Control of silica cap properties by oxygen plasma treatment for single-cap selective impurity free vacancy disordering

Helmy, Amr S.; Murad, S. K.; Bryce, A.C.; Aitchison, J. S.; Marsh, J.H.; Hicks, S. E.; Wilkinson, C. D. W.

doi:10.1063/1.123106

Cited by 28 publications

(13 citation statements)

References 17 publications

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“…2 Previous works reported that porosity in the dielectric cap determine the wavelength shifts of the QW structure. 3,4 The sol-gel process is a commercially promising technology compared with other thin film technologies, with advantages such as low cost, ease of doping variation, and high homogeneity of multicomponent oxide films. It is well known that sol-gel derived films are porous under moderate heat-treatment temperatures.…”

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confidence: 99%

Sintering and Porosity Control of (x)GeO[sub 2]:(1−x)SiO[sub 2] Sol-Gel Derived Films for Optoelectronic Applications

Djie

Pita

et al. 2004

Electrochem. Solid-State Lett.

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Sol-gel derived GeO 2 -doped silica thin films (x)GeO 2 :(1Ϫx)SiO 2 with x ϭ 5 to 40 mol % were studied for heat-treatments from 500 to 1000°C. In the conventional single component sol-gel process, temperature is the process parameter that controls the porosity of the film. However, our results revealed that by varying Ge-doping, the film porosity, as determined by spectroscopic ellipsometry, can be tailored across the temperature range studied. The mechanisms contributing to the quasi-linear compositionaldependent porosity are Ge precursor chemistry and viscous sintering. This technique can be versatile in applications such as III-V optoelectronic devices realized by quantum-well intermixing.In optoelectronics, porous dielectric materials have been used as a mean to promote quantum well intermixing ͑QWI͒ to tune the operating wavelength of the different integrated photonic devices via impurity-free vacancy diffusion ͑IFVD͒. 1 These dielectric materials are used in a form of capping layer that is deposited on top of a given quantum well ͑QW͒ structure. It has been found that group III and/or V elements out-diffuse into the dielectric cap layer creating vacancies in the lattice structure of the alloy. Such vacancies propagate into the QW region and activate interdiffusion of the different elements across the quantum well and its barrier leading to a change in the bandgap profile. 2 Previous works reported that porosity in the dielectric cap determine the wavelength shifts of the QW structure. 3,4 The sol-gel process is a commercially promising technology compared with other thin film technologies, with advantages such as low cost, ease of doping variation, and high homogeneity of multicomponent oxide films. It is well known that sol-gel derived films are porous under moderate heat-treatment temperatures. The porosity of the films can be controlled by subjecting the films to different heat-treatments. For certain applications, there can be various constraints on the allowable thermal treatment that can be performed on the film; hence, other parameters are desired to control the porosity of the films. For example, to promote QWI, Ga-As based QW structures can withstand annealing temperatures up to ϳ900°C without deterioration in optical performance; while the more prominent In-P based QW structures can only tolerate up to 600°C due to its poor thermal stability. 5 In the light of photonic integration, where multiple bandgaps across a single substrate are required, 6 controlling porosity in the sol-gel dielectric caps by only annealing temperature would be impractical.Alternatively, the effects of doped-SiO 2 caps ͑i.e., phosphorus 7-9 ͒ have been demonstrated with bandgap tuning results attributed to the different physical properties of the cap, namely, the film porosity. However, the doping level of phosphorous has been restricted to less than 10 mol % as the material otherwise becomes hygroscopic.In this paper, we show that, by increasing the amount of GeO 2 content in our binary GeO 2 :SiO 2 sol-gel material, the...

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confidence: 99%

Sintering and Porosity Control of (x)GeO[sub 2]:(1−x)SiO[sub 2] Sol-Gel Derived Films for Optoelectronic Applications

Djie

Pita

et al. 2004

Electrochem. Solid-State Lett.

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“…The properties of SiO 2 may have a great effect on enhancing QW intermixing. 16 The spin-on silica film can reduce the threshold temperature at which significant QW intermixing takes place. From previous studies, it is clear that, compared to a bare surface, the oxidation of GaAs surface can enhance the QW intermixing.…”

Section: Qw Intermixng Resultsmentioning

confidence: 99%

Multi-wavelength lasers fabricated by an Al layer controlled quantum well intermixing technology

Teng

Chua

Huang

et al. 2000

Journal of Applied Physics

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Articles you may be interested inSiNx-induced intermixing in AlInGaAs/InP quantum well through interdiffusion of group III atoms J. Appl. Phys. 112, 093109 (2012); 10.1063/1.4764856Photoreflectance investigations of quantum well intermixing processes in compressively strained In Ga As P ∕ In Ga As P quantum well laser structures emitting at 1.55 μ m Enhanced band-gap blueshift due to group V intermixing in InGaAsP multiple quantum well laser structures induced by low temperature grown InPWe report that the shift in the band gap of Al 0.3 Ga 0.7 As/GaAs quantum well structures can be precisely controlled by an Al layer buried between a spin-on silica film and a wet-oxidized GaAs surface. The blueshift in wavelength of the Al 0.3 Ga 0.7 As/GaAs quantum well photoluminescence ͑PL͒ depends linearly on the thickness of the buried Al layer. By changing the Al layer thickness, the PL peak wavelength can be tuned from 7870 Å for the as-grown sample to 7300 and 7050 Å after 20 and 45 s rapid thermal annealing at 850°C, respectively. Applying this technology, Al layers with different thickness, i.e., no Al, 200 and 300 Å thick, were applied to the oxidized GaAs surface in three adjacent regions with 200 m spacing on a quantum well laser structure sample. Three wavelength lasers were successfully fabricated in a single chip by a one step rapid thermal annealing. All the lasers have similar threshold current and slope efficiency.

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“…Selective-area QWI is a very promising technique for the realization of monolithically integrated devices. To date, a number of QWI techniques have been reported, including impurityinduced disordering (Ooi et al 1994), impurity-free vacancy-induced disordering (IFVD) (Helmy et al 1999), ion implantation-induced inter-diffusion (Wan et al 1997), and several laser-induced disordering processes (Ralston et al 1987). IFVD is usually implemented by the deposition of a dielectric film coating followed by rapid thermal annealing (RTA).…”

Section: Introductionmentioning

confidence: 98%

Monolithically Integrated All-optical Switch using Quantum Well Intermixing

Nah

LiKamWa

2006

Opt Quant Electron

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Control of silica cap properties by oxygen plasma treatment for single-cap selective impurity free vacancy disordering

Cited by 28 publications

References 17 publications

Sintering and Porosity Control of (x)GeO[sub 2]:(1−x)SiO[sub 2] Sol-Gel Derived Films for Optoelectronic Applications

Sintering and Porosity Control of (x)GeO[sub 2]:(1−x)SiO[sub 2] Sol-Gel Derived Films for Optoelectronic Applications

Multi-wavelength lasers fabricated by an Al layer controlled quantum well intermixing technology

Monolithically Integrated All-optical Switch using Quantum Well Intermixing

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