Structural, Optical and Photoconductive Properties of Chemically Deposited Nanocrystalline CdS Thin Films

박욱동 한국전기전자재료학회 2011 Transactions on Electrical and Electronic Material Vol.12 No.4

Nanocrystalline cadmium sulphide (CdS) thin films were prepared using chemical bath deposition (CBD), and the structural, optical and photoconductive properties were investigated. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size, dislocation density and lattice constant of CBD CdS thin films were investigated. The dislocation density of CdS thin films initially decreases with increasing film thickness, and it is nearly constant over the thickness of 2,500 Å. The dislocation density decreases with increasing the crystallite size. The Urbach energies of CdS thin films are obtained by fitting the optical absorption coefficient. The optical band gap of CdS thin films increases and finally saturates with increasing the lattice constant. The Urbach energy and optical band gap of the 2,900 Å-thick CdS thin film prepared for 60 minutes are 0.24 eV and 2.83 eV, respectively. The activation energies of the 2,900 Å-thick CdS thin film at low and high temperature regions were 14 meV and 31 meV, respectively. It is considered that these activation energies correspond to donor levels associated with shallow traps or surface states of CdS thin film. Also, the value of γ was obtained from the light transfer characteristic of CdS thin film. The value of γ for the 2,900 Å-thick CdS thin film was 1 at 10 V, and it saturates with increasing the applied voltage.

Optical Constants and Dispersion Parameters of CdS Thin Film Prepared by Chemical Bath Deposition

박욱동 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.4

CdS thin film was prepared on glass substrate by chemical bath deposition in an alkaline solution. The optical properties of CdS thin film were investigated using spectroscopic ellipsometry. The real (ε1) and imaginary (ε2) parts of the complex dielectric function ε(E)=ε1(E) + iε2(E), the refractive index n(E), and the extinction coefficient k(E) of CdS thin film were obtained from spectroscopic ellipsometry. The normal-incidence reflectivity R(E) and absorption coefficient α(E) of CdS thin film were obtained using the refractive index and extinction coefficient. The critical points E0 and E1 of CdS thin film were shown in spectra of the dielectric function and optical constants of refractive index,extinction coefficient, normal-incidence reflectivity, and absorption coefficient. The dispersion of refractive index was analyzed by the Wemple-DiDomenico single-oscillator model.

영상센서를 위한 a-Si : H 광다이오드의 제작 및 특성

박욱동,김기완 ( Wug Dong Park,Ki Wan Kim ) 한국센서학회 1993 센서학회지 Vol.2 No.1

a-Si : H photodiodes for image sensor have been fabricated and characterized. Photosensitivity of a ITO/a-Si : H/Al photodiode without blocking layer was 0. 7 under the applied voltage of 5 V and peak spectral sensitivity in visible region was found at 620 nm. Dark current of ITO/a-SiN : H/a-Si : H/p-a-Si : H/Al photodiode was suppressed by hole blocking layer and electron blocking layer at the value of lower than 1.5 pA to the applied voltage of 10 V. Also maximum photosensitivity was about 1 under the applied voltage of 3 V and peak spectral sensitivity was found at 540 nm.

Photoluminescence of Nanocrystalline CdS Thin Films Prepared by Chemical Bath Deposition

박욱동 한국전기전자재료학회 2010 Transactions on Electrical and Electronic Material Vol.11 No.4

Nanocrystalline cadmium sulfide (CdS) thin films were prepared using chemical bath deposition in a solution bath containing CdSO4, SC(NH2)2, and NH4OH. The CdS thin films were investigated using X-ray diffraction (XRD), photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). The as-deposited CdS thin film prepared at 80°C for 60 min had a cubic phase with homogeneous and small grains. In the PL spectrum of the 2,900 Å-thick CdS thin film, the broad red band around 1.7 eV and the broad high-energy band around 2.7 eV are attributed to the S vacancy and the band-to-band transition, respectively. As the deposition time increases to over 90 min, the PL intensity from the band-to-band transition significantly increases. The temperature dependence of the PL intensity for the CdS thin films was studied from 16 to 300 K. The EA and EB activation energies are obtained by fitting the temperature dependence of the PL intensity. The EA and EB are caused by the deep trap and shallow surface traps, respectively. From the FTIR analysis of the CdS thin films, a broad absorption band of the OH stretching vibration in the range 3,000-3,600 cm-1 and the peak of the CN stretching vibration at 2,000 cm-1 were found.

