Effects of Impurities on the Optical Properties of Quantum Dots, Wires, and Multiple Wells

1993 ◽  
Vol 325 ◽  
Author(s):  
Garneit W. Bryant
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Simple Model ◽  
Radiative Recombination ◽  
Confined Systems ◽  
Electron Hole ◽  
Model Calculations ◽  
Shallow Impurities ◽  
Impurities And Defects

AbstractIdentifying and understanding the effects of impurities and defects in quantum dots, wires, and multiple wells is important for the development of nanostructures with good optical properties. Simple model calculations are presented to show when and how shallow impurities affect the radiative recombination of confined electron-hole pairs. Results for nanostructures are compared with results for bulk systems. Qualitative differences between bulk and confined systems are described.

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

Quantum Confinement Effects on the Dielectric Constant of Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
R. Tsu ◽  
L. Ioriatti ◽  
J. F. Harvey ◽  
H. Shen ◽  
R. A. Lux
Keyword(s):  
Dielectric Constant ◽  
Porous Silicon ◽  
Size Effects ◽  
Quantum Confinement ◽  
Electrochemical Etching ◽  
Index Of Refraction ◽  
Quantum Size Effects ◽  
Quantum Size ◽  
Quantum Confinement Effects ◽  
Shallow Impurities

ABSTRACTThe reduction of the dielectric constant due to quantum confinement is studied both experimentally and theoretically. Angle resolved ellipsometry measurements with Ar- and He-Ne-lasers give values for the index of refraction far below what can be accounted for from porosity alone. A modified Penn model to include quantum size effects has been used to calculate the reduction in the static dielectric constant (ε) with extreme confinement. Since the binding energy of shallow impurities depends inversely on ε2, the drastic decrease in the carrier concentration as a result of the decrease in ε leads to a self-limiting process for the electrochemical etching of porous silicon.

Electrical and optical characterization of Er‐implanted Si: The role of impurities and defects

1993 ◽  
Vol 74 (8) ◽  
pp. 4936-4942 ◽  
Author(s):  
F. Priolo ◽  
S. Coffa ◽  
G. Franzò ◽  
C. Spinella ◽  
A. Carnera ◽  
...  
Keyword(s):  
Optical Characterization ◽  
Impurities And Defects
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