The 308 nm laser photodissociation of HN3 adsorbed on Si(111)-7 × 7

Bu, Y.; Lin, Ming‐Chang

doi:10.1016/0039-6028(94)91293-9

Cited by 14 publications

(15 citation statements)

References 41 publications

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“…The 120 K HREELS spectra taken from CH 3 CHO, CH 3 CDO and CD 3 CDO on Si(111)7×7 are shown in Figure . The expected peak shifts upon deuteration were observed, and the assignments of the vibrational modes are listed in Table together with the IR/Raman results for gaseous/liquid acetaldehyde. − In comparison with the 120 K CH 3 CHO HREELS spectrum, the two CH bending modes for CH 3 CDO shifted from 98 and 185 meV to 88 and ∼140 meV, respectively. The latter peak overlapped with the CC stretching and CH 3 symmetric deformation modes to give a broad peak centered at ∼138 meV.…”

Section: Resultsmentioning

confidence: 92%

“…The experiment was carried out in an ultrahigh-vacuum (UHV) system (Leybold, Inc.) with a base pressure of 5 × 10 -11 Torr. The system is equipped with HREELS, XPS, UPS, Auger electron spectrometer (AES), TPD, and low-energy electron diffractometer (LEED) as described elsewhere. − In the HREELS measurement, a 5 eV electron beam was used, and its full width at half-maximum (fwhm) was 7 meV in the straight-through mode. However, after scattering from a clean Si(111)7×7 surface at 120 K, the fwhm of the beam broadened to 12 meV.…”

Section: Methodsmentioning

confidence: 99%

“…Previously, we have investigated the surface chemistry of C-, N-, or O-containing small molecules, such as CH 2 CO (CD 2 CO), CO, HCN (DCN), NH 2 CHO, HN 3 (DN 3 ), and N 2 H 4 , on Si single-crystal surfaces. These studies helped us to better understand the behavior of CH x , NH x , and OH x species on Si substrates as well as the mechanisms for formation the of Si carbide, Si nitride, and Si oxide.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption and Thermal Decomposition of Acetaldehyde on Si(111)-7×7

Breslin

Lin

1997

J. Phys. Chem. B

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The thermal stability of acetaldehyde on Si(111)7×7 was studied with HREELS, XPS, UPS, and TPD techniques. Acetaldehyde molecules were found to adsorb molecularly on the surface at 120 K, yielding HREELS peaks at 98, 124, 144, 185, and 380 and UPS peaks at 5.7, 7.6, 10.0, and 13.9 eV below E f . Analysis of the XPS O 1s (shoulder at 531; 532 eV) and C 1s (288 and 285 eV) spectra indicated that the acetaldehyde was partially dissociated at 120 K. At ∼350 K, the initial HREELS peaks at 185 and 144 meV diminished while peaks at 100 and 208 meV emerged, which indicated the desorption and/or dissociation of the C-C bond and the formation of Si-O and Si-CH 3 species. The UPS peaks at 5.7 and 10.0 eV diminished, and a new peak at 6.5 eV dominated the spectra from 350 to 1150 K. The parent mass was found by TPD to desorb at 320 K. At 500 K, the 100 meV HREELS peak vanished and a new peak at 270 meV became noticeable, indicating the breaking of the C-H bond and the formation of Si-H (D) species. TPD results indicated that H (D) species desorbed at around 800 K. By 1150 K, peaks at ∼110 meV (HREELS) and ∼7 eV (UPS) were the only significant features not found in the clean Si(111) spectra. In the XPS spectra, initial multiple features had converged by 350 K, and with increased temperature both the resulting O 1s and C 1s peaks shifted toward lower binding energy. By 1150 K, the O 1s peak had disappeared, leaving silicon carbide on the substrate.

