Organometallic chemical vapor deposition of copper oxide thin films

Chang, Yuneng

doi:10.31274/rtd-180813-13089

Cited by 2 publications

(3 citation statements)

References 14 publications

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“…Due to potential applications and local economic market aspect, CVD of copper and related bimetallic oxide compounds using metal acetylacetonates have been a research project for several years in this group since 1990s [1]. In a study to investigate the CVD of copper chromite (CuCr 2 O 4 ) spinel phase using copper acetylacetonate, Cu(C 5 H 7 O 2 ) 2 and chromium acetylacetonate, Cr(C 5 H 7 O 2 ) 3 .…”

Section: Introductionmentioning

confidence: 99%

A Study on unique Crystal Morphology observed in the Polycrystalline Copper CVD

Chang

Chen

2001

MRS Proc.

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Nanostructure copper whisker growth was observed in an atmospheric pressure chemical vapor deposition (CVD) system, which used copper acetylacetonate vapor and 10-15 torr of water vapor as reactants, with 0.04-0.10 torr of chromium acetylacetonate vapor added as growth promoting catalyst. Water vapor initiated nucleation of these helical, spiral shape Cu (111) and (200) polycrystalline whiskers. While chromium acetylacetonate accelerated the growth rate. Copper whiskers had radii from 0.1 to 0.24 µm, lengths from 1 to 10 µm, and distribution density of 0.20-3.6 whiskers/µm 2 . Dependence of such whisker characteristics on temperature, partial pressures of H 2 O and chromium acetylacetonate was used to construct a kinetic model. From the Arrhenius equation, data analysis for whisker growth rate against deposition temperature showed that the activation energy for whisker growth along radial direction is 12.4 kcal/mol, and 19.6 kcal/mol for growth along axial direction. Based on such data and SEM observations, a base vapor-liquid-solid (VLS) model involving BCF theory was proposed to describe the governing mechanism for the axial growth. This model interpreted the competitive growth phenomena in both radial and axial directions, and controlling steps for radial and axial growth being assigned to mass transfer and surface reaction, respectively. INTRODUCTIONDue to potential applications and local economic market aspect, CVD of copper and related bimetallic oxide compounds using metal acetylacetonates have been a research project for several years in this group since 1990s[1]. In a study to investigate the CVD of copper chromite (CuCr 2 O 4 ) spinel phase using copper acetylacetonate, Cu(C 5 H 7 O 2 ) 2 and chromium acetylacetonate, Cr(C 5 H 7 O 2 ) 3 . As oxygen was replaced with water vapor as co-reactant to explore the chemical system, it was discovered that the deposits being primarily fibrous like polycrystalline copper deposits, but not copper chromite [2]. The analysis results indicated that such fibrous deposits being polycrystalline copper "whisker". There are some differences between classical vapor grown whiskers and the materials found in the metal acetylacetonate/water vapor CVD system. As whiskers are usually single crystal, straight with sharp tips, whereas the fibrous copper deposits were polycrystalline, spiral or helical shape with round tips. Since the vapor grown whisker model is well established, we use this model to describe our observations.

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Section: Introductionmentioning

confidence: 99%

A Study on unique Crystal Morphology observed in the Polycrystalline Copper CVD

Chang

Chen

2001

MRS Proc.

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Section: Introductionmentioning

confidence: 99%

“…Cu dpoed single crystal ZnO was also grown by chemical vapor transport [5]. A thin film deposition process, which delivered aerosol droplets containing dihydrate zinc acetate and copper acetate precursor solution onto heated substrate, has been claimed to produce Cu doped ZnO films with resistivity increased by a factor of 1000 [6].Recently, MOCVD has been employed to prepare oxide ceramics due to advantages over traditional process: In MOCVD, surface adatoms migrate along depositing surface by surface diffusion, which has an activation energy barrier much lower than the energy for bulk diffusion, a essential step in solid sintering process. Thus, MOCVD has the ability to deposit thin film materials at lower temperatures and broaden the process window for crystalline ceramics.…”

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Zinc Oxide/Copper Oxide Mixed Films Deposited by CVD

Chang

Yeh

2001

MRS Proc.

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Metal organic chemical vapor deposition (MOCVD) was used to prepare ZnO/Cu 2 O mixed films. The process condition studied were: deposition temperature from 360 o C to 440 o C, partial pressures of oxygen, 190-380 torr, precursor copper acetylacetonate (Cu(acac) 2 ), 0.21 torr, and zinc acetylacetonate(Zn(acac) 2 ), 0.45 torr. AES and XPS analysis showed average elemental content being Cu, 52-66%, Zn, 11-20%, O, 30-40%. Copper presented primarily as Cu(I) ions, and Zn as Zn(II) ions. SEM, SAM and XRD indicated that deposited films were polycrystalline with composite structure. Some films had a continuous ZnO thin layer with flat surface, equiax fine grained. On the top of ZnO layer were covered by discrete, irregular shape, coarse Cu 2 O grains. Primary Cu 2 O phases were (110), (111), and (200) orientation. ZnO phases were (002), and (103). SEM showed the impact of deposition temperature on Cu 2 O grain size. Such data were used to estimate the activation energy for grain growth. In fact, to our experiences from these studies, binary metal oxide CVD showed a wide spectrum of film microstructure and morphology. These phenomena reflect the result caused by both thermodynamics as film composition, and kinetics as mass transfer/ surface reaction rate. INTRODUCTIONSimultaneously depositing Zinc oxide/copper oxide mixed films is an attractive research topic. Zinc oxide and copper oxide are the basic ingredients for methanol synthesis catalysts. Recent research showed the phase boundary between ZnO domain and Cu 2 O domain were of great importance to catalyst surface activities [1]. For piezoelectric micro acuator use, Cu doped ZnO films with higher resistivity, which allow lower operation frequency(<1 MHz) for ZnO MEMS devices such as microlevers, can reduce the device driving voltage and save energy [3]. Lamb has used ion implantation to prepare Cu doped(10 16~1 0 17 ions/cm 2 ) ZnO films and after annealing at 500 o C, achieved a reisitivity of 3X10 12 Ωcm [2]. On the other hand, cuprite, or cuprous oxide Cu 2 O, is a metal deficient, p type semiconductor materials, with its hole density and conductivity vary with system oxygen pressure, and temperature. With antifluorite cubic unit lattice, Cu 2 O exhibits Schottky-type disorder, and has been used for rectifying devices [3]. In the energy band diagram of Cu 2 O, there are one localized energy level associated with the cation vacancy center and two localized energy levels resulting from the anion vacancy centers. R.F. sputtering has been used to deposit (Zn, Cu)O films with ZnO pellet target bonded on a larger copper plate [4]. Cu dpoed single crystal ZnO was also grown by chemical vapor transport [5]. A thin film deposition process, which delivered aerosol droplets containing dihydrate zinc acetate and copper acetate precursor solution onto heated substrate, has been claimed to produce Cu doped ZnO films with resistivity increased by a factor of 1000 [6].Recently, MOCVD has been employed to prepare oxide ceramics due to advantages over traditional process: In MOCVD,...

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Organometallic chemical vapor deposition of copper oxide thin films

Cited by 2 publications

References 14 publications

A Study on unique Crystal Morphology observed in the Polycrystalline Copper CVD

A Study on unique Crystal Morphology observed in the Polycrystalline Copper CVD

Zinc Oxide/Copper Oxide Mixed Films Deposited by CVD

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