• E2M - 전기 전자와 첨단 소재
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• 제9권2호
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• pp.152-158
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• 1996

Optical absorption and photoconductivity spectra of undoped and Co-doped Cd$_{4}$GeSe$_{6}$ single crystals, grown by the chemical transport reaction using iodine as a transporting agent, were investigated. At 20K, the optical energy gaps of the single crystals are 1.934eV for Cd$_{4}$GeSe$_{6}$ and 1.815eV for Cd$_{4}$GeSe$_{6}$ :Co$^{2+}$. The photoconductivity spectra of these single crystals were closely investigated over the temperature range 20-290K. At 20K, the photoconductivity peaks were located at 1.797eV, 1.347eV for Cd$_{4}$GeSe$_{6}$ and 1.815eV, I,.57eV, 1.46eV and 1.38eV for Cd$_{4}$GeSe$_{6}$ :Co$^{2+}$, respectively.ely.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권2호
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• pp.85-90
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• 2003

In this work $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}$ : $Co^{2+}$ single crystals were grown by the chemical transport reaction method and the structure of $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}$ : $Co^{2+}$ single crystals were monoclinic structure. The temperature dependence of optical energy 9ap was fitted well to Varshni equation. Also, the entropy, enthalpy and heat capacity were deduced from the temperature dependence of optical energy gap.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 제4회 영호남학술대회 논문집
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• pp.31-36
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• 2002

In this work $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}:Co^{2+}$ single crystals were grown by the chemical transport reaction method and the structure of $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}:Co$ single crystals were monoclinic structure. The temperature dependence of optical energy gap was fitted well to Varshni equation. Also, the entropy, enthalpy and heat capacity were deduced from the temperature dependence of optical energy gap.

• 한국진공학회지
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• 제18권6호
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• pp.459-467
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• 2009

진공증착법으로 $Cd_2GeSe_4$와 $Cd_2GeSe_4:Co^{2+}$ 박막을 ITO(indium tin oxide) 유리 기판 위에 제작하였다. 결정화는 증착된 박막들을 질소분위기의 전기로에서 열처리함으로서 이룰 수 있었다. X-선 회절 분석에 의하여 증착된 $Cd_2GeSe_4$와 $Cd_2GeSe_4:Co^{2+}$ 박막의 격자상수는 $a\;=\;7.405\;{\AA}$, $c\;=\;36.240\;{\AA}$와 $a\;=\;7.43\;{\AA}$, $c\;=\;36.81\;{\AA}$로서 능면체(rhombohedral) 구조이었고, 열처리 온도를 증가함에 따라 (113)방향으로 선택적으로 성장됨을 알 수 있었다. 열처리 온도를 증가시킴에 따라 입계 크기가 점차 커지고 판상구조로 결정화 되었다. 실온에서 측정한 광학적인 에너지 띠 간격은 열처리 온도의 증가에 따라 $Cd_2GeSe_4$ 박막의 경우 1.70 eV ~ 1.74 eV로 증가하였고, $Cd_2GeSe_4:Co^{2+}$ 박막의 경우 1.79 eV ~ 1.74 eV로 감소하였다. $Cd_2GeSe_4$와 $Cd_2GeSe_4:Co^{2+}$ 박막 내의 전하운반자들의 동역학적 거동을 광유기 방전 특성(PIDC : photoinduced discharge characteristics) 방법으로 조사하였다.

• E2M - 전기 전자와 첨단 소재
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• 제7권6호
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• pp.504-510
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• 1994

In this work the crystal structure, optical absorption and photoluminescence of Cd$_{4}$GeSe$_{6}$ single srystals grown by the vertical bridgman method are investigated. From the observed results of the PICTS, we proposed on energy band model which contains deep levels between the conduction band and the valence band. The energy band model permit us to explain the mechanism of the radiative recombination for the Cd$_{4}$GeSe$_{6}$ single crystals.als.

• 한국광학회지
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• 제8권6호
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• pp.445-449
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• 1997

비정질상과 결정상으로 가역변화하는 특성을 이용하여, 기존의 읽기전용 기록매체인 Compact Disk(CD)를 대체할 차세대 광기록매체로 주목받고 있는 Ge$_{2}$Sb$_{2}$Te$_{5}$(GST)의 상태변화에 따른 굴절율과 소광계수, 박막의 두께와 밀도 등 박막상수들을 구하였다. DC 스퍼터링방법으로 제작한 두꺼운 GST의 복소굴절율을 양자역학적 분산식을 이용한 모델링방법으로 구하고, 한편으로는 표면미시거칠기를 AFM(Atomic Force Microscopy)으로 결정한 다음, 타원해석 스펙트럼들을 수치해석적 역방계산하여 구한 복소굴절율과 비교하였다. 결정상과 비정질상일 때의 GST의 복소굴절율을 각각 구하고 이로부터 계산된 반사율을 측정된 반사율과 비교함으로써 수치해석적인 방법이 실제 GST의 복소굴절율과 더 일치하는 값ㅇㄹ 가지게 됨을 확인하였다. 이렇게 구한 GST의 복소굴절율을 기준데이터로 사용하여 실제 설계두께를 가지는 GST박막의 두께 및 표면거칠기층을 정량적으로 구하였다.다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 제4회 영호남학술대회 논문집
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• pp.25-30
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• 2002

The ternary semiconducting compounds of the $A_{4}BX_{6}$(A=Cd, Zn, Hg; B=Si, Sn, Ge; X=S, Se, Te) type exhibit strong fluorescence and high photosensitivity in the visible and near infrared ranges, so these are supposed to be materials applicable to photoelectrical devices. These materials were synthesized and single crystals were first grown by Nitsche, who identified the crystal structure of the single crystals. In this paper. author describe the undoped and $Co^{2+}$-doped $Zn_{4}SnSe_{6}$ single crystals were grown by the chemical transport reaction(CTR) method using iodine of $6mg/cm^{3}$ as a transport agent. For the crystal. growth, the temperature gradient of the CTR furnace was kep at $700^{\circ}C$ for the source aone and at $820^{\circ}C$ for the growth zone for 7-days. It was found from the analysis of x-ray diffraction that undoped and $Co^{2+}$-doped $Zn_{4}SnSe_{6}$ compounds have a monoclinic structure. The optical absorption spectra obtained near the fundamental absorption edge showed that these compounds have a direct energy gaps. These temperature dependence of the optical energy gap were closely investigated over the temperature range 10[K]~300[K]