前瞻性量子元件
Date Issued
2005-07-31
Date
2005-07-31
Author(s)
DOI
932215E002024
Abstract
The studies of this project include the molecular beam
epitaxial (MBE) growth of GaAsSb type-II quantum
well (QW) and InGaAs/InAs quantum dot (QD), and
the modulation properties of QD laser diodes. In the
first portion, GaAsSb/GaAs type-II QW lasers were
fabricated. Because of the band-bending effect, the
emission wavelength of the laser has a blue-shift as
the cavity length is shortened. We utilized this effect
to investigate the band line-up of the GaAsSb/GaAs
QW. Through a simulation based on solving the
Poisson and Schrödinger equations simultaneously for
the band structure and optical gain of GaAsSb/GaAs
QW, we found that the valence band offset ratio (Qv)
of the unstrained GaAs0.64Sb0.36/GaAs is 1.02, and the
unstrained band-gap bowing parameter of GaAsSb is
-1.31 eV. For QD lasers, we present a novel
coupled-QD structure. The structure contains two
closely coupled InAs QD layers and one InGaAs
capping layer on top QD layer. Cross-sectional TEM
images reveal that the coupled-QDs have larger size
and lower density as compared with the controlled
sample. The laser of coupled-QD structure
demonstrates longer emission wavelength and slightly
higher threshold current density than its counterpart,
which indicates the coupled-QD structure is promising
for long wavelength applications. In the portion of the
dynamic properties study, the small-signal equivalent
circuit model of quantum-dot lasers is proposed for
the first time. We use P-SPICE to simulate their
impedance and optical responses. The validity of this
model is confirmed by the well-known laser
modulation properties. Finally, spectrally resolved
dynamics of two-state lasing in QD lasers is also
experimentally demonstrated for the first time in this
study. The onset of excited-state lasing prior to
ground-state lasing is consistent with our theoretical
prediction.
Subjects
molecular beam epitaxy
Sb-based
compound semiconductor
compound semiconductor
GaAsSb quantum well
InAs quantum dot
quantum-dot laser
bowing
parameter
parameter
valence-band-offset ratio
modulation
bandwidth
bandwidth
laser equivalent circuit
two-state
phenomenon
phenomenon
Publisher
臺北市：國立臺灣大學電子工程學研究所
Type
report
File(s)![Thumbnail Image]()
Loading...
Name
932215E002024.pdf
Size
456.05 KB
Format
Adobe PDF
Checksum
(MD5):fff2a2026041693e6d1f600350d3b61f