Strain relaxation in InAs∕InGaAs quantum dots investigated by photoluminescence and capacitance-voltage profiling

Chen, J. F.; Hsiao, R. S.; Chen, Y. P.; Wang, J. S.; Y., J.

doi:10.1063/1.2081132

Cited by 20 publications

(13 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The FWHM increase is related to the presence of two peaks with lower (0.941 eV) and higher (0.957 eV) energies than for the sample with 5 nm thick cap layer (0.947 eV). An emission energy blue-shift resulting from strain relaxation has been already reported when the InAs coverage is increased beyond a critical thickness [11]. So, relaxed QDs are probably responsible of the stronger peak at 0.957 eV but the presence of the low energy peak also shows that the relaxation is not uniform.…”

Section: Introductionmentioning

confidence: 90%

Optimization of InAs/(Ga,In)As quantum dots in view of efficient emission at 1.5 µm

Hugues¹,

Richter

Damilano

et al. 2006

Phys. Status Solidi (c)

View full text Add to dashboard Cite

InAs self-organized quantum dots covered by low temperature (Ga,In)As layer with different thicknesses and indium contents have been grown on GaAs substrates by molecular beam epitaxy. The most efficient emission is obtained for islands covered by 5 nm thick Ga 0.85 In 0.15 As cap layer. A strong room temperature emission at 1.33 µm with a linewidth as narrow as 21 meV is observed. Moreover, the analysis of temperature dependent photoluminescence intensity indicates that the main quenching mechanism comes from carrier escape from the dots to the confined level of the quantum well formed by the cap layer and the wetting layer. 1 Introduction In the last few years, a lot of efforts has been devoted to develop laser structures emitting at 1.3 and 1.55 µm on GaAs substrate in order to replace the current InP technology for optical communication applications. Actually, laser emissions at 1.3 µm with competitive performances have been obtained with two different active layer configurations. The first approach is to use quaternary (Ga,In)(N,As) (GINA) quantum wells (QWs) while the second consists to cover InAs quantum dots (QDs) with (Ga,In)As layer. Nevertheless, efficient emission at longer wavelengths is difficult to achieve whatever the approach used. The most common way is to use GINA QWs but the high nitrogen content required (around 4%) decreases the radiative efficiency and results in lasers with high threshold current densities. Recently, lasers with improved performances at 1.55 µm have been obtained by adding antimony to form quinary QW [1]. On the other hand, by increasing the amount of deposited InAs or the In content in the cap layer, photoluminescence (PL) in the 1.5 µm range has been also reported for InAs QD strutures [2,3]. However, plastic relaxation resulting from the huge accumulated strain strongly degrades the PL efficiency and does not allow to stack several QDs layers necessary to obtain a sufficient gain for laser emission. Another approach is to use GINA QDs instead of InAs QDs, but the island size distribution becomes strongly inhomogeneous and the PL efficiency is degraded by the nitrogen related defects [4]. One promising way is to use a mixed approach : InAs QDs covered with GINA material [5,6]. Indeed, this approach enables to obtain homogeneous island size distribution and to decrease the accumulated strain in the cap layer. Using this approach, Ustinov et al have obtained PL emission at 1.54 µm with an intensity comparable to that of GINA QWs emitting at 1.3 µm [5]. The main problem with this structure is the relative incompatibility between the QDs and the cap layer optimum growth temperatures. Indeed, the best compromise between homogeneity and density of InAs QDs is obtained for

show abstract

Section: Introductionmentioning

confidence: 90%

Optimization of InAs/(Ga,In)As quantum dots in view of efficient emission at 1.5 µm

Hugues¹,

Richter

Damilano

et al. 2006

Phys. Status Solidi (c)

View full text Add to dashboard Cite

show abstract

“…1-16͒ is necessary for designing QD devices. 19 This blueshift contradicts an effect of compressive strain reduction in the QDs, which is expected to produce a redshift. Growing an InGaAs capping layer on top of the QDs leads to strain relaxation by the generation of the lattice misfits in the bottom GaAs layer near the QDs while the top GaAs layer is dislocation-free.…”

mentioning

confidence: 95%

Bimodel onset strain relaxation in InAs quantum dots with an InGaAs capping layer

Chen

Chiang

et al. 2010

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

Capping InAs quantum dots ͑QDs͒ with an InGaAs layer allows strain relaxation to induce a low-energy electron state below a set of fine dot family states, which is consistent with photoluminescence ͑PL͒ spectra. The evolution of InAs thickness suggests a bimodal onset relaxation, i.e., a fine dot family that is strain-relieved by indium outdiffusion from the QDs, as suggested by transmission electron microscopy, and a low-energy dot family that is strain relaxed by the generation of lattice misfits. The indium outdiffusion can explain an abnormal PL blueshift in 70 meV in the fine dot family at onset of strain relaxation.

show abstract

“…As a rule, the best optical quality of QDs is attained at a small excess of d eff over d *: d eff ~ (1.1-1.2) d *, although the quantity d * as such may vary within a rather wide range from 1.7 to 4 monolayers, depending on the substrate temperature, the relationship between the fluxes of reagents, and the particular type of the heteropair. The process of growth of QDs in InAs/GaAs heterostructures with the increased thickness d eff was studied elsewhere [1][2][3][4][5]. It was shown that, with increasing d eff , the dispersion of QDs in size and the number of relaxed large-sized defect InAs clusters increase along with the density of QDs.…”

Section: Introductionmentioning

confidence: 99%

10.1007/s11453-008-3010-9

2010

CrossRef Listing of Deleted DOIs

View full text Add to dashboard Cite

Multilayered InAs/GaAs quantum dot (QD) heterostructures are produced by metal-organic gas phase epitaxy. The structures exhibit photoluminescence around 1.55 µ m at 300 K. The specific feature of the technology is the growth of an InAs layer with an increased effective thickness d eff to form QDs, in combination with low-temperature overgrowth of the QDs with a thin (6-nm) GaAs layer and with the annealing of defects. By X-ray diffraction analysis and PL studies, it is shown that, in a structure with the increased thickness d eff , a secondary wetting InGaAs layer is produced on top of the QD layer from the growing relaxed large-sized InAs clusters on annealing. A new mechanism of formation of large-sized QDs characterized by a large "aspect ratio" is suggested. The mechanism involves the 2D-3D transformation of the secondary InGaAs layer in the field of elastic strains in previously formed QDs. The specific feature of the array of QDs is the coexistence of three populations of different-sized QDs responsible for the multimode photoluminescence in the range from 1 to 1.6 µ m. The potentialities of such structures for infrared photoelectric detectors operating in the range from 1 − 2.5 µ m at room temperature are analyzed.

show abstract

Strain relaxation in InAs∕InGaAs quantum dots investigated by photoluminescence and capacitance-voltage profiling

Cited by 20 publications

References 19 publications

Optimization of InAs/(Ga,In)As quantum dots in view of efficient emission at 1.5 µm

Optimization of InAs/(Ga,In)As quantum dots in view of efficient emission at 1.5 µm

Bimodel onset strain relaxation in InAs quantum dots with an InGaAs capping layer

10.1007/s11453-008-3010-9

Contact Info

Product

Resources

About