Optical Absorption Probability for the Zone-Folding Induced Quasi-Direct Gap in Ge(x)Si(1−x)/Si Strained Layer Superlattices

AbstractUsing a realistic zone-folding scheme for a Ge(x)Si(1−x)/Si strained layer superlattice having a Si-like conduction band structure (i.e ≲85% Ge) we calculate the transition probability for the zone-folding induced direct optical gap and compare it with the indirect band gap absorption probability. The results suggest that such zone-folding induced direct optical transitions are promising for optical devices made from Ge(x)Si(1−x)/Si strained layer superlattices and like structures, provided they are fabricated in such a way that the appropriate zone-folding occurs.

Download Full-text

On the Existence of Multiple Equilibrium States in Strained-Layer Superlattices

MRS Proceedings ◽

10.1557/proc-103-61 ◽

1987 ◽

Vol 103 ◽

Cited By ~ 2

Author(s):

William C. Johnson

Keyword(s):

Free Energy ◽

Equilibrium State ◽

Stable Equilibrium ◽

Multiple Equilibrium ◽

Equilibrium Thermodynamic ◽

Relative Thickness ◽

Two Phase ◽

Strained Layer ◽

Strained Layer Superlattice ◽

Strained Layer Superlattices

ABSTRACTUsing recent results from the thermodynamics of stressed solids, two-phase coexistence in a simple binary strained-layer superlattice is examined. We show that for a given temperature and overall composition of the superlattice, there can exist more than one linearly stable, equilibrium thermodynamic state. That is, there may exist several combinations of relative thickness of the phases and corresponding phase compositions that minimize the free energy of the system. The equilibrium state observed experimentally can, therefore, be influenced by the processing path.

Download Full-text

Defect Reduction in GaAs Epilayers on Si Substrates Using Strained Layer Superlattices

MRS Proceedings ◽

10.1557/proc-91-99 ◽

1987 ◽

Vol 91 ◽

Cited By ~ 9

Author(s):

N. El-Masry ◽

N. Hamaguchi ◽

J.C.L. Tarn ◽

N. Karam ◽

T.P. Humphreys ◽

...

Keyword(s):

Thermal Annealing ◽

Rapid Thermal Annealing ◽

Buffer Layers ◽

Threading Dislocations ◽

Defect Reduction ◽

Strained Layer ◽

Si Substrates ◽

Density Of Dislocations ◽

Strained Layer Superlattice ◽

Strained Layer Superlattices

ABSTRACTInxGa11-xAs-GaAsl-yPy strained layer superlattice buffer layers have been used to reduce threading dislocations in GaAs grown on Si substrates. However, for an initially high density of dislocations, the strained layer superlattice is not an effective filtering system. Consequently, the emergence of dislocations from the SLS propagate upwards into the GaAs epilayer. However, by employing thermal annealing or rapid thermal annealing, the number of dislocation impinging on the SLS can be significantly reduced. Indeed, this treatment greatly enhances the efficiency and usefulness of the SLS in reducing the number of threading dislocations.

Download Full-text

The Growth of InAsSb/InGaAs Strained-Layer Superlattices by Metal-Organic Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-325-493 ◽

1993 ◽

Vol 325 ◽

Cited By ~ 3

Author(s):

R. M. Biefeld ◽

K. C. Baucom ◽

S. R. Kurtz ◽

D. M. Follstaedt

Keyword(s):

Chemical Vapor Deposition ◽

Thermodynamic Model ◽

Vapor Deposition ◽

Chemical Vapor ◽

Organic Chemical ◽

Strained Layer ◽

Strained Layer Superlattice ◽

Metal Organic ◽

Strained Layer Superlattices ◽

Organic Chemical Vapor Deposition

AbstractWe have grown InAsl-xSbx/Inl-yGayAs strained-layer superlattice (SLS) semiconductors lattice matched to InAs using a variety of conditions by metal-organic chemical vapor deposition. The V/III ratio was varied from 2.5 to 10 at a temperature of 475 °C, at pressures of 200 to 660 torr and growth rates of 3 - 5 A/s and layer thicknesses ranging from 55 to 152 Å. The composition of the InAsSb ternary can be predicted from the input gas molar flow rates using a thermodynamic model. At lower temperatures, the thermodynamic model must be modified to take account of the incomplete decomposition of arsine and trimethylantimony. Diodes have been prepared using Zn as the p-type dopant and undoped SLS as the n-type material. The diode was found to emit at 3.56 μm. These layers have been characterized by optical microscopy, SIMS, x-ray diffraction, and transmission electron diffraction. The optical properties of these SLS's were determined by infrared photoluminescence and absorption measurements.

Download Full-text

Raman Study of Strain and Confinement Effects in Si/Ge Strained Layer Superlattices Under Hydrostatic Pressure

MRS Proceedings ◽

10.1557/proc-220-333 ◽

1991 ◽

Vol 220 ◽

Author(s):

Zhifeng Sui ◽

Irving P. Herman ◽

Joze Bevk

Keyword(s):

Hydrostatic Pressure ◽

Raman Scattering ◽

Optical Phonon ◽

Phonon Frequency ◽

Optical Phonons ◽

Biaxial Strain ◽

Strained Layer ◽

Strained Layer Superlattice ◽

Raman Study ◽

Strained Layer Superlattices

ABSTRACTThe effects of strain and confinement on optical phonons in a Si12Ge4 strained layer superlattice grown by MBE on c-Si (001) were studied as a function of hydrostatic pressure (T = 295 K) using Raman scattering. The change of phonon frequency with pressure, dω/dP, for the principal quasi-confined LO mode in the Ge layers is found to be significantly smaller than that for bulk crystalline Ge because the magnitude of biaxial strain decreases in the Ge layers with added pressure and because the Grüneisen parameter of the confined mode is smaller than that of the Γ-point optical phonon. More generally, it is noted that the magnitude of biaxial strain in many strained layer superlattices initially decreases with the application of hydrostatic pressure, making the structures more stable.

