Electrical Characterization of Impurity-Free Disordered p-Type GaAs

Deenapanray, Prakash; Coleman, Victoria A.; Jagadish, Chennupati

doi:10.1149/1.1543335

Cited by 15 publications

(18 citation statements)

References 30 publications

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“…The In 0.5 Ga 0.5 As quantum dots were grown at 550°C before the temperature was ramped up to 650°C for the growth of a 2000 Å cap of GaAs above the dot layer(s). 3 The porosity affects the solubility of the Ga atoms in the layer. Two types of stacked dot structures were investigated, one set included a thin GaP layer between each dot layer to provide strain compensation.…”

Section: Methodsmentioning

confidence: 99%

Impurity free vacancy disordering of InGaAs quantum dots

Lever¹,

Tan²,

Jagadish³

2004

Journal of Applied Physics

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Influence of dielectric deposition parameters on the In 0.2 Ga 0.8 As / GaAs quantum well intermixing by impurity-free vacancy disordering Dependence of band gap energy shift of In 0.2 Ga 0.8 As/GaAs multiple quantum well structures by impurity-free vacancy disordering on stoichiometry of SiO x and SiN x capping layersThe effect of thermal interdiffusion on In͑Ga͒As/ GaAs quantum dot structures is very significant, due to the large strain and high concentration of indium within the dots. The traditional high temperature annealing conditions used in impurity free vacancy disordering of quantum wells cannot be used for quantum dots, as the dots can be destroyed at these temperatures. However, additional shifts due to capping layers can be achieved at low annealing temperatures. Spin-on-glass, plasma enhanced chemical vapor deposited SiO 2 , Si 3 N 4 , and electron-beam evaporated TiO 2 layers are used to both enhance and suppress the interdiffusion in single and stacked quantum dot structures. After annealing at only 750°C the different cappings enable a shift in band gap energy of 100 meV to be obtained across the sample.

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Section: Methodsmentioning

confidence: 99%

Impurity free vacancy disordering of InGaAs quantum dots

Lever¹,

Tan²,

Jagadish³

2004

Journal of Applied Physics

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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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“…The intermixing occurs as annealed SiO x adsorbs Ga from the semiconductor interface and the annealing drives the Ga vacancies down in the structure resulting in the migration of Al atoms from the AlGaAs barrier layer into the QW causing a blue shift of the characteristic wavelength of the QW. Moreover, following Deenapanray et al 9,10 the quality of the SiO x layers is essential to allow the adsorption of Ga atoms and hence the intermixing: the more porous the SiO x layer, the higher the intermixing effect. The quality of the PECVD SiO x used has been tested, and it is found that a BHF solution removes the SiO x layer in a few seconds.…”

Section: Discussionmentioning

confidence: 99%

Enhancement of p-GaN Conductivity Using PECVD SiO[sub x]

Karouta

Kappers

Krämer

et al. 2005

Electrochem. Solid-State Lett.

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A technique to enhance the hole concentration in activated Mg-doped p-type GaN epitaxial layers is described. The method consists of depositing a porous plasma-enhanced chemical vapor deposited SiO x layer on top of p-GaN after which the sample is heated to 950°C in nitrogen ambient for 1 min followed by the removal of the SiO x layer in a buffered HF solution. A significant improvement of the conductivity of the p-GaN layer has been obtained.

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Electrical Characterization of Impurity-Free Disordered p-Type GaAs

Cited by 15 publications

References 30 publications

Impurity free vacancy disordering of InGaAs quantum dots

Impurity free vacancy disordering of InGaAs quantum dots

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

Enhancement of p-GaN Conductivity Using PECVD SiO[sub x]

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