산소 유량비 변화에 따른 Al 도핑된 ZnO 박막의 구조 및 광학적 특성

손영국,황동현,조신호,Son, Young-Gook,Hwang, Dong-Hyun,Cho, Shin-Ho 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.4

라디오파 마그네트론 스퍼터링 방법으로 유리 기판 위에 Al 도핑된 ZnO (AZO) 박막을 성장시켰다. 증착시 스퍼터링 가스로 사용하는 산소 유량비의 변화에 따른 AZO 박막의 특성을 X-선 회절법, 원자 주사 현미경, 홀 효과 측정법으로 조사하였다. 증착 온도 $400^{\circ}C$에서 산소 유량비 0%로 증착된 AZO 박막은 가장 큰 c-축 우선 배향성과 최저의 비저항값 $6.9{\times}10^{-4}{\Omega}cm$을 나타내었다. 산소 유량비가 증가함에 따라 ZnO (002)면의 회절 피크의 세기는 실질적으로 감소하는 경향을 보였다. 또한, 산소 유량비가 감소함에 따라 전하 운반자의 농도와 홀 이동도는 증가하였으나, 전기 비저항은 감소하였다. Al-doped ZnO (AZO) thin films were grown on glass substrates by radio-frequency magnetron sputtering. The effects of oxygen flow ratio, which was used for a sputtering gas, on the AZO thin films were investigated by using the X-ray diffraction (XRD), atomic force microscopy (AFM), and Hall effects measurement. The AZO thin film, deposited with oxygen flow ratio of 0% at the growth temperature of $400^{\circ}C$, showed a strongly c-axis preferred orientation and the lowest resistivity of $6.9{\times}10^{-4}{\Omega}cm$. The ZnO (002) diffraction peak indicated a tendency to decrease substantially with increasing the oxygen flow ratio. Furthermore, as the oxygen flow ratio was decreased, the carrier concentration and the hall mobility were increased, but the electrical resistivity was decreased.

Al 도핑된 ZnO 박막에서 방출되는 보라색 발광 스펙트럼

황동현,손영국,조신호,Hwang, Dong-Hyun,Son, Young-Guk,Cho, Shin-Ho 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.4

We report on a strong violet luminescence emitted from the ZnO:Al films grown on glass substrate by radio-frequency magnetron sputtering. The growth of high-quality thin films and their optical properties are controlled by adjusting the mixture ratio of Ar and $O_2$, which is used as the sputtering gas. The crystallinity of the films is improved as the oxygen flow ratio is decreased, as evidenced in both x-ray diffractometer and atomic force microscope measurements. As for the violet luminescence measured by photoluminescence (PL) spectroscopy, the peak energy and intensity of the PL signal are decreased with increasing the oxygen flow ratio. The peak energy of the violet PL spectrum for the thin film with an oxygen flow ratio of 50 % is almost constant, regardless of the increase of laser Power and temperature. These results indicate that the violet PL signal is probably due to defects related to interstitial Zn atoms.

R.F. Magnetron Sputtering을 이용한 리튬이차전지 부극용 Sn_1-xSi_xO₂의 제조 및 특성

이상헌,박건태,손영국,Lee, Sang-Heon,Park, Keun-Tae,Son, Young-Guk 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.4

리튬 이차전지용 부극재료로 미량의 실리콘이 첨가된 주석산화물 박막을 R.F. magnetron sputtering법을 이용하여 제조하였다. 실리콘의 첨가로 인해 주석의 산화상태를 감소시켜서 첫 번째 충방전 동안 비가역성을 감소시키는 전기 화학적 결과를 얻을 수 있었다. 주석 산화물 박막의 결정 배향성은 기판온도가 올라감에 따라서 (110),(101),(211) 면들이 성장하였다. 합성된 박막은 기판온도가 $300^{\circ}C$이고 $Ar:O_2$의 비가 7:3일때, 700mAh/g의 에너지 밀도를 가지며 가장 좋은 가역성능을 보여주었다. Tin oxide thin films doped with silicon as anodes for lithium secondary battery were fabricated by R. F. magnetron sputtering technique. The electrochemical results for lithium secondary battery anodes showed that addition of silicon decreases the oxidic state of tin, and, hence, reduced the irreversible capacity during the first discharge/charge cycle. The (110),(101),(211) planes were grown with increasing substrate temperatures. The reversible capacity of thin films fabricated in conditions of $300^{\circ}C$ substrate temperature and 7:3 $Ar:O_2$ ratio was 700 mAh/g.

