Post on 02-Jan-2016
description
PHOTOLUMINESCENT PROPERTIES OF InGaAs
QUANTUM DOT STRUCTURES
Kenneth Clark, John Colton, Matt Guerron, Dallas Smith, Scott Thalman
Brigham Young University
Haeyeon Yang
Utah State University
Quantum Dots
Grown on surface with molecular
beams
Chemically grown in solution
http://uwnews.org/uweek/article.aspx?id=42599
GaAs
InGaAs
GaAs
Dong Jun Kim et al 2008
Nanotechnology 19 47560
Photoluminescence (P.L.)E
lec
tro
n E
ner
gy
Conduction Band
Valence Band
Band Gap
e e e e e e e e ee
Spectroscopy
Detector
Monochromator
Mirror
Lenses
Focusing Lens
ChopperPower Controller
Cryostat
Lock-in Amplifier
BNC Cable
Sample
1000 1200 1400
1E-11
1E-10
1E-9
P.L. (Arbitrary Units)
Wavelength (nm)
50 mW
032607B, 3.7K, 50% Duty, 3s Tau, 780nm
The Experiment
W. Chang et al (1999 )
Quantum Dots
Wetting Layer
Indium Rich
Regions
Wavelength
Scan Results
Problem: Peaks shift giving
Inaccurate scan results.
Reason: Higher excitation energy
causes sample heating.800 1000 1200 1400
1E-11
1E-10
1E-9
160mW80mW
P.L (arb. units)
Wavelength (nm)
250mW
Laser at 780nm
Sample 032607B
230mW240mW
The Solution
Duty Cycle decreased from 50% to 8.33%
800 1000 1200 1400
1E-11
1E-10
1E-9
160mW80mW
P.L (arb. units)
Wavelength (nm)
250mW
Laser at 780nm
Sample 032607B
230mW240mW
1000 1200 1400
1E-12
1E-11
Power (Arbitrary Units)
Wavelength (nm)
120mW (889.5W/cm^2)160mW (1186W/cm^2)200mW (1482.6W/cm^2)260mW (1927.4W/cm^2)
Sample 032607B, 3K, 780nm, 8% Duty, .3s Tau Files 8,9,12,13
Less signal, meaning lower
intensity readings.
Ability to use higher
Excitation energies
In Conclusion
100nm
Yang et al., submitted to Nanoletters
These samples have strong P.L. Adjust growth technique
800 1000 1200 1400 1600 1800
0.00
0.02
0.04
0.06
0.08
0.10
P.L. (V)
Wavelength (nm)
Light Source: 780nm, 50 mW
Detector: PDF 10C
Chop: 20 Hz, 50% Duty
Spec: Grating C
Lock-in: V-mode, tau=0.3s
File 2
September 9, 2010 Sample 032607B
P.L. up to 1400nm even at
room temperature
Patterned samples