UV-VLEDs. With an injection current of 350 mA, the forward voltages were about 3.3 ~ 3.6 V for these UV-VLEDs. However, the forward voltage of UV-VLED-2 is decreased by 0.15 V from the value of C-VLED. We believe the reason is due to the damages from various etching processes. Great enhancement in output power can be observed from the UV-VLED-1, UV-VLED-2, and UV-VLED-3 when compared to the C-VLED result. Among these three cases, the UV-VLED-2 posts the best increment, and this great output power improvement (approximately 522%) could be mainly attributed to the n-CBL and textured surface. From cross-examination among our samples, different enhancement mechanisms can be identified comparatively. Assuming the epitaxial qualities of these samples are the same, the different fabrication processes distinguished the performances of the chips. First, between the C-VLED and UV-VLED-3, the only difference is the insertion of the n-CBL layer, and the power enhancement is 214% at 350 mA. Second, among the three samples of UV-VLED-1, UV-VLED-2, and UV-VLED-3, the only difference among them is the surface texture and thus the light extraction efficiency. The L-I comparison shows 98% and 61% of increase between UV-VLED-1 vs. UV-VLED-3 and between UV-VLED-2 vs. UV-VLED-3, respectively. Combining these two effects (n-CBL and texture), the overall enhancement factor is calculated as [(1 + 98%) × (1 + 214%) - 1] = 521%, which is close to the observed value between UV-VLED-2 and C-VLED (522%). The near-field images of these UV-VLEDs are shown in Figure 7. It can be seen that the light emission is more uniform in the UV-VLED-2 than that of the C-VLED. Between C-VLED and UV-VLED-3, the uniformity improves greatly due to the introduction of the n-CBL which can distribute current more evenly and avoid current crowding.Figure 6

Bottom Line: For the purpose of light extraction and efficiency enhancement, the nitride-based ultraviolet vertical-injection light-emitting diodes (UV-VLEDs) with non-insulation current blocking layer (n-CBL) and optimized textured surface were fabricated.The optical and electrical characteristics were investigated in this n-CBL UV-VLED.Furthermore, the efficiency of optimized structure was improved by 5 ~ 6 times compared to our reference.

View Article: PubMed Central - PubMed

Affiliation: Institute of Lighting and Energy Photonics, National Chiao Tung University, No.301, Gaofa 3rd Rd., Guiren Dist., Tainan City, 71150, Taiwan, yenchih.chiang@gmail.com.

ABSTRACT
For the purpose of light extraction and efficiency enhancement, the nitride-based ultraviolet vertical-injection light-emitting diodes (UV-VLEDs) with non-insulation current blocking layer (n-CBL) and optimized textured surface were fabricated. The optical and electrical characteristics were investigated in this n-CBL UV-VLED. Furthermore, the efficiency of optimized structure was improved by 5 ~ 6 times compared to our reference.

No MeSH data available.


Related in: MedlinePlus