Free-standing, optically pumped, GaN∕InGaN microdisk lasers fabricated by photoelectrochemical etching

Haberer, Elaine D.; Sharma, Rajat; Meier, Cedrik; Stonas, A. R.; Nakamura, Shuji; DenBaars, Steven P.; Hu, Evelyn L.

doi:10.1063/1.1829167

Cited by 83 publications

(62 citation statements)

References 23 publications

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“…7,8 However, the superior optical confinement capabilities of GaN WGM microcavities are invariably weakened by optical leakage through its transparent sapphire substrate. Recently, GaN-based undercut two-dimensional (2D) WGM microdisk lasers fabricated through the removal of sacrificial layers embedded within the device structure by photoelectrochemical (PEC) or selective wet-etching [9][10][11] have been reported to effectively reduce such losses. Similar undercut microdisk structures have also been demonstrated by controlled wet-etch removal of the underlying Si substrate using GaN-on-Si materials.…”

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confidence: 99%

GaN hemispherical micro-cavities

Zhang

Cong

Wang

et al. 2016

Applied Physics Letters

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GaN-based micro-dome optical cavities supported on Si pedestals have been demonstrated by dry etching through gradually shrinking microspheres followed by wet-etch undercutting. Optically pumped whispering-gallery modes (WGMs) have been observed in the near-ultraviolet within the mushroom-like cavities, which do not support Fabry-Pérot resonances. The WGMs blue-shift monotonously as the excitation energies are around the lasing threshold. Concurrently, the mode-hopping effect is observed as the gain spectrum red-shifts under higher excitations. As the excitation energy density exceeds ∼15.1 mJ/cm2, amplified spontaneous emission followed by optical lasing is attained at room temperature, evident from a super-linear increase in emission intensity together with linewidth reduction to ∼0.7 nm for the dominant WGM. Optical behaviors within these WGM microcavities are further investigated using numerical computations and three-dimensional finite-difference time-domain simulations.

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confidence: 99%

GaN hemispherical micro-cavities

Zhang

Cong

Wang

et al. 2016

Applied Physics Letters

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“…However, due to the optical diffraction limit of the light source, the photolithography process can hardly reproduce the mask pattern with accuracy at sub-wavelength scales. More importantly, erosion of the photoresist structures during dry-etching induces imperfections to the circularity and sidewall roughness of the fabricated microdisks [28], as shown in Fig. 6a and b.…”

Section: Feature Articlementioning

confidence: 99%

Advances in III‐nitride semiconductor microdisk lasers

Zhang

et al. 2015

Physica Status Solidi (a)

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This paper reviews the recent progress in the design and fabrication strategies of III-nitride semiconductor microdisk lasers on sapphire or Si substrates. Involving more accurate lithography methods in the fabrication boosts quality factors (Q-factors) due to the improved optical confinement of whispering-gallery modes (WGMs) at the rim of the microdisks with smooth sidewalls and perfect circularity. Quantum dots (QDs) as gain medium within the microdisks are investigated and promising for the demonstration of microlasers with super-high Q-factors and ultra-low thresholds. And these QD-cavity systems are also facilitating the research of cavity quantum electrodynamics (QED) in the strong coupling regime and cavity-enhanced single photon emission (SPE) for quantum computing. In this paper, we also report successful fabrication of transferred GaN free-standing microdisks with InGaN quantum wells (QWs) on conductive substrates, which achieves a significant step forward to realize electrically pumped high-quality microdisk lasers on target substrates. Strategies of applying flexible transparent electrodes such as graphene and metallic nanowires are potential effective solutions for realizing current-injection of nitride-based microdisks.ß 2015 WILEYÀVCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Over past few decades, group IIInitride compound semiconductors have been extensively studied and have emerged as indispensable materials for a wide range of optoelectronic devices. With a wide and direct energy bandgap, emissions from III-nitride semiconductors can cover the wavelength range from deep ultraviolet to the near-infrared, making them ideal candidates for incoherent and coherent light sources [1][2][3][4]. Moreover, as epitaxial growth techniques of III-nitride materials become mature, high quality quantum structures such as quantum wells (QWs) and quantum dots (QDs) can be readily achieved, greatly improving the emission efficiency via quantum confinement of the carriers within a small active region so that the possibility of radiative recombination increases, serving as gain medium for highly efficient light emitters [5][6][7]. In addition, the high binding energies of excitons in these wide bandgap materials motivate the research on photon-exciton (or polariton) dynamics and its coherent state polariton lasing in microcavities [8][9][10][11]. In fact, the research of nitride-based microcavity lasers has attracted much attention in past decades for both physical insight of lasing mechanisms in both the weak and strong coupling regimes and their widespread applications [12]. Until now,

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“…This process was developed by Haberer et al [7] and further refined by Tamboli et al [4], who suggested that due to the polarisation inherent within c-plane nitrides, the sacrificial layer should consist of a super-lattice in order to modulate the band edge and ensure a homogenous distribution of photogenerated holes across the layer surface during the etch process. The growth of such heterostructures is in itself a challenge, due to the accumulated strain between the heterostructure layers, and potential strain relaxation, which can generate extra dislocations (in addition to those already present in the pseudo-substrate).…”

Section: Introductionmentioning

confidence: 99%

InGaN super-lattice growth for fabrication of quantum dot containing microdisks

El-Ella

Rol

Collins

et al. 2011

Journal of Crystal Growth

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A1. Critical stack thickness A1. Dislocations A3. Metalorganic vapour phase epitaxy B1. Nitrides B2. InGaN quantum dots B3. Microdisks a b s t r a c tMicrostructural characterisation of a heterostructure containing an In x Ga 1 À x N/In y Ga 1 À y N super-lattice sacrificial layer (SSL), an AlGaN etch stop layer and an InGaN quantum dot layer has been carried out. These structures are intended for photo-electrochemical etch mediated fabrication of undercut microdisks and were found to generate additional dislocations due to the additional strain energy imposed by the growth and inclusion of the InGaN quantum dot layer. Micro-photoluminescence was also carried out and showed the unexpected formation of quantum dots within the SSL. An equilibrium critical stack thickness model corresponding to the total thickness of the heterostructure that would favour the additional generation of dislocations was formulated through an energy-balance consideration. This correlated well with the experimental results and a prediction of the SSL indium composition for the full structure that would not lead to additional dislocation generation could thus be made.

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Free-standing, optically pumped, GaN∕InGaN microdisk lasers fabricated by photoelectrochemical etching

Cited by 83 publications

References 23 publications

GaN hemispherical micro-cavities

GaN hemispherical micro-cavities

Advances in III‐nitride semiconductor microdisk lasers

InGaN super-lattice growth for fabrication of quantum dot containing microdisks

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