실리콘을 첨가한 주석 산화물 박막의 전기 화학적 특성

이상헌,박건태,손영국,Lee, Sang-Heon,Park, Geon-Tae,Son, Yeong-Guk 한국재료학회 2002 한국재료학회지 Vol.12 No.4

Tin oxide thin films doped with silicon as anodes for lithium secondary battery were fabricated by R.F. magnetron sputtering technique. The electrochemical results showed that the irreversible capacity was reduced during the first discharge/charge cycle, because the audition of silicon decreased the oxidic state of Tin. Capacity was increased with the increase of substrate temperature, however decreased with the increase of RTA temperatures. The reversible capacity of thin films fabricated under the substrate temperature of $300^{\circ}C$ and the Ar:$O_2$ratio of 7:3 was 700mA/g.

ZrO₂ 완충층과 SBT박막을 이용한 MFIS 구조의 제조 및 전기적 특성

김민철,정우석,손영국,Kim, Min-Cheol,Jung, Woo-Suk,Son, Young-Guk 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.4

Metal-Ferroelectric-Insulator-Semiconductor(MFIS) 구조의 적용하기 위해 R. F. 마그네트론 스퍼터를 이용하여 p-type Si(111) 기판 위에 $ZrO_2$와 $SrBi_2Ta_2O_9$ 박막을 증착하였다. SBT 박막은 $ZrO_2$ 완충층을 삽입함으로써 MFIS 구조의 전기적인 특성이 향상되었다. $ZrO_2$ 박막의 두께를 고정하고 SBT 박막의 두께를 160nm에서 220nm으로 변화시키면서 윈도우 메모리를 3-9V의 범위에서 측정하였다. Pt/SBT(160nm)/$ZrO_2$(20nm)/Si의 조건에서 최대 2.2V 메모리 윈도우 값을 얻을 수 있었으며 이 메모리 윈도우 값은 실제 적용되는 저전압 NDRO-FRAM 구동에 충분한 값이다. The possibility of $ZrO_2$ thin film as insulator for Metal-Ferroelectric-Insulator-Semiconductor(MFIS) structure was investgated. $SrBi_2Ta_2O_9$ and $SrBi_2Ta_2O_9$(SBT) thin films were deposited on P-type Si(111) wafer by R. F. magnetron sputtering method. The electrical properties of MFIS gate were relatively improved by inserting the $ZrO_2$ buffer layer. The window memory increased from 0.5 to 2.2V in the applied gate voltage range of 3-9V when the thickness of SBT film increased from 160 to 220nm with 20nm thick $ZrO_2$. The maximum value of window memory is 2.2V in Pt/SBT(160nm)/$ZrO_2$(20nm)/Si structure with the optimum thickness of $ZrO_2$. These memory windows are sufficient for practical application of NDRO-FRAM operating at low voltage.

