Study on Superlattice Infrared Photodetectors and Emitting Diodes
Date Issued
2002-07-31
Date
2002-07-31
Author(s)
管傑雄
DOI
902215E002024
Abstract
In this proposal, we will develop a
technique to measure the noise power of
the photocurrent to investigate the
localized states. In particular, the
associated lifetime of the free carriers with
the localized states is our primary interest.
The carrier lifetime is an important
parameter for those devices such as laser
diodes and detectors. With simple
measurement of I-V characteristics or
absorption spectrum, we can not determine
its value. However, it can be derived from
the noise power of the photocurrent in the
devices. The ratio of the photocurrent noise
power over 4eIph where Iph is the
photocurrent gives the noise current gain.
The noise current gain also equals the ratio
of the lifetime over the transit time. In
average, a free carrier passes through the
sample in a transit time. Its magnitude may
be changed with the sample length or the
applied voltage. Therefore, the lifetime
measured with the photocurrent noise is
not limited by the frequency capability of
the measurement system. This is the best
advantage of this method to measure the
carrier lifetime.
In the future three years, we will keep
going on the development of the
measurement technique of the photocurrent
noise. The devices we will investigate are
involved with the GaN bulk, quantum
wells, quantum dots, or C-base
nanostructures. For the GaN bulk, we will
study the localized states caused by the impurities and defects while for the others,
the localized states by the nanostructures.
In addition to the noise measurement, we
will also proceed the measurements of the
FTIR absorption spectrum,
photoluminescence, Raman absorption
spectrum, and step scan radiation spectrum.
Based on all the experimental results, the
lifetime can be analyzed for which of the
radiative or nonradiative transitions is
more important. In particular, the
mechanism rendering the nonradiative
transition is our primary concern. In the
future plan, all of the results derived from
this proposal will be utilized to design the
optoelectronic devices with such
nanostructures.
Subjects
localized state
nanostructure
quantum well
quantum dot
noise
measurement
measurement
Publisher
臺北市：國立臺灣大學電機工程學系暨研究所
Type
report
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