自組成氮化銦鎵量子點研究(1/3)
Date Issued
2004-07-31
Date
2004-07-31
Author(s)
DOI
922120M002006
Abstract
The results of photoluminescence (PL),
detection-energy-dependent photoluminescence
excitation (DEDPLE), excitation-energy -dependent
photoluminescence (EEDPL), and strain state
analysis (SSA) of three InGaN/GaN quantum-well
(QW) samples with silicon doping in the well, barrier
and an undoped structure are compared. The SSA
images show strongly clustering nanostructures in the
barrier-doped sample and relatively weaker
composition fluctuations in the undoped and
well-doped samples. Differences in silicon doping
between the samples give rise to the differences in
DEDPLE and EEDPL spectra, as a result of the
differences in carrier localization. Also, the PL
results provide us clues for speculating that the
S-shape PL peak position behavior is dominated by
the quantum-confined Stark effect in an undoped
InGaN/GaN QW structure.
Temperature-dependent fsec pump-probe
experiments are performed to explore the ultrafast
carrier-relaxation processes in an InGaN/GaN
quantum-well sample, in which nm-scale cluster
structures have been identified. Combining with the
time-resolved photo- luminescence results, we can
identify three stages of carrier relaxation. The
fast-decay time, ranging from several hundred fs to
one ps, corresponds to the process reaching a local
quasi-equilibrium condition, in which carriers reach a
thermal distribution within one or a few nearby
indium-rich clusters. The slow-decay time, ranging
from tens to a couple hundred ps, corresponds to the
process reaching a global quasi-equilibrium
condition, in which carriers reach a thermal
distribution among different clusters of various
potential minima. In this stage, the mechanism of
carrier transport over barriers between clusters
dominates the relaxation process. Finally, carrier
recombination dominates the relaxation process with
the carrier lifetime in the range of a few ns.
Publisher
臺北市：國立臺灣大學光電工程學研究所
Type
report
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