고휘도 ZnS:Mn 박막전계발광소자의 제조 및 특성

박욱동 동양대학교 1995 동양대학교 논문집 Vol.1 No.1

진공증착법으로 제조된 ZnS:Mn 박막의 증착률은 기판온도가 증가함에 따라 감소하였다.200℃ 기판온도에서 증착된 ZnS:Mn 박막은 (111) 방향으로 결정화되었으며 ZnS:Mn 박막의 광학적 밴드갭은 약 3.3 eV로 나타났다.진공증착법에 의해 증착된 ZnS:Mn 형광층과 RF 마그네트론 스퍼터링법으로 형성된 PLT 절연층으로 박막전계발광소자를 제조하였다.ZnS:Mn 형광층 및 PLT 절연층의 두께를 각각 6000 Å 및 1000 Å으로 한 박막전계발광소자는 3 kHz의 구동주파수에서 50 Vrms의 발광문턱전압을 나타내었으며 74 Vrms의 인가전압에서 박막전계발광소자의 휘도는 250 μW/cm2 였다. The deposition rate of ZnS:Mn thin film deposited by vacuum evaporation method was decreased by increasing substrate temperature.ZnS:Mn thin film at substrate temperature of 200 ℃ was crystallized on (111) direction and the optical bandgap of ZnS:Mn thin film was 3.3 eV.Thin film electroluminescent(TFEL) devices have been fabricated using ZnS:Mn phosphor deposited by vacuum evaporation method and PLT insulator prepared by RF magnetron sputtering method.The TFEL device using ZnS:Mn(6000 Å) and PLT(1000 Å) thin films showed the threshold voltage of 50 Vrms at the driving frequency of 3 kHz.The brightness of TFEL device was 250 μW/cm2 at the applied voltage of 74 Vrms.

ZnS:Mn 형광층을 이용한 ACTFEL소자의 제조 및 특성

박욱동 동양대학교 1999 동양대학교 논문집 Vol.5 No.1

ACTFEL(AC thin film electroluminescent)소자의 형광층을 위해 기판온도 200℃에서 진공증착된 ZnS:Mn 박막을 AES표면분석한 결과 Zn과 S의 비는 1:1정도로 나타났다. 또한 ZnS:Mn 박막의 광학적 밴드갭은 3.3eV였으며 PL측정결과 580nm의 파장에서 최대값을 나타내었다. 이 결과로부터 ZnS:Mn 형광체의 발광중심으로 작용하는 Mn2+이온은 전도대로부터 1.16ev정도 낮은 준위에 존재함을 알 수 있었다. ZnS:Mn 형광층 및 PLT 절연층을 이용한 유리/ITO/ZnS:Mn/PLT/Al 구조로 제조된 ACTFEL 소자의 휘도는 100V의 인가전압에서 2,500cd/m2였다. A ratio of Zn : S of a ZnS:Mn thin film deposited by vacuum evaporation method at 200℃ for a phosphor layer of an ACTFEL device was 1:1 by the AES surface analysis. An optical bandgap of a ZnS:Mn thin film was 3.3eV and the maximum intensity of PL spectrum was at a wavelength of 580nm. From these results, it was found that the energy level of Mn2+ ion as the recombination center of a ZnS:Mn phosphor was located at the low level of 1.16eV from the conduction band. The brightness of an ACTFEL device which have a structure of glasss/ITO/ZnS:Mn/PLT/Al using the ZnS:Mn phosphor and PLT insulator was 2,500cd/m2 at 100V.

밀착형 이미지 센서의 정공 차단층을 위한 a-SiN:H막의 제조 및 특성

박욱동,오상광,남기홍,김기완 경북대학교 센서기술연구소 1992 센서技術學術大會論文集 Vol.3 No.1

ZnS:SmF₃박막전계발광소자의 제작 및 특성

박욱동,배승춘,김기완 동양대학교 산업기술연구소 2000 東洋大學校 産業技術硏究所 論文集 Vol.2 No.1

A red colored thin film electroluminescent(TFEL) device was fabricated with a ZnS:SmF3 phosphor layer and BST insulating layers. The BST thin film was deposited on ITO coated glass substrate by RF magnetron sputtering method using a target of Ba0.5Sr0.5TiO3. The thickness of ZnS:SmF3 thin film, upper and lower BST insulating layer for a TFEL device were 500nm, 400nm, and 200nm, respectively. The ZnS:SmF3 TFEL device showed that the threshold voltage and maximum brightness of a TFEL device were 160Vrms and 125cd/㎡, respectively.

PLT 절연층을 이용한 ZnS:Mn TFEL소자의 제조 및 특성

박욱동,박경빈,박재현,김영진,최병진,김기완 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1

Thin film electroluminescent(TFEL) device has been fabricated using ZnS:Mn phosphor and PLT insulator. The ZnS:Mn and PLT thin film for TFEL device was deposited by vacuum evaporation method and RF magnetron sputtering method, respectively. The TFEL device using ZnS:Mn(6000 Å) and PLT(1000 Å) thin films showed the threshold voltage of 50 Vrms at the driving frequency of 3 kHz. The brightness of TFEL device was 250 μW/cm^(2) at the applied voltage of 74 Vrms. Also the output current of TFEL device was linearly increased with applied voltage.

PECVD법에 의한 비정질 실리콘 질화막의 제조 및 특성

박욱동,김영진,배승춘,이경하,김기완 한국진공학회 1994 한국진공학회 학술발표회초록집 Vol.- No.-