비정질 칼코게나이드 Ge_30Se_70 박막의 열자극 캐패시터 방전법에 의한 트랩 제한 전류

김화민 대구효성가톨릭대학교 자연과학연구소 1991 基礎科學硏究論集 Vol.5 No.-

Abatact Thermally stimulated depolarization current(TSDC) was measured by the method of thermally stimulated capacitor discharge(TSCD) in a-Ge30,Se70, film to find the trapping properties on the states in the gap. TSDC peaks observed in TSCD experi-ment consist of two parts : Ⅰ) the dielectric relaxation current Ⅱ) the trap limited currentdue to carriers thermally released from the trap. Only part Ⅱ) would yield information about trap parameters. Therfore, the pure trap limited current in this film can be obtaind by excluding the theoretical values of the dielectric relaxation current from the measu-red TSDC spectrum. In this paper we report the resurt of such experiment and the trap depth, various trapping parameters calculated from the trap limited current.

전자-선 증착기술에 의하여 성장된 CdSe 박막의 열자극 전류 측정

김화민 대구효성가톨릭대학교 자연과학연구소 1998 基礎科學硏究論集 Vol.12 No.-

To investigate the trap levels distributed within the band gap of CdSe thin films grown by the electron-beam evaporation technique, thermally stimulated current(TSC) spectra were measured. TSC spectra which were carried out under the different illumination conditions shows various changes of TSC peaks. The energy levels of these TSC peaks were calculated from the heating rate dependence of TSC spectra and the initial rising current of TSC peaks respectively and the thermal and the optical behaviors of these peaks can be enplained by the photochemical reaction model due to the dissociation of a complex trap consist of an electron-hole trap pair. On the other hand, the results of this experiment suggests that the trap level and trapping charateristic for theTSC peak originated from the chemiabsorption of oxygen on the suface of CdSe thin film which is occured over room temperature. Key words : TSC spectra, photochemical reaction, complex trap, trapping, chemiasorption

1996 년 연구실적편 : 물리학 ; 반절연성 GaAs 에서 깊은 준위들의 트랩핑 과정에 의한 광전류 Transient 와 Photosensitization 현상

김화민 대구가톨릭대학교 자연과학연구소 1996 基礎科學硏究論集 Vol.10 No.-

진공 증착된 CdTe 박막의 기판 온도에 따른 광학상수들의 변화

김화민,한상희 대구효성가톨릭대학교 자연과학연구소 1997 基礎科學硏究論集 Vol.11 No.2

The optical constants(n, k) of vacuum-evaporated CdTe thin films are determined over 400 - 2500 nm photon wavelengths. Variations of the band gap and theoptical constants with substrate temperatures are studied. It is explained that the variations of the optical constants is close related to the changes of the surface morphology. The surface microstructural parameters for the CdTe thin films are investigated by AFM(atomic forced microscope) images and X-ray deffraction patterns. The dispersion of refractive index in films is stdudied by considering a single-oscillatormodel.

기초과학연구논집 - 1995 년 연구실적편 - / 물리학 : 비정질 As2S3 박막에 대한 Ag 광도핑 현상에 관한 연구

김화민 대구가톨릭대학교 자연과학연구소 1995 基礎科學硏究論集 Vol.9 No.-

도우핑되지 않은 반절연성 GaAs 에서의 EL2 와 다른 결함들에 의한 광전류 전이 효과들

김화민,박승환 대구효성가톨릭대학교 자연과학연구소 1994 基礎科學硏究論集 Vol.8 No.-

Photocurrent transient effects in undoped semi -insulating GaAs havebeen explained by the various conflict models. The photocurrent effects such as photocurrent quenching(PCQ), enhanced photocurrent(EPC), and persistant photocurrent(PPC) effects are reviewed and new results on these effects are reported. A comparison of the photocurrent transients with thermally stimulated current(TSC) spectra along with other experiments shows that the PCQ is due to the metastable transformation of deep donor EL2 and that the EPC and PPC ef-fects due to a separate effect that is most likely a metastable transformation of another defect. This new metastable state is responsible for the EPC and PPC recovers prior to the recovery of the metastable state of EL2 by thermal recovery experiments. The photocurrent transient experiment on the annealed samples are presentedshowing that the EPC and PPC effects are significantly reduced after anneals at the temperature range of 500℃ -650℃, well bellow the annealing temperature of quenchable EL2. This result means that only the metastability of EL2 is not sfficient to explain the EPC/PPC effects. After reviewing existing models we suggest that the shallow acceptor impurities in samples not showing the EPC after EL2 quenching are compensated by the doubly charged second level of EL2. A compex defect, perhaps including EL6 as an intermediary, is proposed for defect responsible for the charge transfer resulting in the EPC and PPC efects.

플라스틱 기판의 Outgassing이 TCO 박막의 전기적 특성에 미치는 영향

김화민,지승훈,Kim, Hwa-Min,Ji, Seung-Hun 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.11

In this work, transparent conductive oxide(TCO) films such as $In_2O_3-SnO_2$(ITO) and $In_2O_3-ZnO$(IZO) were prepared on polyethylene naphthalene(PEN) and glass substrates by using rf-magnetron sputtering system. The TCO films deposited on PEN substrate show very poor conductivity as compared to that of the TCO films deposited on glass substrates. From the results of the residual gas analysis(RGA) test, this poor stability of plastic substrate is presumed to be caused by the deteriorated adhesion between the TCO films and the plastic substrate due to outgassing from the plastic substrate during deposition of TCO films. From our experiment, it is found that the vaporization of some defects in the plastic substrates deteriorate the adhesion of the TCO films to the plastic substrate, because the most plastic substrates containing the water vapor and/or other adsorbed particles such as organic solvents. Mixing of these gases vaporized in the sputtering process will also affect the electrical property of the deposited TCO films. Inorganic thin composite $(SiO_2)_{40}(ZnO)_{60}$ film as a gas barrier layer is coated on the PEN substrate to protecting the diffusion of vapors from the substrate, so that the TCO films with an improved quality can be obtained.