R.F. Magnetron Sputtering으로 다양한 Interlayer 층위에 형성시킨 PZT 박막의 미세구조와 강유전 특성

박철호,최덕영,손영국,Park, Chul-Ho,Choi, Duck-Young,Son, Young-Guk 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.8

R. F. magnetron sputtering법을 이용하여 Pt/Ti/$SiO_2$/Si 기판 위에 $Pb_{1.1}Zr_{0.53}Ti_{0.47}O_3$ target을 사용하여 박막을 제조하였다. Interlayer(PbO, $TiO_2$, PbO/$TiO_2$)층을 삽입함으로써 박막의 결정성을 향상시켰고, 박막의 기판온도도 상당히 낮출 수 있었다. 순수한 PZT에 비하여 interlayer를 삽입한 PZT는 높은 유전상수과 낮은 유전손실 및 높은 누설전류를 가지는 우수한 전기적 특성을 나타내었다. 이러한 PZT 박막과 interlayer 층은 증착온도에서 서로 반응하여 하나의 고용체를 이루지 않고, 각각 독립적인 층으로 존재함을 XPS 분석을 통해 확인하였다. 여러 interlayer중 특히 PbO/$TiO_2$는 우수한 유전특성(${\varepsilon}_r$=414.94, tan${\delta}$=0.0241, Pr=22${\mu}C/cm^2$)을 나타내었고 가장 효과적인 seed로써의 역할을 하였다. The PZT thin films werre deposited on Pt/Ti/$SiO_2$/Si substrate by R. F. magnetron sputtering with $Pb_{1.1}Zr_{0.53}Ti_{0.47}O_3$ target. When interlayers(PbO, $TiO_2$, PbO/$TiO_2$) were inserted between PZT and Pt, the crystallization of the PZT thin films was considerably improved and the processing temperature was lowered. Compared to the pure PZT thin films, dielectric constant, dielectric loss and polarization properties of PZT thin films with interlayers were considerably improved. From XPS depth profile analysis, it was confirmed that PZT thin films and interlayers existed independently. In particular, PZT thin films deposited on interlayer(PbO/$TiO_2$) showed the best dielectric property (${\varepsilon}_r$=414.94, tan${\delta}$=0.0241, Pr=22${\mu}C/cm^2$).

기판온도가 ZnS 박막의 구조 및 광학적 특성에 미치는 영향

황동현,안정훈,손영국,Hwang, Dong-Hyun,Ahn, Jung-Hoon,Son, Young-Guk 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.9

Znic sulfide (ZnS) thin films were deposited on glass substrates by radio frequency magnetron sputtering. The substrate temperature varied from room temperature (RT) to $500^{\circ}C$. The structural and optical properties of ZnS films were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive analysis of X-ray (EDAX) and UV-visible transmission spectra. The XRD analyses reveal that ZnS films have cubic structures with (111) preferential orientation, whereas the diffraction patterns sharpen with the increase in substrate temperatures. The FESEM images indicate that ZnS films deposited at $400^{\circ}C$ have nano-sized grains with a grain size of ~ 67 nm. Then films exhibit relatively high transmittance of 80% in the visible region, with an energy band gap of 3.71 eV. One obvious result is that the energy band gap of the film increases with increasing the substrate temperatures.

PbO 완충층을 이용한 Pt/Pb_1.1Zr_0.53Ti_0.47O₃/PbO/Si (MFIS)의 미세구조와 전기적 특성

박철호,송경환,손영국,Park, Chul-Ho,Song, Kyoung-Hwan,Son, Young-Guk 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.2

