D. Rosa-González - Academia.edu (original) (raw)
Papers by D. Rosa-González
The Particle Induced X-Ray Emission (PIXE) analytical technique with 16O ion beams (18 MeV) was a... more The Particle Induced X-Ray Emission (PIXE) analytical technique with 16O ion beams (18 MeV) was applied to the study of elemental composition at different brain regions of patients with a confirmed post-mortem diagnosis of Alzheimer’s disease and in samples from control subjects. The results obtained in the actual study show a clear correlation between occurrence of Alzheimer’s disease and the
Journal of Applied Physics, 2005
A study by transmission electron microscopy of the influence of the In and N contents in the rang... more A study by transmission electron microscopy of the influence of the In and N contents in the ranges of 20%-35% and 1.1%-3%, respectively, on the microstructure of Ga1-xInxNyAs1-y quantum wells is presented. Frank dislocation loops characterized as extrinsic have been found in the samples with x>=0.25. In these structures, threading dislocations appear as a consequence of the unfaulting of the loops for y>=0.014. An analysis of the density and size of the dislocation loops has provided an estimation of the critical radius for the unfaulting process. A model for this critical radius of the unfaulting process of extrinsic Frank loops is proposed. From this model and experimental values of critical radius, an estimation of the stacking fault energy of the GaInNAs alloy has been made. We have found a reduction in the stacking fault energy of the GaInNAs alloys when increasing the N content from 1.4% to 2.3% in good agreement with the theoretical estimation of the stacking fault energies of zinc-blende GaN and InN.
Journal of Applied Physics, 2005
ABSTRACT Composition modulation observed in GaInNAs quantum wells imposes an important handicap t... more ABSTRACT Composition modulation observed in GaInNAs quantum wells imposes an important handicap to their potential application within optical components, particularly as the indium and nitrogen contents are increased to reach longer wavelengths. In this paper, we compare our experimental results of phase separation in GaInNAs quantum wells grown at different temperatures with recent theoretical models of spinodal decomposition from the literature. This comparison has shown that the regular solution approximation, which explains the higher composition modulation compared to GaInAs samples, provides a more appropriate explanation of GaInNAs decomposition than the usual delta lattice-parameter approximation. Transmission electron microscopy shows no composition modulation contrasts with the chemical sensitive 002 dark field reflection and a strong increase in the intensity of the strain contrasts observed with 220 bright field reflection as the growth temperature increases from 360 to 460 °C. These observations can be explained by an uncoupling between N and In composition profiles forming separate In-rich and N-rich regions according to the regular solution approximation model. We therefore believe that the compositional fluctuations in GaInNAs are not only due to GaInAs decomposition, but that an uncoupled modulation of the III and V elements is also present.
Journal of Applied Physics, 2006
The strain-relaxation phenomena and the formation of a dislocation network in 2H-InN epilayers du... more The strain-relaxation phenomena and the formation of a dislocation network in 2H-InN epilayers during molecular beam epitaxy are reported. Plastic and elastic strain relaxations were studied by reflection high-energy electron diffraction, transmission electron microscopy, and high resolution x-ray diffraction. Characterization of the surface properties has been performed using atomic force microscopy and photoelectron spectroscopy. In the framework of the growth model the following stages of the strain relief have been proposed: plastic relaxation of strain by the introduction of geometric misfit dislocations, elastic strain relief during island growth, formation of threading dislocations induced by the coalescence of the islands, and relaxation of elastic strain by the introduction of secondary misfit dislocations. The model emphasizes the determining role of the coalescence process in the formation of a dislocation network in heteroepitaxially grown 2H-InN. Edge-type threading dislocations and dislocations of mixed character have been found to be dominating defects in the wurtzite InN layers. It has been shown that the threading dislocation density decreases exponentially during the film growth due to recombination and, hence, annihilation of dislocations, reaching ϳ10 9 cm −2 for ϳ2200 nm thick InN films.