Download Full-text

Defect studies in strained-layer quantum well heterostructures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074471 ◽

1983 ◽

Vol 41 ◽

pp. 120-121

Author(s):

J.M. Brown ◽

M.E. Mochel ◽

N. Holonyak ◽

M.D. Camras ◽

M.J. Ludowise ◽

...

Keyword(s):

Electron Microscope ◽

Epitaxial Growth ◽

Vapor Phase ◽

Microscope Study ◽

Electron Microscope Study ◽

Stimulated Emission ◽

High Excitation ◽

Strained Layer ◽

Strained Layer Superlattice ◽

Strained Layer Superlattices

The epitaxial growth of mismatched or strained III-V layers was shown to be viable as early as 1960. Osbourn et al suggested that strained layer GaP-GaAs1-xPx superlattices grown by organo-metal1ic vapor phase epitaxy (OMVPE) could be used to fold the Brillouin zone and make indirect-crystal direct. More recently, it has been shown that a strained-layer superlattice can be grown free enough of defects at heterointerfaces to make possible stimulated emission. This has been demonstrated on OMVPE GaAs1-xPx-GaAs (x=0.25) and GaAs-InxGa1-xAs (x=0.2) strained layer superlattices which have been operatedas photopuraped continuous (cw) 300K lasers but which at high excitation levels (> 103Acm-2) prove to be unstable. This paper presents the results of an electron microscope study of the defects produced in a GaAs-InxGa1-xAs strained superlattice as a result of high excitation levels of operation.

Download Full-text

Indirect, quasidirect, and direct optical transitions in the pseudomorphic (44)-monolayer Si-Ge strained-layer superlattice on Si(001)

Physical Review B ◽

10.1103/physrevb.36.1310 ◽

1987 ◽

Vol 36 (2) ◽

pp. 1310-1313 ◽

Cited By ~ 81

Author(s):

R. People ◽

S. A. Jackson

Keyword(s):

Optical Transitions ◽

Strained Layer ◽

Strained Layer Superlattice

Download Full-text

Theory of optical transitions in Si/Ge(001) strained-layer superlattices

Physical Review B ◽

10.1103/physrevb.36.9683 ◽

1987 ◽

Vol 36 (18) ◽

pp. 9683-9693 ◽

Cited By ~ 186

Author(s):

Mark S. Hybertsen ◽

Michael Schlüter

Keyword(s):

Optical Transitions ◽

Strained Layer ◽

Strained Layer Superlattices

Download Full-text

Growth of (GaAs)1−x (Si2)x Metastable Alloys using Migration-Enhanced Epitaxy

MRS Proceedings ◽

10.1557/proc-222-151 ◽

1991 ◽

Vol 222 ◽

Cited By ~ 1

Author(s):

T. Sudersena Rao ◽

Y. Horikoshi

Keyword(s):

Buffer Layers ◽

Double Crystal ◽

Cross Sectional ◽

Strained Layer ◽

Si Substrates ◽

Migration Enhanced Epitaxy ◽

Strained Layer Superlattice ◽

Metastable Alloys ◽

Si Content ◽

Strained Layer Superlattices

ABSTRACTEpitaxial (GaAs)1−x (Si2)x metastable alloys have been grown on GaAs (100) substrates using Migration-Enhanced Epitaxy in the composition range of 0<x<0.25. The lattice constant a0 of the alloys was found to decrease with increasing Si content from 0.56543nm at x=0 to 0.5601nm at x=0.25. Double-crystal x-ray diffraction rocking curve measurements and cross-sectional transmission electron microscopy studies made on a 10 period (GaAs)1−x(Si2)x/GaAs strained layer superlattice indicated sharp and abrupt interfaces. High crystalline quality GaAs has been grown on Si substrates using (GaAs)0.80(Si2)0.20/GaAs strained layer superlattices as buffer layers.

Download Full-text

Effect Of AlGaN/GaN Strained Layer Superlattice Period On InGaN MQW Laser Diodes

MRS Internet Journal of Nitride Semiconductor Research ◽

10.1557/s1092578300004026 ◽

2000 ◽

Vol 5 (S1) ◽

pp. 14-19 ◽

Cited By ~ 1

Author(s):

Monica Hansen ◽

Amber C. Abare ◽

Peter Kozodoy ◽

Thomas M. Katona ◽

Michael D. Craven ◽

...

Keyword(s):

Hole Concentration ◽

Laser Diodes ◽

Chemical Vapor ◽

Threshold Current ◽

Threshold Current Density ◽

Strained Layer ◽

Strained Layer Superlattice ◽

Strained Layer Superlattices ◽

Cladding Layers ◽

Superlattice Period

AlGaN/GaN strained layer superlattices have been employed in the cladding layers of InGaN multi-quantum well laser diodes grown by metalorganic chemical vapor deposition (MOCVD). Superlattices have been investigated for strain relief of the cladding layer, as well as an enhanced hole concentration, which is more than ten times the value obtained for bulk AlGaN films. Laser diodes with strained layer superlattices as cladding layers were shown to have superior structural and electrical properties compared to laser diodes with bulk AlGaN cladding layers. As the period of the strained layer superlattices is decreased, the threshold voltage, as well as the threshold current density, is decreased. The resistance to vertical conduction through p-type superlattices with increasing superlattice period is not offset by the increase in hole concentration for increasing superlattice spacing, resulting in higher voltages.

Download Full-text