| Summary: | 博士 === 國立成功大學 === 電機工程研究所 === 82 === In this thesis, the high luminous efficiency thin film
electroluminescent devices and the characteristics of ZnSe thin
films were investigated. The Ta2O5 and Al2O3 insulating have
high resistivity that to act as current limiter. The HfO2 and
BaTiO3 insulating have low resistivity that to act carrier
injector. Crystallinity of the ZnS:Tb,F films deposited by RF-
magnetron sputtering were studied by X-ray diffraction. The
intensive diffraction line, which arises from (111) plane of
zincblende structure, has been observed at around 28.5°. The
spacing of (111) plane and latice constant of ZnS:Tb,F film are
3.12 A and 5.41 A, respectively. In order to evalute the
interface properties of thin film electroluminescent device
with stacked layer insulator structure, four kinds of samples
with different insulating layers have been prepared. We found
that that the EL device with a glass/indium tin oxide/BaTiO3/
ZnS:TbF3/HfO2/Ta2O5/HfO2/ Al structure exhibited higher
brightness and higher efficiency than the other devices,
because it has larger density of interface states and deeper
interface states at HfO2/ZnS and BaTiO3/ZnS interfaces. The
highest luminous efficiency and brightness of 0.9 lm/W and 1000
cd/㎡ were obtained, respectively, by applying a 1Khz
sinusoidal wave viltage. The crystallinity of ZnSe thin films
grown by MOCVD, which depends on the [H2Se]/[DMZn] mole ratio
and substrate temperature was investigated. The full width at
half maximum (FWHM) of X-ray Cu-Kα (111) ZnSe diffraction
reaches the minimum value of 0.17°at optimal deposition
condition. In this experiment, the optimal growth condition of
ZnSe films are 300 ℃, 5 Torr and VI/II ratio of about 4. The
latice constant and energy gap of ZnSe thin film obtained were
5.69 A and 2.70 eV, respectively. Absorption-edge shifts
produced by an applied electric field (Franz-Keldysh) in ZnSe
thin films have been studied. As a result, the absorption edge
is shifted by about 33 meV toward longer wavelength.
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