Journal of Applied Physics, 2007
In this work, coalescence aspects of wurtzite-III-nitride epitaxy are addressed. The coalescence ... more In this work, coalescence aspects of wurtzite-III-nitride epitaxy are addressed. The coalescence phenomena have been studied in thin epilayers by means of electron and atomic force microscopies, and electron and x-ray diffractions. This study generalizes the growth parameters responsible for the rapid coalescence of III-nitride films, and describes the coalescence qualitatively and, partly, analytically for the case of heteroepitaxy in
Journal of Applied Physics, 2008
We report on the compositional dependencies of electron transport and photoconductive properties ... more We report on the compositional dependencies of electron transport and photoconductive properties for ultrathin metal-semiconductor-metal photodetectors based on In-rich InxGa1-xN alloys. For a In0.64Ga0.36N/GaN structure, the rise time close to the RC constant at low fields has been measured along with a transparency of ~77% and an absorbance of ~0.2 at a wavelength of 632 nm. The electron density profiles and low-field mobilities for different compositions of InGaN have been calculated by numerically solving the Schrödinger and Poisson equations and applying the ensemble Monte Carlo method, respectively. It was demonstrated that in ultrathin InxGa1-xN/GaN (0.5<x<1) heterostructures, in contrast to bulk InN exhibiting a strong surface electron accumulation, free electrons mostly tend to accumulate at the buried InGaN/GaN interface. We have also found that the low-field mobility in the InGaN/GaN heterostructures is strongly limited by the buried interface roughness which causes more than 95% of all scattering events occurred by two-dimensional electron transport under low electric field conditions.
Journal of Applied Physics, 2009
ABSTRACT The natural aging process of InN nanostructures by the formation of indium oxides is exa... more ABSTRACT The natural aging process of InN nanostructures by the formation of indium oxides is examined by transmission electron microscopy related techniques. Uncapped and GaN-capped InN quantum dots (QDs) on GaN/sapphire substrates were grown under the same conditions and kept at room temperature/pressure conditions. The GaN capping layer is found to preserve the InN QDs in the wurtzite phase, avoiding the formation of group-III oxides, while in the uncapped sample, a thin layer of cubic phases are formed that envelops the nucleus of wurtzite InN. These cubic phases are shown to be mainly bcc- In 2 O 3 for long aged samples where the nitrogen atoms in the InN surface layers have been substituted by atmospheric oxygen. This process implies the gradual transformation of the In sublattice from hcp to a quasi-fcc structure. Metastable zinc-blende InN phases rich in oxygen atoms are proposed to act as intermediate phases and they are evinced in samples less aged. The large concurrence of interplanar spaces, the twin formation, and the existence of a free surface that facilitates the transformation support this mechanism and would explain the high instability of the InN nanostructures at ambient conditions.
Applied Physics Letters, 2005
InN quantum dots (QDs) on GaN (0001) grown by metalorganic vapor phase epitaxy onto a sapphire su... more InN quantum dots (QDs) on GaN (0001) grown by metalorganic vapor phase epitaxy onto a sapphire substrate were studied by transmission electron microscopy (TEM). We found that the nucleation of InN QDs on GaN is directly related to the presence of threading dislocations (TDs) in the center of the QDs. The TEM analysis revealed that the TDs finish at the
Applied Physics Letters, 2011
Photoluminescence (PL) studies of GaN/Al x Ga 1-x N quantum dots (QDs) in nanowires demonstrate a... more Photoluminescence (PL) studies of GaN/Al x Ga 1-x N quantum dots (QDs) in nanowires demonstrate an efficient carrier confinement, resulting in thermally stable decay times up to 300 K. The evolution of the PL transition energy as a function of the QD height and of the Al mole fraction in the barriers, as well as the evolution of the decay time as a function of the QD height, point out that a built-in electric field is significantly smaller than the value expected from the spontaneous polarization discontinuity. This is explained by the uniaxial compressive strain resulted from the spontaneously-formed Al-rich shell that envelops the QD stack.
