Structural Analyses of Phase Stability in Amorphous and Partially Crystallized Ge-Rich GeTe Films Prepared by Atomic Layer Deposition

Gwon, Taehong,Mohamed, Ahmed Yousef,Yoo, Chanyoung,Park, Eui-sang,Kim, Sanggyun,Yoo, Sijung,Lee, Han-Koo,Cho, Deok-Yong,Hwang, Cheol Seong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.47

<P>The local bonding structures of GexTe1-x (x = 0.5, 0.6, and 0.7) films prepared through atomic layer deposition (ALD) with Ge(N(Si(CH3)(3))(2))(2) and ((CH3)(3)Si)(2)Te precursors were investigated using Ge K-edge X-ray absorption spectroscopy (XAS). The results of the X-ray absorption fine structure analyses show that for all of the compositions, the as-grown films were amorphous with a tetrahedral Ge coordination of a mixture of Ge-Te and Ge-Ge bonds but without any signature of Ge-GeTe decomposition. The compositional evolution in the valence band electronic structures probed through X-ray photoelectron spectroscopy suggests a substantial chemical influence of additional Ge on the nonstoichiometric Ge-Te. This implies that the ALD process can stabilize Ge-abundant bonding networks like Te-Ge-Ge-Te- in amorphous GeTe. Meanwhile, the XAS results on the Ge-rich films that had undergone post-deposition annealing at 350 degrees C show that the parts of the crystalline Ge-rich GeTe became separated into Ge crystallites and rhombohedral GeTe in accordance with the, bulk phase diagram, whereas the disordered GeTe domains still remained, consistent with the observations of transmission electron microscopy and Raman spectroscopy. Therefore, amorphousness in GeTe may be essential for the nonsegregated Ge-rich phases and the low growth temperature of the ALD enables the achievement of the structurally metastable phases.</P>

Ab Initio Study of Mechanism of Forming Spiro-Ge-Heterocyclic Ring Compound From Cl2Ge=Ge: and Formaldehyde

Xiuhui Lu,Yongqing Li,Jingjing Ming 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.12

The H2Ge=Ge: and its derivatives (X2Ge=Ge:, X = H, Me, F, Cl, Br, Ph, Ar……) is a new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of the cycloaddition reaction between singlet state Cl2Ge=Ge: and formaldehyde has been investigated with CCSD(T)//MP2/6-31G* method. From the potential energy profile, it could be predicted that the reaction has only one dominant reaction pathway. The reaction rule presented is that the two reactants first form a fourmembered Ge-heterocyclic ring germylene through the [2+2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge: atom in the four-membered Ge-heterocyclic ring germylene and the π orbital of formaldehyde forming a π→p donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge: atom in intermediate hybridizes to an sp3 hybrid orbital after transition state, then, intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. The research result indicates the laws of cycloaddition reaction between H2Ge=Ge: and formaldehyde, and laid the theory foundation of the cycloaddition reaction between H2Ge=Ge: and its derivatives (X2Ge=Ge:, X = H, Me, F, Cl, Br, Ph, Ar……) and asymmetric π-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds. The study extends research area and enriches the research content of germylene chemistry.

Si_1-xGe_x 층의 건식산화 동안 Ge 재 분포와 상호 확산의 영향

신창호,이영훈,송성해,Shin, Chang-Ho,Lee, Young-Hun,Song, Sung-Hae 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.12

We have studied the Ge redistribution after dry oxidation and the oxide growth rate of $Si_{1-x}Ge_x$ epitaxial layer. Oxidation were performed at 700, 800, 900, and $1,000\;^{\circ}C$. After the oxidation, the results of RBS (Rutherford Back Scattering) & AES(Auger Electron Spectroscopy) showed that Ge was completely rejected out of the oxide and pile up at $Si_{1-x}Ge_x$ interface. It is shown that the presence of Ge at the $Si_{1-x}Ge_x$ interface changes the dry oxidation rate. The dry oxidation rate was equal to that of pure Si regardless of Ge mole fraction at 700 and 800$^{\circ}C$, while it was decreased at both 900 and $1,000^{\circ}C$ as the Ge mole fraction was increased. The dry of idation rates were reduced for heavy Ge concentration, and large oxiidation time. In the parabolic growth region of $Si_{1-x}Ge_x$ oxidation, the parabolic rate constant are decreased due to the presence of Ge-rich layer. After the longer oxidation at the $1,000^{\circ}C$, AES showed that Ge peak distribution at the $Si_{1-x}Ge_x$ interface reduced by interdiffusion of silicon and germanium.