PbO 완충층의 역할을 확인하기 위해, r.f. magnetron sputtering법을 이용하여 p-type (100) Si 기판 위에 $Pt/Pb_{1.1}Zr_{0.53}Ti_{0.47}O_{3}$와 PbO target으로 Pt/PZT/PbO/Si의 MFIS 구조를 제조하였다. MFIS 구조에 완충층으로 PbO를 삽입함으로써 PZT 박막의 결정성이 크게 향상되었고, 박막의 공정온도도 상당히 낮출 수 있었다. 그리고 XPS depth profile 분석 결과, PbO 증착시 기판온도가 PbO와 Si의 계면에서 Pb의 확산에 미치는 영향을 확인하였다. PbO 완충층을 삽입한 MFIS는 높은 메모리 윈도우와 낮은 누설전류 밀도를 가지는 추수한 전기적 특성을 나타내었다. 특히, 기판온도 $300^{\circ}C$에서 증착된 PbO를 삽입한 Pt/PZT(200nm, $400^{\circ}C)PbO(80nm)/Si$는 9V의 인가전압에서 2.OV의 가장 높은 메모리 윈도우 값을 나타내었다. To study the role of PbO as the buffer layer, Pt/PZT/PbO/Si with the MFIS structure was deposited on the p-type (100) Si substrate by the r.f. magnetron sputtering with $Pb_{1.1}Zr_{0.53}Ti_{0.47}O_3$ and PbO targets. When PbO buffer layer was inserted between the PZT thin film and the Si substrate, the crystallization of the PZT thin films was considerably improved and the processing temperature was lowered. From the result of an X-ray Photoelectron Spectroscopy (XPS) depth profile result, we could confirm that the substrate temperature for the layer of PbO affects the chemical states of the interface between the PbO buffer layer and the Si substrate, which results in the inter-diffusion of Pb. The MFIS with the PbO buffer layer show the improved electric properties including the high memory window and low leakage current density. In particular, the maximum value of the memory window is 2.0V under the applied voltage of 9V for the Pt/PZT(200 nm, $400^{\circ}C)/PbO(80 nm)/Si$ structures with the PbO buffer layer deposited at the substrate temperature of $300^{\circ}C$.

Self-seed layer를 이용하여 증착한 SBT박막의 특성

김형섭,황동현,윤지언,손영국,Kim, Hyung-Sub,Hwang, Dong-Hyun,Yoon, Ji-Un,Son, Young-Gook 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.3

[ $Pt/SBT/Seed/Pt/Ti/SiO_2/Si$ ]의 구조로 $SBT(SrBi_2Ta_2O_9)$ 박막을 Self-seed layer를 사용하여 R.F. Magnetron sputter를 이용하여 증착을 하였다. Self-seed layer는 기판온도 RT(room temperature)와 $600^{\circ}C$에서 두께 30 nm으로 증착하였다. Self-seed layer의 결정화 온도를 알아보기 위해 열처리온도를 변화시켰고 이를 XRD를 통하여 결정화 유무를 확인하였다. Self-seed layer 위에 증착한 SBT를 XRD와 전기적 측정을 통해 특성을 관찰하였다. Thin films of $SBT(SrBi_2Ta_2O_9)$ having $Pt/SBT/Seed/Pt/Ti/SiO_2/Si$ structure were fabricated using self-seed layer method by R.F. Magnetron sputter. Self-seed layers were deposited at room temperature and $600^{\circ}C$, which had 30 nm thickness. To investigate crystallization of self-seed layer we characterized by XRD after various heat treatment. And we characterized the crystallinity and electrical properties of SBT on self-seed layer after various heat treatment.

기판온도에 따른 PLZT 박막의 결정성과 전기적 특성

이인석,윤지언,김상지,손영국,Lee, In-Seok,Yoon, Ji-Eun,Kim, Sang-Jih,Son, Young-Guk 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.1

PLZT thin films were deposited on platinized silicon (Pt/$TiSiO_2$/Si) substrate by RF magnetron sputtering. A $TiO_2$ buffer layer was fabricated, prior to deposition of PLZT films. the layer was strongly affected the crystallographic orientation of the PLZT films. X-ray diffraction was performed on the films to study the crystallization of the films as various substrate temperatures (Ts). According to increasing Ts, preferred orientation of films was changed (110) plane to (111) plane. The ferroelectric, dielectric and electrical properties of the films were also investigated in detail as increased substrate temperatures. The PLZT films deposited at $400^{\circ}C$ showed good ferroelectric properties with the remnant polarization of $15.8{\mu}C/cm^2$ and leakage current of $5.4{\times}10^{-9}\;A/cm^2$.