Nanopore morphology in porous GaN template and its effect on the LEDs emission

Soh, C. B.; Tay, Chuan Beng; Tan, Rayson J. N.; Vajpeyi, A. P.; Seetoh, Ian P.; Ansah-Antwi, Kwadwo Konadu; Chua, Soo Jin

doi:10.1088/0022-3727/46/36/365102

Cited by 39 publications

(42 citation statements)

References 34 publications

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“…To date, active exploration on porous III‐nitrides semiconductors have been restricted to porous GaN, wherein a significant improvement in terms of structural and optical properties in overgrown layers on the porous GaN template has been reported . A reduction in dislocation density as well as an enhancement in electroluminescence intensity and quantum dot emission were achieved for a strain‐relaxed GaN film and In x Ga x N layer grown on the porous GaN template for LED applications. An enhancement in photoluminescence (PL) intensity was on the other hand obtained for Al y Ga y N film grown on porous GaN due to a compressive strain relaxation .…”

Section: Introductionmentioning

confidence: 99%

Porous Quaternary Al_0.1In_0.1Ga_0.8N Film Formation via Photoelectrochemical Etching in HF:C₂H₅OH Electrolyte

et al. 2016

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Pore formation in AlInGaN films using photoelectrochemical etching in different volume ratios of hydrofluoric acid:ethanol solution (1:1, 1:2, 1:3, and 1:4) has been investigated structurally, morphologically, and optically. A significant increase in root mean square roughness and photoluminescence intensity in AlInGaN film etched in 1:1 solution has yielded the highest pore density and the largest average pore size in the film. Moreover, the acquisition of the lowest total dislocation density as well as the largest in-plane biaxial stress relaxation in the film suggested potential use of the porous film as a template to grow subsequent layers for development of light-emitting diodes.

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Section: Introductionmentioning

confidence: 99%

Porous Quaternary Al_0.1In_0.1Ga_0.8N Film Formation via Photoelectrochemical Etching in HF:C₂H₅OH Electrolyte

et al. 2016

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“…Many previous studies on porous GaN have reported that the pore density and etching profile strongly correlated with dislocations of GaN crystal. 20,21 In these reports, hetero-epitaxial GaN films grown on sapphire substrates were used, where the TDD of GaN crystal was typically 10 9 to 10 10 cm −2 . In the case of such high TDD, the positive holes supplied to EC reactions would be strongly affected by the dislocations, which acted as recombination centers.…”

Section: Resultsmentioning

confidence: 99%

Precise Structural Control of GaN Porous Nanostructures Utilizing Anisotropic Electrochemical and Chemical Etching for the Optical and Photoelectrochemical Applications

Kumazaki

Matsumoto

Sato

2017

J. Electrochem. Soc.

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A low-damaged wet process utilizing electrochemical (EC) etching and subsequent chemical etching has been developed for the fabrication of GaN porous structures. Superior controllability in depth and diameter could be obtained by achieving anisotropic nature of the vertical direction to the substrate by EC etching and horizontal direction by tetramethylammonium hydroxide (TMAH) etching, respectively. The optical and photoelectrochemical properties of GaN porous structures were very sensitive to the structural properties. Photoreflectance measurement revealed that porous sample had an effective refractive index that could be controlled by TMAH etching time. In photoelectrochemical measurement, the incident-photon-to-current conversion efficiency (IPCE) was dramatically enhanced to as high as 91% by the formation of porous structures. A series of experimental results were consistently explained by the change of thickness of pore wall and width of space charge region. Gallium nitride (GaN) and its alloys are getting much attention as building block materials for electrochemical (EC) energy conversion systems such as chemical sensors, water splitting, and artificial photosynthesis because of their attractive features including superior chemical stability, direct transition, and widely tunable bandgap by alloying.1-4 Among the various techniques for improving their conversion efficiency, porosification utilizing EC reactions is one of the most powerful because a high-density array of pores exhibits high specific surface area, low reflectance, and high absorptance properties. 5,6 In addition, this technique is performed at room temperature and does not require any complicated process such as lithography, indicating lower damage and higher productivity than other nanostructure fabrication techniques such as reactive ion etching and selective-area growth. 7-10Many reports involving porosification use photo-assisted EC etching utilizing charge carriers generated by band-edge absorption. 11-14Our group has also succeeded in forming GaN porous nanostructures by photo-assisted EC etching and found the energy-conversion efficiency to be enhanced compared with the planar substrate. 15 However, the pore depth could not be controlled linearly by etching time, resulting in difficulty with forming pores deeper than a micro-meter. This was because charge carriers, most of which were generated near the top surface, were expended preferentially in the lateral etching of pore walls that appeared on the top surface. Such insufficient anisotropic nature makes it difficult to improve structural controllability and form pores deeper than a micro-meter.In this study, we aimed to develop anisotropic EC etching by utilizing charge carriers generated by the avalanche effect as a porosification process. We also investigated a combination of EC etching and subsequent wet chemical etching to further improve the structural controllability. Optical characterization such as photoluminescence (PL), photoreflectance, and photoelectrochemical measure...

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“…In essence, beneficial effects brought by porous GaN [30][31][32][33] and porous In y Ga 1-y N [34][35] in the aspects of an enhancement in PL intensity, an improvement in internal quantum efficiency and light extraction efficiency, as well as a relaxation of compressive stress with decreased dislocation density have provoked considerable interest on formation of pore geometry in the quaternary Al x In y Ga 1-x-y N layer. Moreover, the aforementioned benefits of porous formation revealed significance of the porous III-nitrides semiconductors as templates for growth of subsequent overgrown layers.…”

Section: A N U S C R I P Tmentioning

confidence: 99%

Alteration of structural and optical properties in quaternary Al0.1In0.1Ga0.8N films using ultraviolet assisted photo-electrochemical etching route

Lim

Quah

Hassan

et al. 2015

Journal of Alloys and Compounds

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Nanopore morphology in porous GaN template and its effect on the LEDs emission

Cited by 39 publications

References 34 publications

Porous Quaternary Al_0.1In_0.1Ga_0.8N Film Formation via Photoelectrochemical Etching in HF:C₂H₅OH Electrolyte

Porous Quaternary Al_0.1In_0.1Ga_0.8N Film Formation via Photoelectrochemical Etching in HF:C₂H₅OH Electrolyte

Precise Structural Control of GaN Porous Nanostructures Utilizing Anisotropic Electrochemical and Chemical Etching for the Optical and Photoelectrochemical Applications

Alteration of structural and optical properties in quaternary Al0.1In0.1Ga0.8N films using ultraviolet assisted photo-electrochemical etching route

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Nanopore morphology in porous GaN template and its effect on the LEDs emission

Cited by 39 publications

References 34 publications

Porous Quaternary Al0.1In0.1Ga0.8N Film Formation via Photoelectrochemical Etching in HF:C2H5OH Electrolyte

Porous Quaternary Al0.1In0.1Ga0.8N Film Formation via Photoelectrochemical Etching in HF:C2H5OH Electrolyte

Precise Structural Control of GaN Porous Nanostructures Utilizing Anisotropic Electrochemical and Chemical Etching for the Optical and Photoelectrochemical Applications

Alteration of structural and optical properties in quaternary Al0.1In0.1Ga0.8N films using ultraviolet assisted photo-electrochemical etching route

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Porous Quaternary Al_0.1In_0.1Ga_0.8N Film Formation via Photoelectrochemical Etching in HF:C₂H₅OH Electrolyte

Porous Quaternary Al_0.1In_0.1Ga_0.8N Film Formation via Photoelectrochemical Etching in HF:C₂H₅OH Electrolyte