日,韓語における樣態修飾と狀態修飾 -形容詞連用形と韓國語形容詞-ge形を中心に-

김영숙 ( Young Suk Kim ) 한국일본어교육학회 2011 日本語敎育 Vol.55 No.-

本稿では、日韓語における形容詞連用形と形容詞-ge形の修飾機能上の異同を明らかにした上で、兩者の修飾機能上の違いが生じる理由について形容詞連用形と形容詞-ge形の成立條件の觀点から分析を試みた。日韓語における形容詞の修飾機能は(1)と(2)のような對立を示す。日本語の形容詞連用形は(1a)のような樣態修飾と(lb)のような結果狀態の修飾(RSP)はできるが、(1c)のようなイベント參與者の狀態修飾(DSP)はできない。それに對して、韓國語の形容詞-ge形は(1a)(1b)に對應する(2a)(2b)はもちろん、(1c)を直譯した(2c)も成立する。(1) a. 彼は激しく頭をたたいた。b. 太郞が壁を赤く塗った。c. 彼はカバンを重く持ち步く。(2) a. geu-neun simha-ge meoli-leul ttaely-eoss-da. (人名)は 激し-ge 頭を 叩(く)-Past-Decl b. cheolsu-ga byeog-eul bulg-ge chilha-ess-da. (人名)が 壁を 赤(い)-ge 塗(る)-Pres-Decl c. geu-neun gabang-eul mugeob-ge dul-go dani-n-da. (人名)は カバンを 重(い)-ge 持ち步(く)-Pres-Decl. このような日韓語の對立は、形容詞連用形と形容詞-ge形の成立條件の違いに起因するものと分析することができる。つまり、日本語でDSPが成立しないのは、動詞の意味的な性質によって認可される場合にのみ成立するという形容詞連用形の成立條件と、動詞の意味によって認可されないというDSPの性質が相容れないためであると說明することができる。一方、韓國語では、形容詞-ge形の成立に日本語のような制限はよく、DSPが成立すると考えられる。

Ab Initio Study of Mechanism of Forming Spiro-Ge-Heterocyclic Ring Compound From C₂Ge=Ge: and Formaldehyde

Lu, Xiuhui,Li, Yongqing,Ming, Jingjing Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.12

The $H_2Ge=Ge:$ and its derivatives ($X_2Ge=Ge:$, X = H, Me, F, Cl, Br, Ph, Ar${\ldots}{\ldots}$) is a new species. Its cycloaddition reactions is a new area for the study of germylene chemistry. The mechanism of the cycloaddition reaction between singlet state Cl2Ge=Ge: and formaldehyde has been investigated with CCSD(T)//MP2/$6-31G^*$ method. From the potential energy profile, it could be predicted that the reaction has only one dominant reaction pathway. The reaction rule presented is that the two reactants first form a fourmembered Ge-heterocyclic ring germylene through the [2+2] cycloaddition reaction. Because of the 4p unoccupied orbital of Ge: atom in the four-membered Ge-heterocyclic ring germylene and the ${\pi}$ orbital of formaldehyde forming a ${\pi}{\rightarrow}p$ donor-acceptor bond, the four-membered Ge-heterocyclic ring germylene further combines with formaldehyde to form an intermediate. Because the Ge: atom in intermediate hybridizes to an $sp^3$ hybrid orbital after transition state, then, intermediate isomerizes to a spiro-Ge-heterocyclic ring compound via a transition state. The research result indicates the laws of cycloaddition reaction between $H_2Ge=Ge:$ and formaldehyde, and laid the theory foundation of the cycloaddition reaction between $H_2Ge=Ge:$ and its derivatives ($X_2Ge=Ge:$, X = H, Me, F, Cl, Br, Ph, Ar${\ldots}{\ldots}$) and asymmetric ${\pi}$-bonded compounds, which is significant for the synthesis of small-ring and spiro-Ge-heterocyclic compounds. The study extends research area and enriches the research content of germylene chemistry.