Applied Physics Letters, 1997
This paper describes the modeling of the dislocation distribution and of the strain relief in lin... more This paper describes the modeling of the dislocation distribution and of the strain relief in linearly and step-graded structures, based on work-hardening considerations. The model considers the energy variation in an InGaAs/GaAs system upon introducing a new dislocation into the interfacial fixed array of misfit dislocations. An analytical expression for the strain relaxation in graded-buffer structures is proposed. Transmission electron
Applied Physics Letters, 1997
A modelization of the strain relaxation in single heteroepitaxial layers is presented in this let... more A modelization of the strain relaxation in single heteroepitaxial layers is presented in this letter. The calculations consider the energetic variations of the heteroepitaxial structure when introducing one new dislocation into the existing interfacial array of fixed misfit dislocations without continuous readjustment of the spacing array. The interaction energy of the new dislocation with both lattice mismatch and dislocation array
![Research paper thumbnail of Strain relaxation behavior of In[sub x]Ga[sub 1−x]As quantum wells on vicinal GaAs (111)B substrates](https://attachments.academia-assets.com/41370632/thumbnails/1.jpg)
](Applied Physics Letters, 2002
Applied Physics Letters, 2001
Longwavelength InGaAs/GaAs quantum-well infrared photodetectors with indium contents ranging from... more Longwavelength InGaAs/GaAs quantum-well infrared photodetectors with indium contents ranging from 25% to 40% have been grown and characterized. Material quality has been assessed by photoluminescence and transmission electron microscopy. Intersubband photocurrent, excited by polarized (TE or TM) infrared light, has been analyzed in order to determine the responsivity for normal-incident radiation. It is found that the TE to TM responsivity ratio is lower than 10% in all the samples studied. By changing the indium content from 25% to 40%, the increase in the TE to TM photoresponse ratio is as low as 3%. Our results are opposite to previous reports of experimental observation of significant TE-polarized light absorption. However, the low efficiency for normal-incident radiation agrees with various theoretical predictions.
Applied Physics Letters, 2006
... Electronic mail: marina.gutierrez@uca.es. g002DF CS TEM micrograph of five layers QDs structu... more ... Electronic mail: marina.gutierrez@uca.es. g002DF CS TEM micrograph of five layers QDs structures, showing the enlargement of the dots during the stacking process. g400BF CS TEM image of the designed structure of QDs ...
Applied Physics Letters, 2007
... The effect of the introduction of a thick, low temperature GaN capping layer on ... Conventio... more ... The effect of the introduction of a thick, low temperature GaN capping layer on ... Conventional and high resolution transmission electron microscopy (HRTEM) in cross section (XTEM) and plan ... of these QDs occurs preferentially on top of pure edge threading dislocations from the ...
Applied Physics Letters, 2007
... PAAnderson, CEKendrick, TELee, W.Diehl, RJReeves, VJKennedy, A.Markwitz, RJKinsey, and SMDurb... more ... PAAnderson, CEKendrick, TELee, W.Diehl, RJReeves, VJKennedy, A.Markwitz, RJKinsey, and SMDurbin, Mater. ... V.Lebedev, V.Cimalla, J.Pezoldt, M.Himmerlich, S.Krischok, JASchaefer, O.Ambacher, FMMorales, JGLozano, and D.González, Effect of dislocations on electrical ...
Applied Physics Letters, 2012
X-ray luminescence of CdTe quantum dots in LaF3:Ce/CdTe nanocomposites Appl. Phys. Lett. 100, 013... more X-ray luminescence of CdTe quantum dots in LaF3:Ce/CdTe nanocomposites Appl. Phys. Lett. 100, 013109 Effects of composition and compositional distribution on the electronic structure of ZnSe1xTex ternary quantum dots J. Appl. Phys. 110, 123509 Gate-controlled electron g-factor in lateral quantum dot molecules J. Appl. Phys. 110, 124309 Tunable singlet-triplet splitting in a few-electron Si/SiGe quantum dot Appl. Phys. Lett. 99, 233108 Anisotropy of electron and hole g-factors in (In,Ga)As quantum dots Appl. Phys. Lett. 99, 221914 (2011) Additional information on Appl. Phys. Lett.
