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Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs.

Shih HY, Shiojiri M, Chen CH, Yu SF, Ko CT, Yang JR, Lin RM, Chen MJ - Sci Rep (2015)

Bottom Line: Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition.This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2).In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.

ABSTRACT
High threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition. This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2). In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.

No MeSH data available.


Related in: MedlinePlus

Optical performances of the InGaN/GaN LEDs.(a) EL intensity as a function of injection current from 1 to 400 mA of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The inset represents a room-temperature EL spectrum of the LED grown on the ALD compliant BL. (b) The normalized EQE as a function of the injected current of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL.
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f8: Optical performances of the InGaN/GaN LEDs.(a) EL intensity as a function of injection current from 1 to 400 mA of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The inset represents a room-temperature EL spectrum of the LED grown on the ALD compliant BL. (b) The normalized EQE as a function of the injected current of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL.

Mentions: Figure 7(a,b) display the current vs. voltage (I–V) curves (in linear and semi-log scale, respectively), revealing the electrical characteristics of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The forward voltages at the input current of 350 mA are found to be 4.149 and 4.151 V for the LEDs on the ALD compliant BL and MOCVD NL, respectively. The inset in Fig. 7(a) shows that the leakage currents at −10 V are approximately the same in both of the LEDs. Figure 8(a) presents the electroluminescence (EL) intensity as a function of the injection current of both the InGaN/GaN LEDs. The LED grown on the ALD compliant BL exhibited greater light emission efficiency, which could be attributed to the suppressed nonradiative recombination by the reduced TD density. The inset in Fig. 8(a) shows the EL spectrum of the LED grown on the ALD compliant BL, with a center peak at 450 nm originating from the InGaN/GaN MQWs. Table S1 in the Supplementary Information summarizes the electrical and optical properties of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The reduced TD density of 2.2 × 105 cm−2 due to the ALD compliant BL is responsible for the higher light emission efficiency in the InGaN/GaN LED.


Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs.

Shih HY, Shiojiri M, Chen CH, Yu SF, Ko CT, Yang JR, Lin RM, Chen MJ - Sci Rep (2015)

Optical performances of the InGaN/GaN LEDs.(a) EL intensity as a function of injection current from 1 to 400 mA of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The inset represents a room-temperature EL spectrum of the LED grown on the ALD compliant BL. (b) The normalized EQE as a function of the injected current of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556983&req=5

f8: Optical performances of the InGaN/GaN LEDs.(a) EL intensity as a function of injection current from 1 to 400 mA of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The inset represents a room-temperature EL spectrum of the LED grown on the ALD compliant BL. (b) The normalized EQE as a function of the injected current of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL.
Mentions: Figure 7(a,b) display the current vs. voltage (I–V) curves (in linear and semi-log scale, respectively), revealing the electrical characteristics of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The forward voltages at the input current of 350 mA are found to be 4.149 and 4.151 V for the LEDs on the ALD compliant BL and MOCVD NL, respectively. The inset in Fig. 7(a) shows that the leakage currents at −10 V are approximately the same in both of the LEDs. Figure 8(a) presents the electroluminescence (EL) intensity as a function of the injection current of both the InGaN/GaN LEDs. The LED grown on the ALD compliant BL exhibited greater light emission efficiency, which could be attributed to the suppressed nonradiative recombination by the reduced TD density. The inset in Fig. 8(a) shows the EL spectrum of the LED grown on the ALD compliant BL, with a center peak at 450 nm originating from the InGaN/GaN MQWs. Table S1 in the Supplementary Information summarizes the electrical and optical properties of the InGaN/GaN LEDs grown on the ALD compliant BL and MOCVD NL. The reduced TD density of 2.2 × 105 cm−2 due to the ALD compliant BL is responsible for the higher light emission efficiency in the InGaN/GaN LED.

Bottom Line: Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition.This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2).In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.

ABSTRACT
High threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition. This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2). In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.

No MeSH data available.


Related in: MedlinePlus