Enhanced Hydrophilic Property of TiO2 Thin Film Deposited on Glass Etched with O2 Plasma

김화민,서성보,김동영,배강,손선영 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.3

TiO2 films were deposited on glass substrates with and without O2 plasma etching by using the RF-magnetron sputtering method. We focused on the effect of surface structure on the photoinduced hydrophilic properties of TiO2films, fabricated on different surface conditions according to the presence or absence of the O2 plasma treatment on glass substrates. The wettability and photoinduced hydrophilic properties of the TiO2 films were investigated according to the changes in water contact angles under UV light irradiations with a very low intensity of 0.1 mW/cm2. The photoinduced hydrophilic properties on the TiO2 formed above the plasma treated glass were also superior to those on the TiO2 formed above the bare glass. This enhanced TiO2 film has been used practically for self cleaning and anti-fogging glasses.

자기 또는 타인을 위한 결정에서 결정 수혜자에 대한 선택책임감과 해석수준이 위험감수 정도에 미치는 영향

김화민 한국소비자·광고심리학회 2019 한국심리학회지 소비자·광고 Vol.20 No.3

Among the many decisions made throughout the day is not only for myself, but also for others. In the same situation, however, who is the beneficiary of the decision may affect the outcome of the decision. This study is to examine how the decision beneficiary affect the decision process. In particular, the effect of decision object and construal levels on risk-taking. In addition, it was intended to examine the effect of choice accountability on the decision maker by comparing it with the decision maker's accountability to explain its decision to the beneficiary of the decision. In this study, the effect of decision object and construal levels on risk-taking levels has been examined. Each participant was randomly assigned to one of six conditions in the experimental of 3(decision object: self/other with accountability/ without accountability) X 2(construal level: high/low) 2-way completely randomized factorial design. The result shows an effect of correlation between decision object and construal level, and represents that participants who have low-construal prefer to select low risk-taking choices when the decisions are made for self and for other with responsibility, whereas participants who have high-construal reveal not much difference. Although it is very common to decide whether to take or avoid risks in various circumstances, this study focuses on consumers' decision making upon purchase. Especially, a decision making procedure upon purchasing items for oneself or for others has been investigated with the consideration of the others classified by detailed characteristics. The research results implicate that people have a tendency to take higher risks for the choices for others than for themselves but the tendency diminishes when they feel accountabilities. Through the measurement of construal levels, it has been identified that individuals' variable also has an influence on the results. 하루 동안에도 끊임없이 이루어지는 여러 결정들 중에는 나 자신만을 위한 결정 뿐 아니라, 타인을 위한 결정도 있다. 그런데 동일한 상황이라도 결정의 수혜자가 누구인지가 결정의 결과에 영향을 미칠 수 있다. 본 연구에서는 결정의 수혜자가 결정과정에 미치는 영향을 살펴보고자 하였다. 더 나아가, 결정자의 성향과 결정 시의 상황도 결정에 영향을 미칠 것이다. 이에 따라 본 연구에서는 결정자의 성향 중 해석수준이 미치는 영향에 대해서 살펴보았다. 또한, 결정자가 처한 상황 중 결정자가 결정수혜자에게 자신의 결정에 대해 설명하는 것에 대한 책임감을 느끼는 경우와 그렇지 않은 경우를 비교하여 살펴봄으로써 선택책임감이 결정자에게 미치는 영향을 살펴보고자 하였다. 연구 결과, 하위해석자는 상위해석자에 비해 타인에 대해 선택책임감을 느끼는지 여부에 영향을 더 많이 받는 것으로 나타났다. 하위해석자는 자기를 위한 결정을 할 때와 선택책임감을 느끼지 않는 타인을 위한 선택을 할 때에는 상위해석자보다 위험을 감수하지 않으려고 하지만, 타인에 대해 선택책임감을 느끼지 않을 때에는 위험을 감수하려고 하는 정도가 크게 증가하는 것으로 확인되었다. 이와 같은 연구의 결과는 구매결정상황에도 시사하는 바가 크다고 할 수 있다. 예를 들어서, 자기 자신을 위해서도 가입하지 않을 수 있는 보험 상품도 타인을 위해 결정해야 하는 상황에서 보다 책임감을 느끼도록 한다면 가입 가능성이 높아질 수 있기 때문이다. 반면, 이 연구에서 책임감을 조작한 방식은 결정자가 결정의 결과에 대한 실질적인 책임을 느낄 수 있도록 조작되지는 않았다는 점에서 책임감의 역할을 제한적으로 살펴보았다는 한계를 가진다. 따라서 보다 광범위하게 책임감의 역할을 살펴볼 수 있는 다양한 후속 연구를 통하여 책임감이 결정자에 미치는 영향을 보다 상세하게 규명할 필요가 있다.

Homogeneous Multi-layered Films of SiOx and SiOxNy Deposited on PEN by Using a Facing Target Sputtering System for Passivation of Organic Light Emitting Diodes

김화민,손선영,배강 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.6

Homogeneous multi-layered barrier films of SiOx and SiOxNy were fabricated from the same Sitarget by means of a reactive process using a facing target sputtering (FTS) system. The multi-layerfilms gave 35% improved barrier performance and the fabrication process was 70% faster that thefor with single SiOxNy layers of the same thickness. The water vapor transmission rate was reducedto the order of 10−4 g m−2day−1 for a three-pair system of SiOxNy/SiOx bilayers.