Applied Physics Letters, 2012
Polarization-resolved resonant fluorescence of a single semiconductor quantum dot Appl. Phys. Let... more Polarization-resolved resonant fluorescence of a single semiconductor quantum dot Appl. Phys. Lett. 101, 251118 (2012) Optical cavity efficacy and lasing of focused ion beam milled GaN/InGaN micropillars J. Appl. Phys. 112, 113516 (2012) Competitive carrier interactions influencing the emission dynamics of GaAsSb-capped InAs quantum dots Appl. Phys. Lett. 101, 231109 Fluorescence quantum efficiency of CdSe/ZnS quantum dots embedded in biofluids: pH dependence J. Appl. Phys. 112, 104704 (2012)
Applied Physics Letters, 2011
The effect of low N-alloying on the structure of capped InAs/GaAs quantum dots is analyzed by tra... more The effect of low N-alloying on the structure of capped InAs/GaAs quantum dots is analyzed by transmission electron microscopy related techniques. A statistical study of interplanar distances in InAsN quantum dots shows an increase in the lattice parameter compared to the InAs case. We suggest that the addition of nitrogen blocks the Ga/In exchange processes during the quantum dot capping
The Particle Induced X-Ray Emission (PIXE) analytical technique with 16O ion beams (18 MeV) was a... more The Particle Induced X-Ray Emission (PIXE) analytical technique with 16O ion beams (18 MeV) was applied to the study of elemental composition at different brain regions of patients with a confirmed post-mortem diagnosis of Alzheimer’s disease and in samples from control subjects. The results obtained in the actual study show a clear correlation between occurrence of Alzheimer’s disease and the
Journal of Applied Physics, 2005
A study by transmission electron microscopy of the influence of the In and N contents in the rang... more A study by transmission electron microscopy of the influence of the In and N contents in the ranges of 20%-35% and 1.1%-3%, respectively, on the microstructure of Ga1-xInxNyAs1-y quantum wells is presented. Frank dislocation loops characterized as extrinsic have been found in the samples with x>=0.25. In these structures, threading dislocations appear as a consequence of the unfaulting of the loops for y>=0.014. An analysis of the density and size of the dislocation loops has provided an estimation of the critical radius for the unfaulting process. A model for this critical radius of the unfaulting process of extrinsic Frank loops is proposed. From this model and experimental values of critical radius, an estimation of the stacking fault energy of the GaInNAs alloy has been made. We have found a reduction in the stacking fault energy of the GaInNAs alloys when increasing the N content from 1.4% to 2.3% in good agreement with the theoretical estimation of the stacking fault energies of zinc-blende GaN and InN.
Journal of Applied Physics, 2005
ABSTRACT Composition modulation observed in GaInNAs quantum wells imposes an important handicap t... more ABSTRACT Composition modulation observed in GaInNAs quantum wells imposes an important handicap to their potential application within optical components, particularly as the indium and nitrogen contents are increased to reach longer wavelengths. In this paper, we compare our experimental results of phase separation in GaInNAs quantum wells grown at different temperatures with recent theoretical models of spinodal decomposition from the literature. This comparison has shown that the regular solution approximation, which explains the higher composition modulation compared to GaInAs samples, provides a more appropriate explanation of GaInNAs decomposition than the usual delta lattice-parameter approximation. Transmission electron microscopy shows no composition modulation contrasts with the chemical sensitive 002 dark field reflection and a strong increase in the intensity of the strain contrasts observed with 220 bright field reflection as the growth temperature increases from 360 to 460 °C. These observations can be explained by an uncoupling between N and In composition profiles forming separate In-rich and N-rich regions according to the regular solution approximation model. We therefore believe that the compositional fluctuations in GaInNAs are not only due to GaInAs decomposition, but that an uncoupled modulation of the III and V elements is also present.
Journal of Applied Physics, 2006
The strain-relaxation phenomena and the formation of a dislocation network in 2H-InN epilayers du... more The strain-relaxation phenomena and the formation of a dislocation network in 2H-InN epilayers during molecular beam epitaxy are reported. Plastic and elastic strain relaxations were studied by reflection high-energy electron diffraction, transmission electron microscopy, and high resolution x-ray diffraction. Characterization of the surface properties has been performed using atomic force microscopy and photoelectron spectroscopy. In the framework of the growth model the following stages of the strain relief have been proposed: plastic relaxation of strain by the introduction of geometric misfit dislocations, elastic strain relief during island growth, formation of threading dislocations induced by the coalescence of the islands, and relaxation of elastic strain by the introduction of secondary misfit dislocations. The model emphasizes the determining role of the coalescence process in the formation of a dislocation network in heteroepitaxially grown 2H-InN. Edge-type threading dislocations and dislocations of mixed character have been found to be dominating defects in the wurtzite InN layers. It has been shown that the threading dislocation density decreases exponentially during the film growth due to recombination and, hence, annihilation of dislocations, reaching ϳ10 9 cm −2 for ϳ2200 nm thick InN films.