Effect of Ge-Nanodot Incorporation on Light-Emission from ZnO Thin Films

최석호,이도규,김성,김창오,엄성환,오형택 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

ZnO films have been implanted with Ge- ions to doses (nGe) of (1.5 ∽ 4) ×1016 cm-2 and subsequently annealed at 700 ∽ 1000 ℃ for 20 min to form Ge nanodots (NDs) within the ZnO matrix. Transmission electron microscopy images demonstrate the existence of irregularly-shaped Ge NDs of ∽15 to ∽30 nm in the central region of the Ge--implanted ZnO films (ZnO:Ge) after annealing. The photoluminescence (PL) spectra of the annealed ZnO:Ge films are observed in the infrared (IR) range of ∽0.75 to ∽0.95 eV and show a maximum intensity at nGe = 1.5 ×1016 cm-2, which is consistent with the dose-dependent relative intensity ratio of UV and visible PL emissions from near-band-edge and oxygen-related deep levels (DLs), respectively. These PL behaviors are attributed to the Ge suboxide states at the interfaces of Ge NDs/DL sites and Ge-related molecular complexes within the ZnO matrix, as confirmed by the X-ray diraction patterns. ZnO films have been implanted with Ge- ions to doses (nGe) of (1.5 ∽ 4) ×1016 cm-2 and subsequently annealed at 700 ∽ 1000 ℃ for 20 min to form Ge nanodots (NDs) within the ZnO matrix. Transmission electron microscopy images demonstrate the existence of irregularly-shaped Ge NDs of ∽15 to ∽30 nm in the central region of the Ge--implanted ZnO films (ZnO:Ge) after annealing. The photoluminescence (PL) spectra of the annealed ZnO:Ge films are observed in the infrared (IR) range of ∽0.75 to ∽0.95 eV and show a maximum intensity at nGe = 1.5 ×1016 cm-2, which is consistent with the dose-dependent relative intensity ratio of UV and visible PL emissions from near-band-edge and oxygen-related deep levels (DLs), respectively. These PL behaviors are attributed to the Ge suboxide states at the interfaces of Ge NDs/DL sites and Ge-related molecular complexes within the ZnO matrix, as confirmed by the X-ray diraction patterns.

Optical Properties of Ge-Doped ZnO Thin Films Studied with Spectroscopic Elipsometry

Seoung Ho Baek,Do Kyu Lee,강태동,Suk-Ho Choi,이호선,Seung Hwan Eom 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1

We prepared Ge-doped ZnO (ZnO : Ge) thin films on silicon substrates by using RF magnetron sputtering. We used as targets mixtures of ZnO and Ge, the RF power was 70 and 150 W and the Ge mole ratio was varied between 0 mol% and 3 mol% with respect to the ZnO content. During growth, we used two kinds of gas ows: Ar : O₂ = 40 : 5 and Ar : N2 = 40 : 5. The substrate temperatures were kept at room temperature (RT) and 400 ℃. We measured the pseudo-dielectric functions by using spectroscopic ellipsometry at RT. By using the parametric optical constant model and performing alayer model analysis, we obtained the Kramers-Kronig-consistentdielectric functions of the ZnO : Ge films. To find the band gap energies of the ZnO : Ge films, we applied the standard critical point model to the 2nd derivatives of the dielectric functions (ε = ε₁ +ⅰε₂) of the ZnO : Ge films. Among the ZnO : Ge films grown on Si substrates, the thin films grown in the Ar and O₂ mixture showed dielectric functions closer to that of a purely crystalline ZnO film,which indicate shigh crystallinity. Theband-gapenergies of the ZnO:Ge film sincreased with increasing Ge content. We attribute the blue shift of the band-gap energy to the Burstein-Moss shift (band-filling effect) and/or to the alloying effect of ZnO : Ge. The larger blue shift of the ZnO : Ge films grown in the Ar and N₂ mixture suggests that more carriers were activated in that mixture than in the Ar and O₂ mixture. With increasing Ge content, the linewidth broadened due to an increase in alloy disorder. In the case of ZnO : Ge grown under a gas flow ratio of Ar : N₂ = 40 : 5, a deep-level transition was observed near 2.5 eV in the dielectric function spectra and is attributed to atransition related to oxygen vacancies. In order to investigate the effect of annealing on the ZnO : Ge films, we annealed the ZnO : Ge films grown on silicon substrates at RT with a gas how ratio of Ar : O₂ = 40 : 5 in oxygen (O2) ambient. When the annealing temperature was increased, both the band gap energy and broadening parameter of the ZnO : Ge film decreased.

