Characteristics comparison between GaN epilayers grown on patterned and unpatterned sapphire substrate (0 0 0 1)

Song, Jae Chul; Lee, Seon Ho; Lee, In Hwan; Seol, Kyeong Won; Santhakumar, Kannappan; Lee, Cheul Ro

doi:10.1016/j.jcrysgro.2007.08.030

Cited by 48 publications

(20 citation statements)

References 9 publications

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“…It originates from the recombination of excitons near the band-edge. The strong yellow emission peak corresponding to 560 nm is related to defects [27]. The obvious Fabry-Perot interference from the PL spectrum is observed due to a mirror-like thin film of GaN on sapphire substrate [28].…”

Section: Resultsmentioning

confidence: 94%

Fabrication and Characterization of GaN/Polymer Composite p-n Junction with PEDOT Nanoparticle Interface Layer

et al. 2011

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A heavily Si-doped GaN/polymer hybrid structure with p-type poly(3,4-ethylene-dioxythiophene):beta-1,3--glucan (PEDOT nanoparticle) interface layer has been fabricated. The Si-doped GaN thin film with carrier concentration of 1 × 10 19 cm −3 was grown by metal-organic chemical vapor deposition. The PEDOT nanoparticle with various sizes ranging from 60 to 120 nm was synthesized via a miniemulsion polymerization process. The electrical conductivity of the PEDOT nanoparticle is less than 1.2 S/cm. The current-voltage (I-V ) characteristic of the hybrid structure shows diode-like behavior. The I-V characteristic was examined in the framework of the thermionic emission model. The ideality factor of the structure without PEDOT nanoparticle interface layer is 12.9. However, the ideality factor of the hybrid structure with PEDOT nanoparticle interface layer is obtained as 1.9. The value of ideality factor is dramatically decreased by inserting the PEDOT nanoparticle interface layer.

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Section: Resultsmentioning

confidence: 94%

Fabrication and Characterization of GaN/Polymer Composite p-n Junction with PEDOT Nanoparticle Interface Layer

et al. 2011

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“…At the lower growth time, GaN grew as separate islands on the lens region and on the trench region, whereas the vertical growth takes place on the lens region, vertical and lateral growth GaN extending from the side walls of the pattern is on the trench region. The islands start to coalesce at the trench part with increasing the growth time [69]. Although the surface of this particular sample was flat, there exists a gap at the coalescence boundaries.…”

Section: The Patterning Of Sapphire Substratementioning

confidence: 84%

“…As the growth time increases, the GaN layer on the trench part grew separately covering the GaN pyramids during lateral growth, which led to TD bending toward GaN hexagonal pyramid [69]. Therefore, the TD density in the GaN epilayers can be effectively reduced.…”

Section: The Patterning Of Sapphire Substratementioning

confidence: 99%

Lowering the density of dislocations in heteroepitaxial III-nitride layers: Effect of sapphire substrate treatment (review)

Parphenyuk¹

2016

Semicond. Phys. Quantum Electron. Optoelectron.

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Abstract. In this paper, different methods for lowering the dislocation density such as incorporation of the buffer layers, substrate patterning and nitridation, silan-ammonia treatment are reviewed and compared. Advantages and limitations of these methods as well as a specific mechanism to reduce the dislocation amount are discussed. Usually, high densities of threading dislocations within the range 10 10 …10 11 cm -2 are present in typical thin nitride films that are directly grown on sapphire substrate. Using these methods for substrate preparation, the density of dislocations can be reduced to the value 1·10 7 cm -2. An important process that enables to obtain the high-quality GaN layers with the low dislocation density is patterning the sapphire substrate. The dislocation density of these substrates depends on the pattern shape and orientation of patterned strips on cplane sapphire. Layers of GaN grown on a cone-shaped pattern have the lowest dislocation density. In addition, patterning the sapphire substrate increases the external quantum efficiency of radiative structures and reduces the mechanical stresses in the nitride layers.

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“…It is well known that the near band-edge luminescence is very sensitive to the defects such as the TD density. Therefore, it is suggested that the trench region on the CCPSS has a lower defect density compared to that of the CC region due to the lateral growth which leads to a decrease of the TD density [20]. Also, this lateral growth mode can be understood from NSOM image and locally PL spectra which show the high brightness with strong peak intensity in trench regions due to full coalescence and less TD compared to over the CC region.…”

Section: Contributedmentioning

confidence: 98%

Characteristics of GaN‐based light emitting diode grown on circular convex patterned sapphire substrate

Lee

Jeong

et al. 2009

Phys. Status Solidi (c)

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We report the characteristics of GaN‐based light‐emitting diode (LED) grown on a circular convex patterned sapphire substrate (CCPSS) and conventional LEDs on a non‐patterned sapphire substrate (PSS) by metal‐organic chemical vapor deposition. A near field scanning optical microscope (NSOM) and micro Raman spectroscopy were employed to investigate the crystalline properties. In NSOM image and spectra of LED on CCPSS, an improved crystalline quality with emission fluctuation feature on the trench region was obtained. However, stress relaxation in this trench region was not achieved due to the presence of voids, indicating a stress concentration at the coalescence region. Compared to conventional LED on non‐PSS, increased internal quantum efficiency (IQE) (41.8%) and reduced leakage currents (40 nA at ‐10 V) were observed in the LED fabricated on CCPSS. The light output power of the LED on CCPSS was approximately two times higher than that of a conventional LED. This enhancement of output power is contributed to increase of IQE and the effective suppression of leakage current by reduction of dislocation density, as well as enhanced light scattering via the circular convex facets. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Characteristics comparison between GaN epilayers grown on patterned and unpatterned sapphire substrate (0 0 0 1)

Cited by 48 publications

References 9 publications

Fabrication and Characterization of GaN/Polymer Composite p-n Junction with PEDOT Nanoparticle Interface Layer

Fabrication and Characterization of GaN/Polymer Composite p-n Junction with PEDOT Nanoparticle Interface Layer

Lowering the density of dislocations in heteroepitaxial III-nitride layers: Effect of sapphire substrate treatment (review)

Characteristics of GaN‐based light emitting diode grown on circular convex patterned sapphire substrate

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