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Section: Resultsmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adsorption and Thermal Decomposition of Acetaldehyde on Si(111)-7×7

Breslin

Lin

1997

J. Phys. Chem. B

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“…Unfortunately, nitridation of Al using ammonia is difficult due to the high N−H bond dissociation energy, which requires that AlN growth by metalorganic chemical vapor deposition (MOCVD) be performed at ∼1273 K. This has led to a search for alternate low-temperature methods and an interest in the surface chemistry of nitridation precursors. Successful methods for nitridation of Al metal have employed N-ion implantation, , N 2 H 4 adsorption, , or N 2 glow discharge. , We recently demonstrated that hydrazoic acid, HN 3 , is an effective precursor for low-temperature growth of ordered AlN(0001) thin films on Al(111), and the chemistry of HN 3 on Si, − Ge, GaAs, and diamond surfaces has also been reported. Several groups have used HN 3 as a replacement for ammonia in MOCVD or gas-source molecular beam epitaxy of BN, GaN, − and InN but not, to our knowledge, of AlN.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Thermal Decomposition of Hydrazoic Acid on Al(111)

1996

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The surface chemistry of hydrazoic acid (HN3) on Al(111) was investigated from 100 to 800 K with temperature-programmed desorption, infrared reflection−absorption spectroscopy (IRRAS), Auger electron spectroscopy, and low-energy electron diffraction (LEED). IRRAS suggests that the first monolayer dissociatively chemisorbs as N2(ads) and NH(ads) at 120 K. Subsequently, HN3 adsorbs molecularly in two phases, a physisorbed second layer and a condensed multilayer. In the former, the N3 chain of the HN3 is aligned normal to the substrate surface, while in the latter HN3 exhibits a random orientation. Molecular HN3 desorbs at 125 K, and two decomposition products, N2 and H2, desorb at 295 and 615 K, respectively. Mixed-isotope desorption experiments show that N2 is derived from an intact NN species, rather than from recombinative desorption of N(ads), and is consistent with the IRRAS observation of chemisorbed N2. IRRAS indicates that the NH species dissociates into N(ads) and H(ads) above 320 K, with H2 thermal desorption resulting from dissociation of the AlH x (1 ≤ x ≤ 3) moiety. After the sample was annealed at 800 K, N was observed with Auger spectroscopy. The partially nitrided Al(111) surface exhibits a concentric, double hexagonal LEED pattern indicating AlN(0001) islands. IRRAS indicates that the islands are Al-terminated and capped with H at temperatures as high as 700 K.

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“…13 John and co-workers 14 have reported the photochemically enhanced CVD of GaN on sapphire when mixtures of Ga͑CH 3 ) 3 and NH 3 were irradiated with either an ArF laser ͑193 nm͒ or a low pressure Xe lamp, at a substrate temperature of 700 K. The mechanism is unknown in this case, but appears to involve fragmentation of both precursors by absorption at wavelengths below 250 nm. Both of these mechanisms appear to be quite different from that found in the present experiments.…”

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confidence: 93%

Mechanism of the photochemically induced reaction between Ga(CH3)3 and HN3 and the deposition of GaN films

Linnen

Coombe

1998

Applied Physics Letters

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Gaseous HN3 reacts with surface-bound Ga(CH3)x species slowly at 300 K to produce thin films containing azide-substituted gallium compounds. When mixtures of HN3 and Ga(CH3)3 over the surface are irradiated at 253.7 nm, the reaction is dramatically accelerated, and films containing GaN and complexed N2 are produced. Heating of these films to 400 K drives off the N2 leaving GaN. The mechanism of the reaction is thought to involve photodissociation of HN3 to produce excited NH(a1Δ) and N2, followed by insertion of the NH(a1Δ) into the Ga–C bond of surface-bound Ga(CH3)x molecules. The insertion product eliminates CH4 to leave GaN.

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The 308 nm laser photodissociation of HN3 adsorbed on Si(111)-7 × 7

Cited by 14 publications

References 41 publications

Adsorption and Thermal Decomposition of Acetaldehyde on Si(111)-7×7

Adsorption and Thermal Decomposition of Acetaldehyde on Si(111)-7×7

Adsorption and Thermal Decomposition of Hydrazoic Acid on Al(111)

Mechanism of the photochemically induced reaction between Ga(CH3)3 and HN3 and the deposition of GaN films

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