Dissociation of trimethylgallium on the ZrB2(0001) surface

Manandhar, Kedar; Trenary, Michael; Otani, Shigeki; Zapol, Peter

doi:10.1116/1.4826881

Cited by 6 publications

(7 citation statements)

References 53 publications

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“…To achieve this goal, better information on the dissociation temperature and decomposition mechanism of NH 3 and other precursor gases on ZrB 2 (0001) is needed. The present work on molecular adsorption of ammonia at low temperatures therefore complements our recent work on the thermal decomposition of TMG 35 and the higher temperature deposition of N from NH 3 decomposition on the ZrB 2 (0001) surface. 24…”

Section: ■ Introductionsupporting

confidence: 61%

“…It is noteworthy that in the NH 3 /Pt(111) system, the N 1s BE of multilayer ammonia was 0.6 eV higher than that of monolayer ammonia . Also in our recent XPS study of TMG on ZrB 2 , we observed that the C 1s BE of multilayer TMG was ∼0.3 eV higher than that of the surface layer . Therefore, the 401.9 eV peak in Figure a is assigned to multilayer ammonia.…”

Section: Discussionmentioning

confidence: 70%

“…40 Also in our recent XPS study of TMG on ZrB 2 , we observed that the C 1s BE of multilayer TMG was ∼0.3 eV higher than that of the surface layer. 35 Therefore, the 401.9 eV peak in Figure 1a is assigned to multilayer ammonia. The peak at 397.5 eV agrees well with the measured BEs of atomic nitrogen on semiconductor and metal surfaces.…”

Section: ■ Resultsmentioning

confidence: 97%

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Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB₂(0001) Surface

et al. 2014

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X-ray photoelectron spectroscopy (XPS) and reflection absorption infrared spectroscopy (RAIRS) have been used to study the structure of molecularly adsorbed ammonia on the ZrB 2 (0001) surface and its subsequent dissociation. Spectra were obtained as a function of ammonia exposure to the surface at 95 K and as a function of annealing temperature following exposures at 95 and 300 K. The infrared peak positions do not vary with exposure, from the lowest submonolayer coverages to thick multilayers and are at the same values as those of solid ammonia. This indicates that the NH 3 molecules have high enough mobility at 95 K to aggregate into hydrogenbonded clusters with the same structure as that of solid ammonia. The peak positions match those of solid ammonia much better than those calculated for an isolated ammonia molecule adsorbed on top of a Zr atom, which was found to be the most stable binding site. Although aggregation into clusters at low temperatures implies a weak interaction with the substrate, a minor dissociation channel may exist, even at 95 K, as indicated by XPS through the appearance of a small N 1s peak at 397.5 eV attributed to atomic nitrogen in addition to a N 1s peak at 401.9 eV due to molecularly adsorbed NH 3 . Ammonia completely dissociates to atomic nitrogen and hydrogen for adsorption temperatures of 300 K and above. The hydrogen product of dissociation desorbs between 535 and 555 K, as indicated by the disappearance of a Zr−H vibration at 999 cm −1 .

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Section: ■ Introductionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 70%

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Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB₂(0001) Surface

et al. 2014

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“…The peaks at ∼1118.0 eV and ∼1119.6 eV for the double bilayer are due to GaN and Ga 2 O 3 , respectively [42]. Manandhar et al investigated the dissociation of trimethylgallium on ZrBr 2 (0001) surface and reported a significant shift in Ga binding energy of 1119.0 eV toward lower value of 1118.2 eV as gallium becomes more metallic [43]. The integrated intensity ratios of [Ga-Ga]/Ga Total were found to be 0.35 and 0.24, respectively, for the single and double bilayers.…”

Section: Resultsmentioning

confidence: 99%

Interfacial and electrical properties of nanolaminated HfO₂/Al₂O₃ dielectrics on GaN with an AlN interlayer

Kim

Yun

Choi

et al. 2019

Semicond. Sci. Technol.

