Dependence of the photoluminescence of annealed III-V semiconductor quantum dots on their shape and dimension
TL;DR: In this article, the effects of interdiffusion in realistic InXGa1−XAs/GaAs and inXGa 1−XN/GaN QDs with various geometries such as pyramids, truncated pyramids and lens shaped, through quantum mechanical computations are investigated.
Abstract: Interdiffusion in III-V semiconductor quantum dots (QDs) may occur during growth and subsequent device processing steps. The photoluminescence (PL) spectra of InXGa1−XAs/GaAs and InXGa1−XN/GaN QDs change significantly on annealing. The size and shape of a QD dot are important parameters, which govern this change of the PL spectra. In this communication, we have investigated the effects of interdiffusion in realistic InXGa1−XAs/GaAs and InXGa1−XN/GaN QDs with various geometries which are of theoretical and practical interest such as pyramidal, truncated pyramidal, and lens shaped, through quantum mechanical computations.
Citations
More filters
TL;DR: In this article, the photoluminescence (PL) spectra of annealed InGaN/GaN ultrathin In-rich (UTIR) quantum wells (QWs) and ultrasmall Inrich (USIR) QDs were analyzed by taking into account the changes in the energy band profiles due to annealing and interdiffusion.
TL;DR: In this paper, uniform InGaN nanodots were successfully grown on SiO2 pretreated GaN surface and dual-color emissions with different behavior were observed from photoluminescence (PL) spectrum.
Abstract: Uniform InGaN nanodots were successfully grown on SiO2 pretreated GaN surface. It was found that the InGaN nanodots were 20 nm in diameter and 5 nm in height, approximately. After the growth of two peri- ods of InGaN/GaN quantum wells on the surface of In- GaN nanodots, nanodot structure still formed in the In- GaN well layer caused by the enhanced phase separation phenomenon. Dual-color emissions with different behavior were observed from photoluminescence (PL) spectrum of InGaN nanodots hybrid with InGaN/GaN quantum wells. A significant blueshift and a linewidth broadening were mea- sured for the low-energy peak as the increase of PL excita- tion power, while a slight blueshift and a linewidth narrow- ing occurred for the high-energy peak. Accordingly, these two peaks were assigned to be from the In-rich nanodots and quantized state transition from the InGaN/GaN quan- tum wells with indium content, respectively.
References
More filters
Book•
01 Jan 1999
TL;DR: In this paper, the growth and structural characterisation of self-organized Quantum Dots are discussed. But they do not consider the model of ideal and real quantum Dots.
Abstract: Fabrication Techniques for Quantum Dots. Self-Organization Concepts on Crystal Surfaces. Growth and Structural Characterization of Self-Organized Quantum Dots. Modeling of Ideal and Real Quantum Dots. Electronic and Optical Properties. Electrical Properties. Photonic Devices. References. Index.
2,356 citations
TL;DR: In this paper, large energy shifts in the luminescence emission from strained InGaAs quantum dots are observed as a result of postgrowth annealing and also when raising the upper cladding layer growth temperatures.
Abstract: Large energy shifts in the luminescence emission from strained InGaAs quantum dots are observed as a result of postgrowth annealing and also when raising the upper cladding layer growth temperatures. These blueshifts occur concurrently with narrowing (from 61 to 24 meV) of the full width at half‐maxima for the emission from the quantum dot ensemble. These energy shifts can be explained by interdiffusion or intermixing of the interfaces rather than strain effects due to variations in capping layer thickness. Temperature behavior of the luminescence in annealed and nonannealed samples indicates a change in the shape and depth of the quantum dot confining potential. Quenching of the wetting layer luminescence after interdiffusion is also observed.
252 citations
TL;DR: In this article, the relationship between exciton states and structural parameters of QDs is studied in detail, including three-dimensional confinement of the electrons and holes in QDs and a strong built-in electric field effect due to the piezoelectricity and spontaneous polarization.
Abstract: Exciton states confined in wurtzite InxGa1−xN/GaN strained quantum dots (QDs) are investigated within the framework of effective-mass approximation and variational approach, including three-dimensional confinement of the electrons and holes in QDs and a strong built-in electric field effect due to the piezoelectricity and spontaneous polarization. The relationship between exciton states and structural parameters of QDs is studied in detail. Our results show that the In-rich QDs-like are formed spontaneously due to In compositional fluctuations in the InxGa1−xN layer. The strong built-in electric field in InxGa1−xN/GaN strained QDs gives rise to a marked reduction of the effective band gap of QDs and leads to a remarkable electron–hole spatial separation. This effect has a strong influence on exciton states and optical properties of QDs especially for the QDs with large height (⩾5 nm) along the grown direction of the heterostructures. A good agreement has been obtained between the calculated and measured emission wavelengths for different InxGa1−xN/GaN strained QDs.
158 citations
TL;DR: It is found that the second InGaAs QD layer sensitively responds to the lateral strain-field interferences generated by the buried periodic QD array, including the well-known formation of vertically aligned QDs but also the occurrence of QDs on satellite strain energy density minima.
Abstract: Twofold stacked $\mathrm{I}\mathrm{n}\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ quantum dot (QD) layers are grown on GaAs(001) substrates patterned with square arrays of shallow holes We study the surface morphology of the second InGaAs QD layer as a function of pattern periodicity Comparing our experimental results with a realistic simulation of the strain energy density ${E}_{\mathrm{s}\mathrm{t}\mathrm{r}}$ distribution, we find that the second InGaAs QD layer sensitively responds to the lateral strain-field interferences generated by the buried periodic QD array This response includes the well-known formation of vertically aligned QDs but also the occurrence of QDs on satellite strain energy density minima Our calculations show that base size and shape as well as lateral orientation of both QD types are predefined by the ${E}_{\mathrm{s}\mathrm{t}\mathrm{r}}$ distribution on the underlying surface
82 citations
TL;DR: In this article, postgrowth thermal annealing of an InGaN/GaN quantum-well sample with a medium level of nominal indium content (19%) was conducted.
Abstract: Postgrowth thermal annealing of an InGaN/GaN quantum-well sample with a medium level of nominal indium content (19%) was conducted. From the analyses of high-resolution transmission electron microscopy and energy filter transmission electron microscopy, it was found that thermal annealing at 900 °C led to a quasiregular quantum-dot-like structure. However, such a structure was destroyed when the annealing temperature was raised to 950 °C. Temperature-dependent photoluminescence (PL) measurements showed quite consistent results. Blueshift of the PL peak position and narrowing of the PL spectral width after thermal annealing were observed.
81 citations