Journal of Applied Physics, 2007
In this work, coalescence aspects of wurtzite-III-nitride epitaxy are addressed. The coalescence ... more In this work, coalescence aspects of wurtzite-III-nitride epitaxy are addressed. The coalescence phenomena have been studied in thin epilayers by means of electron and atomic force microscopies, and electron and x-ray diffractions. This study generalizes the growth parameters responsible for the rapid coalescence of III-nitride films, and describes the coalescence qualitatively and, partly, analytically for the case of heteroepitaxy in
Journal of Applied Physics, 2008
We report on the compositional dependencies of electron transport and photoconductive properties ... more We report on the compositional dependencies of electron transport and photoconductive properties for ultrathin metal-semiconductor-metal photodetectors based on In-rich InxGa1-xN alloys. For a In0.64Ga0.36N/GaN structure, the rise time close to the RC constant at low fields has been measured along with a transparency of ~77% and an absorbance of ~0.2 at a wavelength of 632 nm. The electron density profiles and low-field mobilities for different compositions of InGaN have been calculated by numerically solving the Schrödinger and Poisson equations and applying the ensemble Monte Carlo method, respectively. It was demonstrated that in ultrathin InxGa1-xN/GaN (0.5<x<1) heterostructures, in contrast to bulk InN exhibiting a strong surface electron accumulation, free electrons mostly tend to accumulate at the buried InGaN/GaN interface. We have also found that the low-field mobility in the InGaN/GaN heterostructures is strongly limited by the buried interface roughness which causes more than 95% of all scattering events occurred by two-dimensional electron transport under low electric field conditions.
Journal of Applied Physics, 2009
ABSTRACT The natural aging process of InN nanostructures by the formation of indium oxides is exa... more ABSTRACT The natural aging process of InN nanostructures by the formation of indium oxides is examined by transmission electron microscopy related techniques. Uncapped and GaN-capped InN quantum dots (QDs) on GaN/sapphire substrates were grown under the same conditions and kept at room temperature/pressure conditions. The GaN capping layer is found to preserve the InN QDs in the wurtzite phase, avoiding the formation of group-III oxides, while in the uncapped sample, a thin layer of cubic phases are formed that envelops the nucleus of wurtzite InN. These cubic phases are shown to be mainly bcc- In 2 O 3 for long aged samples where the nitrogen atoms in the InN surface layers have been substituted by atmospheric oxygen. This process implies the gradual transformation of the In sublattice from hcp to a quasi-fcc structure. Metastable zinc-blende InN phases rich in oxygen atoms are proposed to act as intermediate phases and they are evinced in samples less aged. The large concurrence of interplanar spaces, the twin formation, and the existence of a free surface that facilitates the transformation support this mechanism and would explain the high instability of the InN nanostructures at ambient conditions.
Applied Physics Letters, 2005
InN quantum dots (QDs) on GaN (0001) grown by metalorganic vapor phase epitaxy onto a sapphire su... more InN quantum dots (QDs) on GaN (0001) grown by metalorganic vapor phase epitaxy onto a sapphire substrate were studied by transmission electron microscopy (TEM). We found that the nucleation of InN QDs on GaN is directly related to the presence of threading dislocations (TDs) in the center of the QDs. The TEM analysis revealed that the TDs finish at the
Applied Physics Letters, 2011
Photoluminescence (PL) studies of GaN/Al x Ga 1-x N quantum dots (QDs) in nanowires demonstrate a... more Photoluminescence (PL) studies of GaN/Al x Ga 1-x N quantum dots (QDs) in nanowires demonstrate an efficient carrier confinement, resulting in thermally stable decay times up to 300 K. The evolution of the PL transition energy as a function of the QD height and of the Al mole fraction in the barriers, as well as the evolution of the decay time as a function of the QD height, point out that a built-in electric field is significantly smaller than the value expected from the spontaneous polarization discontinuity. This is explained by the uniaxial compressive strain resulted from the spontaneously-formed Al-rich shell that envelops the QD stack.
