The challenges in guided self-assembly of Ge and InAs quantum dots on Si

Zhao, Yanyan; Yoon, Tae‐Sik; Wu, Feng; Li, B.Y.; Kim, Jae H; Liu, J.; Hulko, O.; Xie, Y. H.; Kim, H.M.; Kim, K.B.; Kim, H.J.; Wang, K.L.; Rätsch, Christian; Caflisch, Russel E.; Ryu, D.Y.; Russell, T. P.

doi:10.1016/j.tsf.2005.08.407

Cited by 19 publications

(12 citation statements)

References 19 publications

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“…Further understanding should help in the design and simulation of both spontaneous ''bottom up'' self-assembly and directed or guided self-assembly to enhance SAQD order. [18][19][20][21][22][23][24][25] Order prediction inherently involves the modeling of stochastic processes. Recently, SAQD order has been modeled using a deterministic model with stochastic initial conditions in the linear approximation.…”

Section: Introductionmentioning

confidence: 99%

Predicting and Understanding Order of Heteroepitaxial Quantum Dots

Friedman

2007

Journal of Elec Materi

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Heteroepitaxial self-assembled quantum dots (SAQDs) will allow breakthroughs in electronics and optoelectronics. SAQDs are a result of Stranski-Krastanow growth, whereby a growing planar film becomes unstable after an initial wetting layer is formed. Common systems are Ge x Si 1Àx =Si and In x Ga 1Àx As/GaAs: For applications, SAQD arrays need to be ordered. The roles of crystal anisotropy, random initial conditions and thermal fluctuations in influencing SAQD order during early stages of SAQD formation are studied through a simple stochastic model of surface diffusion. Surface diffusion is analyzed through a linear and perturbatively non-linear analysis. The role of crystal anisotropy in enhancing SAQD order is elucidated. It is also found that SAQD order is enhanced when the deposited film is allowed to evolve at heights near the critical wetting surface height that marks the onset of non-planar film growth.

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Section: Introductionmentioning

confidence: 99%

Predicting and Understanding Order of Heteroepitaxial Quantum Dots

Friedman

2007

Journal of Elec Materi

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“…By these methods, nanostructures mostly grow in random manner, and parameters of such materials are not controlled, it is the so-called self-assembly manner [9]. …”

Section: Introductionmentioning

confidence: 99%

Properties of nanocones formed on a surface of semiconductors by laser radiation: quantum confinement effect of electrons, phonons, and excitons

2011

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On the basis of the analysis of experimental results, a two-stage mechanism of nanocones formation on the irradiated surface of semiconductors by Nd:YAG laser is proposed for elementary semiconductors and solid solutions, such as Si, Ge, SiGe, and CdZnTe. Properties observed are explained in the frame of quantum confinement effect. The first stage of the mechanism is characterized by the formation of a thin strained top layer, due to redistribution of point defects in temperature-gradient field induced by laser radiation. The second stage is characterized by mechanical plastic deformation of the stained top layer leading to arising of nanocones, due to selective laser absorption of the top layer. The nanocones formed on the irradiated surface of semiconductors by Nd:YAG laser possessing the properties of 1D graded bandgap have been found for Si, Ge, and SiGe as well, however QD structure in CdTe was observed. The model is confirmed by "blue shift" of bands in photoluminescence spectrum, "red shift" of longitudinal optical line in Raman back scattering spectrum of Ge crystal, appearance of Ge phase in SiGe solid solution after irradiation by the laser at intensity 20 MW/cm2, and non-monotonous dependence of Si crystal micro-hardness as function of the laser intensity.

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“…6) Other methods for fabricating the ordered arrays of Ge nanodots include carbon predeposition using monomethylsilane, 7) selective oxidation of silicongermanium-on-insulator structure 8) and self-assembly processes. 9) When the size of the Ge nanodot becomes comparable to the Bohr exciton radius, quantum effects become relevant and the nanodot begins to exhibit quantum confinement effects. Consequently, the nanodot's electronic structure is characterized by a series of discrete quantum levels (similar to the discrete electronic structure observed in atoms), and differs significantly from that of the corresponding bulk solid.…”

Section: Introductionmentioning

confidence: 99%

Study of the Electronic Structure of Individual Free-Standing Germanium Nanodots Using Spectroscopic Scanning Capacitance Microscopy

Wong

2009

Jpn. J. Appl. Phys.

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High spatial resolution spectroscopic scanning capacitance microscopy (SCM) measurements at room temperature based on the differential capacitance (d C=d V ) versus probe tip-to-substrate bias characteristics, is directly used to characterize the electronic structure of a pyramidal and an ellipsoidal shaped germanium (Ge) nanodot (with physical sizes smaller than the Bohr exciton radius of Ge), among the arrays of Ge nanodots fabricated on a highly doped silicon substrate using an anodic alumina membrane as an evaporation mask. The ability to study the individual nanodots under the probe tip circumvents and isolates the statistical disorders encountered when studying large ensembles of size-dispersed nanodots. It is demonstrated that the spectra of the positive d C=dV peaks are reflective of the energetics of electron trapping in the quantized energy states inside the Ge nanodots. Furthermore, the spectroscopic SCM d C=dV profile is observed to be substantially influenced by the nanodot shape where the pyramidal Ge nanodot shows three distinct shells which are interpreted as the s-like ground state, the first excited p-like state and the second excited d-like state. On the other hand, the elliptical deformation of the ellipsoidal Ge nanodot breaks the shell structure which significantly affects its electronic structure. Using the spacing between the d C=d V peaks from the spectroscopic SCM measurements, an analytical expression is derived to calculate the energy separation between the different energy states in the Ge nanodots. #

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The challenges in guided self-assembly of Ge and InAs quantum dots on Si

Cited by 19 publications

References 19 publications

Predicting and Understanding Order of Heteroepitaxial Quantum Dots

Predicting and Understanding Order of Heteroepitaxial Quantum Dots

Properties of nanocones formed on a surface of semiconductors by laser radiation: quantum confinement effect of electrons, phonons, and excitons

Study of the Electronic Structure of Individual Free-Standing Germanium Nanodots Using Spectroscopic Scanning Capacitance Microscopy

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