GaAs/AlGaAs quantum wires fabricated by SiO2 capping-induced intermixing

Articles you may be interested inStructural characterization of metal organic vapor phase epitaxy grown GaInNAs quantum well with InGaAs and GaNAs barriers GaIn͑N͒As/ GaAs and GaIn͑N͒As/ GaNAs/ GaAs quantum well ͑QW͒ samples, with and without GaNAs strain-compensating layers ͑SCLs͒, were grown on GaAs ͑001͒ substrates by molecular beam epitaxy. Photoluminescence ͑PL͒ was used to study the effects of the GaNAs SCL on the properties of the Ga͑In͒NAs QWs upon annealing. We observed that the insertion of GaNAs SCL produced a distinct increase in the PL blueshift as a function of annealing time. X-ray diffraction from the strain-compensated GaIn͑N͒As QWs before and after annealing showed no N atom diffusion, but exhibited Ga-In atom interdiffusion across the QW interfaces. We compared the effects of the GaNAs SCL on the PL blueshift with those of the SiO 2 encapsulant upon annealing. The increased PL blueshift caused by the GaNAs SCL for t ann ഛ 40 s is attributed to the further Ga m In 4−m -N ͑0 ഛ m ഛ 4͒ changes due to greater local strain caused by GaNAs ͑SCL͒ quantum barriers as compared with GaAs barriers. For t ann Ͼ 40 s, the nonsaturable blueshift caused by GaNAs SCL is attributed to defect-assisted ͑especially, Ga vacancies͒ Ga/ In interdiffusion, since the density of Ga vacancy defects in the GaNAs SCLs is quite high.

Section: Resultsmentioning

confidence: 99%

Influence of GaNAs strain-compensation layers on the optical properties of GaIn(N)As∕GaAs quantum wells upon annealing

Liu

Xiang

2006

“…Work has been carried out to try to suppress the thermal interdiffusion. 13,16 In Fig. SiO 2 has a much smaller thermal expansion coefficient 14 ͑0.52ϫ 10 −6°C−1 ͒ than GaAs ͑6.03 ϫ 10 −6°C−1 ͒; 15 this creates a stress on the SiO 2 / GaAs interface region during annealing.…”

Section: Controlled Interdiffusionmentioning

confidence: 99%

Impurity free vacancy disordering of InGaAs quantum dots

Lever¹,

Tan²,

Jagadish³

2004

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.

“…Similar results have previously been obtained for the ground state for n = 1.63. 62 Hazell et al 34 have shown that the Ga outdiffusion into the SiO x N y cap layer decreases with increasing nitrogen content ͑increasing stress͒ and this results in a decreasing blueshift. However, blueshift for the films of different compositions is not simply related to the amount of Ga ͑and In͒ outdiffused into the dielectric.…”

Section: Influence Of Cap Layer Composition On the Qw Optical Tranmentioning

confidence: 99%

Photoreflectance investigations of quantum well intermixing processes in compressively strained InGaAsP∕InGaAsP quantum well laser structures emitting at 1.55μm

Podhorodecki

Andrzejewski

Kudrawiec

et al. 2006

Large blueshift in InGaAs/InGaAsP laser structure using inductively coupled argon plasma-enhanced quantum well intermixing Influence of dielectric deposition parameters on the In 0.2 Ga 0.8 As / GaAs quantum well intermixing by impurity-free vacancy disordering Enhanced band-gap blueshift due to group V intermixing in InGaAsP multiple quantum well laser structures induced by low temperature grown InPWe have investigated the effects of interdiffusion and its technological parameters on the subband structure in compressively strained InGaAsP quantum wells ͑QWs͒ using photoreflectance and photoluminescence techniques. p-i-n laser structures with three QWs were grown by gas source molecular beam epitaxy and capped with dielectric films deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition and annealed using a rapid thermal annealing process. A numerical real-time wave-packet propagation method including static electric field, strain in the wells and barriers, and error function interface diffusion modeling is used to calculate the transition energies for the diffused QWs. It has been shown that the shift of the energy levels due to the interdiffusion related changes of the well confinement potential profile is a consequence of two competing processes: a change of the well width and an effective increase of the band gap energy resulting in a net blueshift of all optical transitions. Moreover, it has been found that quantum well intermixing does not significantly influence the built-in electric fields distribution.