A new method of reducing dislocation density in GaN layer grown on sapphire substrate by MOVPE

Sakai, Shiro; Wang, T; Morishima, Y.; Naoi, Yoshiki

doi:10.1016/s0022-0248(00)00709-0

Cited by 117 publications

(78 citation statements)

References 5 publications

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“…The use of in-situ SiN x interlayer has proven to be an effective technique in defect reduction in conventional c-plane GaN. [11][12][13] In this letter, we report on the use of insitu SiN x nanomask for defect reduction in a-plane GaN films. The simplicity of an in-situ defect reduction growth method is highly attractive.…”

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confidence: 98%

Defect reduction in nonpolar a-plane GaN films using in situ SiNx nanomask

Chakraborty

Kim

et al. 2006

Applied Physics Letters

112

106

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We report on the use of in-situ SiNx nanomask for defect reduction in nonpolar a-plane GaN films, grown by metal-organic chemical vapor deposition. High-resolution x-ray diffraction analysis revealed that there was a monotonic reduction in the full width at half maximum, both on-axis and off-axis, with the increase in the SiNx thickness. Atomic force microscopy images revealed a significant decrease in the root-mean-square roughness and the density of submicron pits. Cross-section and plan-view transmission electron microscopy on the samples showed that the stacking fault density decreased from 8×105to3×105cm−1 and threading dislocation density decreased from 8×1010to9×109cm−2. Room temperature photoluminescence measurement revealed that the band-edge emission intensity increased with the insertion of the SiNx layer, which suggests reduction in the nonradiative recombination centers.

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confidence: 98%

Defect reduction in nonpolar a-plane GaN films using in situ SiNx nanomask

Chakraborty

Kim

et al. 2006

Applied Physics Letters

112

106

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“…S. Sakai (S. Sakai et al, 2000) also reported threading dislocation reduction in GaN with Si x N y layer by metalorganic chemical vapor deposition. The threading dislocation density is dramatically decreased from 7×10 8 cm -2 in the conventional method to almost invisible in the observing area of the TEM.…”

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confidence: 98%

“…The schematic illustration of the proposed mechanism GaN in SiN buffer layer. After ref (Sakai et al, 2000). • GaN film grown on a 15-nmthickbuffer grown at 525°C has a smooth surface (rms=0.56nm).…”

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confidence: 99%

Gallium Nitride: An Overview of Structural Defects

Yam¹,

Low²,

Oh³

et al. 2011

Optoelectronics - Materials and Techniques

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“…4 In situ deposition of a natural SiN x nano mask for lateral growth has been utilized to reduce dislocation density in GaN on sapphire. 5,6 It is reported that using a SiN x interlayer in GaN grown on Si (111) substrates cannot only reduce dislocations but also decrease thermal stress on GaN.7 Similar to the mechanism of epitaxial lateral overgrowth, the in-situ SiN x nanomask results in nucleation of nano size GaN islands with the {1-101} facets, which bend the threading dislocations from the <0001> directions toward the <1-100> directions.8 However, new dislocations are generated in the regions where islands coalesce. …”

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confidence: 99%

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confidence: 99%

A Self-Assembled Double-Island Buffer Structure for Improving GaN-Based Materials Grown on Si Substrates

Liu

Cheng

Yeh

et al. 2014

ECS J. Solid State Sci. Technol.

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This paper reports a new method to reduce threading dislocation density in GaN epilayers grown on (111) Si substrates by metalorganic chemical vapor deposition. This method utilizes an in-situ SiN x mask to produce a self-assembled double-island structure, which effectively reduces threading dislocation density from 9.6 × 10 9 cm −2 to 2.6 × 10 9 cm −2 without using any lithographic and regrowth processes. InGaN light-emitting diodes fabricated on the double-island buffer layer exhibit nearly 20% improvement on the optical output power as well as less energy localization effect, compared to those without the double-island buffer layer. Growing GaN on silicon (111) substrates has been regarded as a promising approach to achieving low-cost GaN-based light-emitting diodes and power devices. To grow a high quality GaN epitaxial layer on silicon substrates, it is necessary to overcome the cracking of GaN layer, which originates from the large difference in the thermal expansion coefficient between GaN and silicon.1 The other key issue to resolve is the high dislocation density of up to 10 10 cmin GaN due to the their 17% lattice constant mismatch. So far, there have been several methods proposed to tackle the cracking and high dislocation density issues, such as multi-epitaxial-lateral-overgrowth (multi-ELO), 2 graded AlGaN insertion layer, 3 AlGaN/GaN superlattice, and patterned substrate. 4 In situ deposition of a natural SiN x nano mask for lateral growth has been utilized to reduce dislocation density in GaN on sapphire. 5,6 It is reported that using a SiN x interlayer in GaN grown on Si (111) substrates cannot only reduce dislocations but also decrease thermal stress on GaN.7 Similar to the mechanism of epitaxial lateral overgrowth, the in-situ SiN x nanomask results in nucleation of nano size GaN islands with the {1-101} facets, which bend the threading dislocations from the <0001> directions toward the <1-100> directions.8 However, new dislocations are generated in the regions where islands coalesce. 9In this study, we develop a new growth method, which is a selfassembled island growth method based on two layers of in-situ SiN x mask, to lower the dislocation density in GaN without any regrowth processes. InGaN/GaN light-emitting diodes (LEDs) with improved performance are demonstrated on Si substrates using the double-island structure. Sample PreparationAll the samples in this study were grown on 2" Si (111) substrates using metal-organic chemical vapor deposition (MOCVD). Before the epitaxial growth, the native oxide of silicon substrates was chemically removed in hydrofluoric acid. A reference sample without any island structure was grown on a conventional buffer layer, consisting of 60 nm AlN, 100 nm Al 0.2 Ga 0.8 N, and 500 nm un-doped GaN. The samples with a single-or a double-island structure were formed by depositing an in-situ SiN x mask on the conventional buffer layer between the Al 0.2 Ga 0.8 N and GaN layers. The double-island structure was formed by repeating the growth sequence once more after t...

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A new method of reducing dislocation density in GaN layer grown on sapphire substrate by MOVPE

Cited by 117 publications

References 5 publications

Defect reduction in nonpolar a-plane GaN films using in situ SiNx nanomask

Defect reduction in nonpolar a-plane GaN films using in situ SiNx nanomask

Gallium Nitride: An Overview of Structural Defects

A Self-Assembled Double-Island Buffer Structure for Improving GaN-Based Materials Grown on Si Substrates

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