Wafer level package of Au-Ge system using a Ge chemical vapor deposition (CVD) thin film

Choi, Kyeong-Keun,Hosseini, Nazanin,Kee, Jong,Kim, Sung-Kyu,Park, Chan-Gyung Elsevier 2016 APPLIED SURFACE SCIENCE - Vol.385 No.-

<P><B>Abstract</B></P> <P>A Ge thin film deposited by chemical vapor deposition (CVD) was used to obtain a uniform bonding between Au and Ge films for applications of wafer level packages (WLPs). This Ge CVD thin film showed selective growth on Au and Cu metals when the substrate has both metal and oxide. A one-step and two-step Ge deposition followed by eutectic bonding method was employed to bond the wafers. The samples were characterized by X-ray diffraction, field emission scanning electron microscopy equipped with an energy dispersive spectroscopy (FESEM-EDS), atomic force microscopy, high resolution Field emission transmission electron microscopy, IR inspection tool and secondary ion mass spectroscopy (SIMS). According to the IR inspection results, the two-step Ge deposited sample showed more uniform film compared to one-step deposition after eutectic bonding. Moreover, an improved bonding quality was obtained from the two-step process. Based on FESEM observations, a uniform and crater-free interface was detected between the bonded 4-inch wafers, in which the presence of Ge beside Au and Si was confirmed by EDS. SIMS profiles proved the formation of a thin Au-Ge interlayer at the bonded interface, which enhanced the bonding conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A ∼100nm CVD Ge film was deposited on Si wafer by two-step chemical vapor deposition. </LI> <LI> A wafer level eutectic bonding was used to bond the CVD Ge/Si and Au/Ti/Si wafers. </LI> <LI> The two-step Ge deposited sample showed uniform film after the eutectic bonding. </LI> <LI> A uniform interface was detected between the bonded wafers using two-step deposition. </LI> <LI> An Au-Ge interlayer formed at the bonded interface, which enhanced bonding quality. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

AFM을 이용한 Si (001) 표면에 Ge 나노점의 형성과 성장과정에 관한 연구

박정식,이상현,최명섭,송덕수,이성수,곽동욱,김도형,양우철,Park, J.S.,Lee, S.H.,Choia, M.S.,Song, D.S.,Leec, S.S.,Kwak, D.W.,Kim, D.H.,Yang, W.C. 한국진공학회 2008 Applied Science and Convergence Technology Vol.17 No.3

본 연구는 화학기상증착(Chemical Vapor Deposition)법을 이용하여 Si(100) 표면위에 Ge 나노점을 성장하여 나노점의 형성과 성장과정을 원자간력현미경(AFM)으로 조사하였다. 성장온도, Ge 증착량, 열처리시간의 변화에 따른 형성된 나노점의 모양, 크기, 표면 밀도의 변화를 분석하였다. $600^{\circ}C$의 성장온도에서 ${\sim}0.1ML/sec$의 증착율로 Ge을 증착한 결과, ${\sim}4ML$까지는 pseudomorphic한 Ge wetting 층이 형성되었으며, 증착시간을 증가하여 5ML 이상에서 Ge 나노점이 형성되기 시작하였다. Ge 증착량을 증가시킴에 따라 초기 나노점은 긴 지붕모양(elongated hut)구조로 형성되었고, 점차 크기가 증가함에 따라, 피라미드(pyramid), 돔(dome), 더 큰 Superdome 구조로 변형되었다. 초기 피라미드 형태의 나노점 평균크기는 ${\sim}20nm$이였으며, 가장 큰 superdome의 평균크기는 ${\sim}310nm$ 이상이었으며, 크기가 증가함에 따라 표면 밀도는 $4{\times}10^{10}cm^{-2}$에서 $5{\times}10^8cm^{-2}$로 감소하였다. 상대적으로 고온인 $650^{\circ}C$에서 Ge을 증착했을 경우, 피라미드 구조는 발견되지 않았으며, 대부분의 나노점은 돔 형태로 형성되었으며, 점차 superdome 형태로 변형되었다. 또한, 고온 성장된 시료의 열처리 시간을 증가함에 따라, 나노점의 크기는 점차 성장하였으나, 밀도는 거의 변화가 없었다. 이와 같은 나노점의 형태, 크기, 밀도의 변화는 나노점이 갖는 에너지의 최소화와 표면에서 원자들의 이동(diffusion)으로 설명할 수 있었다. 특히, AFM 이미지의 표면에 분포한 나노점들의 상대적인 위치를 분석한 결과, 유사한 크기의 근접한 나노점들은 점차 크기가 증가함에 따라 합쳐지는 Coalescence과정에 의해 성장하고, 크기가 다른 근접한 나노점들 사이에는 화학적 포텐셜에너지 차에 의한 ripening 과정의 성장을 관찰하였다. 즉, 형성된 나노점들은 국부적인 표면분포에 따라 나노점들은 두 성장과정이 동시 작용하여 성장함을 확인하였다. The nucleation and evolution process of Ge nano-islands on Si(001) surfaces grown by chemical vapor deposition have been explored using atomic force microscopy (AFM). The Ge nano-islands are grown by exposing the substrates to a mixture of gasses GeH4 and H2 at pressure of 0.1-0.5Torr and temperatures of $600-650^{\circ}C$. The effect of growth conditions such as temperature, Ge thickness, annealing time on the shape, size, number density, and surface distribution was investigated. For Ge deposition greater than ${\sim}5$ monolayer (ML) with a growth rate of ${\sim}0.1ML/sec$ at $600^{\circ}C$, we observed island nucleation on the surface indicating the transition from strained layer to island structure. Further deposition of Ge led to shape transition from initial pyramid and hut to dome and superdome structure. The lateral average size of the islands increased from ${\sim}20nm$ to ${\sim}310nm$ while the number density decreased from $4{\times}10^{18}$ to $5{\times}10^8cm^{-2}$ during the shape transition process. In contrast, for the samples grown at a relatively higher temperature of $650^{\circ}C$ the morphology of the islands showed that the dome shape is dominant over the pyramid shape. The further deposition of Ge led to transition from the dome to the superdome shape. The evolution of shape, size, and surface distribution is related to energy minimization of the islands and surface diffusion of Ge adatoms. In particular, we found that the initially nucleated islands did not grow through long-range interaction between whole islands on the surface but via local interaction between the neighbor islands by investigation of the inter-islands distance.