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In this work, we investigated the interfacial properties of AlN/GaN heterostructure with HfO 2 /Al 2 O 3 (single bilayer) and HfO 2 /Al 2 O 3 /HfO 2 /Al 2 O 3 (double bilayer) dielectrics prepared by atomic layer deposition (ALD). From capacitance-voltage measurements, significant frequency dispersion was observed for the single bilayer. The interface traps for the double bilayer showed the exponential dependence of trap time constant to the applied voltage, indicating the high quality and uniform interface, whereas the single bilayer deviated from this dependence, revealing the non-uniformity of oxide charges. According to current-voltage measurements, the double bilayer showed much lower leakage current than the single bilayer. X-ray photoelectron spectroscopy measurements showed that Hf-Al-O bonding formed wider region for the double bilayer. For the single bilayer, the outdiffusion of Ga atoms into the AlN layer and the formation of Al-OH were observed more significantly. This work indicates that the double bilayer is a promising dielectric on the AlN/GaN heterostructure.

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“…Although we used the same XPS spectrometer for earlier studies of a ZrB 2 (0001) single crystal using a pass energy of 50 eV, 37,46 the sensitivity and resolution of the spectrometer has degraded with time.…”

Section: Introductionmentioning

confidence: 99%

Identification of a Stable B₂H₂ Intermediate in the Decomposition of Zr(BH₄)₄ on the Pd(111) Surface

Ranjan,

Redington,

Ologun

et al. 2024

J. Phys. Chem. C

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Tetrakis(tetrahydroborato)zirconium(IV), Zr(BH 4 ) 4 , is a volatile compound that has been widely used as a singlesource precursor to grow carbon-free thin films of zirconium diboride by chemical vapor deposition (CVD) on a wide range of substrates that include oxides, semiconductors, and metals. However, the basic surface chemistry of the compound that underlies the initial stages of the CVD process is largely unknown for any substrate. We studied the adsorption and decomposition of Zr(BH 4 ) 4 on a Pd(111) surface with the experimental techniques of reflection absorption infrared spectroscopy (RAIRS), temperatureprogrammed reaction spectroscopy (TPRS), and X-ray photoelectron spectroscopy (XPS) and with density functional theory and first-principles molecular dynamics simulations. After exposing Pd(111) at 90 K to Zr(BH 4 ) 4 (g), a RAIR spectrum was obtained that closely matched that of the pure compound, indicating that it adsorbs without dissociation at 90 K. However, upon heating to 200 K the RAIR spectrum undergoes dramatic changes indicating that a new surface species is formed that retains both terminal B− H bonds and bridging metal−H−B bonds, as indicated by B−H stretches in the ranges of 2563−2540 and 2143−2135 cm −1 , respectively. Hydrogen desorption is first observed at around 178 K and the presence of a stable hydrogen-containing surface intermediate is revealed by additional H 2 desorption peaks at 330 and 426 K. A combination of theoretical methods reveals that BH adsorbed at a 3-fold hollow site on the Pd(111) surface is the most stable species, but once formed two BH molecules can dimerize to form HBBH. A stable configuration for B 2 H 2 is achieved through formation of B−H---Zr bridge bonds with a Zr atom located at one or both ends of a B 2 H 2 molecule. Calculated vibrational frequencies and intensities provide an excellent match with the experimental RAIR spectra.

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Dissociation of trimethylgallium on the ZrB2(0001) surface

Cited by 6 publications

References 53 publications

Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB₂(0001) Surface

Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB₂(0001) Surface

Interfacial and electrical properties of nanolaminated HfO₂/Al₂O₃ dielectrics on GaN with an AlN interlayer

Identification of a Stable B₂H₂ Intermediate in the Decomposition of Zr(BH₄)₄ on the Pd(111) Surface

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Dissociation of trimethylgallium on the ZrB2(0001) surface

Cited by 6 publications

References 53 publications

Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB2(0001) Surface

Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB2(0001) Surface

Interfacial and electrical properties of nanolaminated HfO2/Al2O3 dielectrics on GaN with an AlN interlayer

Identification of a Stable B2H2 Intermediate in the Decomposition of Zr(BH4)4 on the Pd(111) Surface

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Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB₂(0001) Surface

Structure and Reactivity of Molecularly Adsorbed Ammonia on the ZrB₂(0001) Surface

Interfacial and electrical properties of nanolaminated HfO₂/Al₂O₃ dielectrics on GaN with an AlN interlayer

Identification of a Stable B₂H₂ Intermediate in the Decomposition of Zr(BH₄)₄ on the Pd(111) Surface