Journal ArticleDOI
Nanopores in GaN by electrochemical anodization in hydrofluoric acid: Formation and mechanism
Danti Chen,Hongdi Xiao,Jung Han +2 more
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TLDR
In this paper, the use of hydrofluoric acid (HF) as an electrolyte in etching and porosifying GaN was reported, and it was shown that the formation of nanoporous structures is largely due to the local breakdown of the reverse-biased semiconductor junction.Abstract:
We report the use of hydrofluoric acid (HF) as an electrolyte in etching and porosifying GaN. HF is found to be effective in rendering a wide range of nanoporous morphology, from curved branches to highly parallel straight pores. Under suitable conditions, the porosification proceeds at a rate greater than 100 μm/min. To elucidate the etching mechanism, cyclic voltammetry is performed, together with a parametric mapping of electrolysis variables such as the doping of GaN, the concentration of HF electrolyte, and the anodization voltage. We demonstrate that the formation of nanoporous structures is largely due to the local breakdown of the reverse-biased semiconductor junction. A quantitative agreement between the estimated width of space-charge region and the observed variation in morphology lends support to a depletion layer model developed previously in the etching of porous-Si.read more
Citations
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Journal ArticleDOI
Mesoporous GaN for Photonic Engineering-Highly Reflective GaN Mirrors as an Example
Cheng Zhang,Sung Hyun Park,Danti Chen,Da Wei Lin,Wen Xiong,Hao-Chung Kuo,Chia-Feng Lin,Hui Cao,Jung Han +8 more
TL;DR: The meso-and microporous GaN can be considered a new form of GaN with unprecedented optical index tunability in epitaxial structures without compromising the structural and electrical properties as mentioned in this paper.
Journal ArticleDOI
High-Q, Low-Threshold Monolithic Perovskite Thin-Film Vertical-Cavity Lasers
TL;DR: A vertical-cavity surface-emitting perovskite laser is achieved using a microCavity configuration where CH3 NH3 PbI3 thin solid films are embedded within a custom GaN-based high-quality (Q-factor) resonator.
Journal ArticleDOI
Wide bandgap III-nitride nanomembranes for optoelectronic applications
TL;DR: The preparation of GaN NMs with a freestanding thickness between 90 to 300 nm is demonstrated and bright blue light emission from this heterostructure validates the concept of NM-based optoelectronics and points to potentials in flexible applications and heterogeneous integration.
Journal ArticleDOI
High reflectance membrane-based distributed Bragg reflectors for GaN photonics
Danti Chen,Jung Han +1 more
TL;DR: In this paper, a membrane-based GaN/air-gap DBR for blue/green light emitting devices is presented, where the formation of membrane DBRs relies on a recently discovered electrochemical procedure in which selective etch is achieved by adjusting the conductivity rather than chemical composition.
Journal ArticleDOI
Anodic Etching of n-GaN Epilayer into Porous GaN and Its Photoelectrochemical Properties
TL;DR: Porous n-GaN has been fabricated using electrochemical anodic etching in a 0.5 M H2SO4 solution in the dark for different biases (5.5-18.0 V) as mentioned in this paper.
References
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Journal ArticleDOI
Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers
TL;DR: In this paper, free standing Si quantum wires can be fabricated without the use of epitaxial deposition or lithography using electrochemical and chemical dissolution steps to define networks of isolated wires out of bulk wafers.
Journal ArticleDOI
Porous silicon formation: A quantum wire effect
Volker Lehmann,Ulrich Gösele +1 more
TL;DR: In this article, it was shown that a two-dimensional quantum confinement (quantum wire) in the very narrow walls between the pores not only explains the change in band gap energy but also may also explain the dissolution mechanism that leads to porous silicon formation.
Journal ArticleDOI
Self-organized formation of hexagonal pore arrays in anodic alumina
TL;DR: In this article, the conditions for the self-organized formation of ordered hexagonal structures in anodic alumina were investigated for both oxalic and sulfuric acid as an electrolyte.
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Porous silicon formation mechanisms
TL;DR: In this article, various models describing porous silicon formation are reviewed and the known electrochemical and morphological properties are discussed with the intention of unifying the different models into a comprehensive explanation for the formation of a porous structure in silicon.
Journal ArticleDOI
Formation Mechanism and Properties of Electrochemically Etched Trenches in n‐Type Silicon
Volker Lehmann,Helmut Föll +1 more
TL;DR: In this article, the spontaneous trench formation in n-type silicon immersed in hydrofluoric acid under anodic bias is demonstrated and the resulting microstructures are characterized and explained by a model which takes into account the conditions of the space charge region the minority carrier current and the crystal orientation.