Applied Physics Letters, 1997
This paper describes the modeling of the dislocation distribution and of the strain relief in lin... more This paper describes the modeling of the dislocation distribution and of the strain relief in linearly and step-graded structures, based on work-hardening considerations. The model considers the energy variation in an InGaAs/GaAs system upon introducing a new dislocation into the interfacial fixed array of misfit dislocations. An analytical expression for the strain relaxation in graded-buffer structures is proposed. Transmission electron
Applied Physics Letters, 1997
A modelization of the strain relaxation in single heteroepitaxial layers is presented in this let... more A modelization of the strain relaxation in single heteroepitaxial layers is presented in this letter. The calculations consider the energetic variations of the heteroepitaxial structure when introducing one new dislocation into the existing interfacial array of fixed misfit dislocations without continuous readjustment of the spacing array. The interaction energy of the new dislocation with both lattice mismatch and dislocation array
Applied Physics Letters, 2002
Applied Physics Letters, 2001
Longwavelength InGaAs/GaAs quantum-well infrared photodetectors with indium contents ranging from... more Longwavelength InGaAs/GaAs quantum-well infrared photodetectors with indium contents ranging from 25% to 40% have been grown and characterized. Material quality has been assessed by photoluminescence and transmission electron microscopy. Intersubband photocurrent, excited by polarized (TE or TM) infrared light, has been analyzed in order to determine the responsivity for normal-incident radiation. It is found that the TE to TM responsivity ratio is lower than 10% in all the samples studied. By changing the indium content from 25% to 40%, the increase in the TE to TM photoresponse ratio is as low as 3%. Our results are opposite to previous reports of experimental observation of significant TE-polarized light absorption. However, the low efficiency for normal-incident radiation agrees with various theoretical predictions.
Applied Physics Letters, 2006
... Electronic mail: marina.gutierrez@uca.es. g002DF CS TEM micrograph of five layers QDs structu... more ... Electronic mail: marina.gutierrez@uca.es. g002DF CS TEM micrograph of five layers QDs structures, showing the enlargement of the dots during the stacking process. g400BF CS TEM image of the designed structure of QDs ...
Applied Physics Letters, 2007
... The effect of the introduction of a thick, low temperature GaN capping layer on ... Conventio... more ... The effect of the introduction of a thick, low temperature GaN capping layer on ... Conventional and high resolution transmission electron microscopy (HRTEM) in cross section (XTEM) and plan ... of these QDs occurs preferentially on top of pure edge threading dislocations from the ...
Applied Physics Letters, 2007
... PAAnderson, CEKendrick, TELee, W.Diehl, RJReeves, VJKennedy, A.Markwitz, RJKinsey, and SMDurb... more ... PAAnderson, CEKendrick, TELee, W.Diehl, RJReeves, VJKennedy, A.Markwitz, RJKinsey, and SMDurbin, Mater. ... V.Lebedev, V.Cimalla, J.Pezoldt, M.Himmerlich, S.Krischok, JASchaefer, O.Ambacher, FMMorales, JGLozano, and D.González, Effect of dislocations on electrical ...
Applied Physics Letters, 2012
X-ray luminescence of CdTe quantum dots in LaF3:Ce/CdTe nanocomposites Appl. Phys. Lett. 100, 013... more X-ray luminescence of CdTe quantum dots in LaF3:Ce/CdTe nanocomposites Appl. Phys. Lett. 100, 013109 Effects of composition and compositional distribution on the electronic structure of ZnSe1xTex ternary quantum dots J. Appl. Phys. 110, 123509 Gate-controlled electron g-factor in lateral quantum dot molecules J. Appl. Phys. 110, 124309 Tunable singlet-triplet splitting in a few-electron Si/SiGe quantum dot Appl. Phys. Lett. 99, 233108 Anisotropy of electron and hole g-factors in (In,Ga)As quantum dots Appl. Phys. Lett. 99, 221914 (2011) Additional information on Appl. Phys. Lett.
Applied Physics Letters, 2012
Polarization-resolved resonant fluorescence of a single semiconductor quantum dot Appl. Phys. Let... more Polarization-resolved resonant fluorescence of a single semiconductor quantum dot Appl. Phys. Lett. 101, 251118 (2012) Optical cavity efficacy and lasing of focused ion beam milled GaN/InGaN micropillars J. Appl. Phys. 112, 113516 (2012) Competitive carrier interactions influencing the emission dynamics of GaAsSb-capped InAs quantum dots Appl. Phys. Lett. 101, 231109 Fluorescence quantum efficiency of CdSe/ZnS quantum dots embedded in biofluids: pH dependence J. Appl. Phys. 112, 104704 (2012)
Applied Physics Letters, 2011
The effect of low N-alloying on the structure of capped InAs/GaAs quantum dots is analyzed by tra... more The effect of low N-alloying on the structure of capped InAs/GaAs quantum dots is analyzed by transmission electron microscopy related techniques. A statistical study of interplanar distances in InAsN quantum dots shows an increase in the lattice parameter compared to the InAs case. We suggest that the addition of nitrogen blocks the Ga/In exchange processes during the quantum dot capping