In-situ ellipsometry를 사용한 광기록매체용 Ge-Sb-Te 다층박막성장의 실시간 제어

김종혁,이학철,김상준,김상열,안성혁,원영희 한국광학회 2002 한국광학회지 Vol.13 No.3

광기록매체용 Ge-Sb-Te다층박막 성장과정을 in-situ 타원계를 사용하여 실시간으로 모니터하여 각 층의 두께를 제어하고 성장된 Ge-Sb-Te 다층박막을 ex-site 분광타원법으로 확인하였다. 보호층인 ZnS-SiO$_2$와 기록층인 Ge$_2$Sb$_2$Te$_{5}$을 단결정실리콘 기층 위에 스퍼터링 방법으로 각각 성장시키면서 구한 타원상수 성장곡선을 분석하여 성장에 따르는 보호층의 균일성 및 기록 층의 밀도변화를 파악하고 이를 기초로 하여 Ge-Sb-Te광기록 다층박막의 두께를 정밀하게 제어하였다. Ge$_2$Sb$_2$Te$_{5}$ 단층박막 시료의 복소굴절율은 eX-Situ 분광타원분석을 통하여 구하였다. 제작된 다층구조는 설정된 다층구조인 ZnS-SiO$_2$(1400$\AA$)$\mid$ GST(200 $\AA$)$\mid$ZnS-SiO$_2$(200$\AA$)와 각 층의 두께 및 전체 두께에서 1.5% 이내에서 일치하는 정확도를 보여주었다.주었다. Using an in-situ ellipsometer, we monitored the growth curve of optical recording media in real time. For confirmation of the thickness control using in-situ ellipsometry, we analyzed the deposited multi-layer sample made of Ge-Sb-Te alloy film and ZnS-Si0$_2$ dielectric films using an exsitu spectroscopic ellipsometer. The target material in the first sputtering gun is ZnS-SiO$_2$ as the protecting dielectric layer and that in the second gun is Ge$_2$sb$_2$Te$_{5}$ as the receding layer. While depositing ZnS-SiO$_2$, Ge$_2$Sb$_2$Te$_{5}$ and ZnS-SiO$_2$ films on c-Si substrate in sequence, we measured Ψ $\Delta$ in real time. Utilizing the complex refractive indices of Ge$_2$Sb$_2$Te$_{5}$ and ZnS-SiO$_2$ obtained from the analysis of spectroscopic ellipsometry data, the evolution of ellipsometric constants Ψ, $\Delta$ with thickness is calculated. By comparing the calculated evolution curve of ellipsometric constants with the measured one, and by analyzing the effect of density variation of the Ge$_2$Sb$_2$Te$_{5}$ recording layer on ellipsometric constants with thickness, we precisely monitored the growth rate of the Ge-Sb-Te multilayer and controlled the growth process. The deviation of the real thicknesses of Ge-Sb-Te multilayer obtained under the strict monitoring is post confirmed to be less than 1.5% from the target structure of ZnS-SiO$_2$(1400 $\AA$)IGST(200 $\AA$)$\mid$ZnS-SiO$_2$(200$\AA$).(200$\AA$).