SiH Surface Species Research Articles

Etching and Chemical Control of the Silicon Nitride Surface.

Silicon nitride is used for many technological applications, but a quantitative knowledge of its surface chemistry is still lacking. Native oxynitride at the surface is generally removed using fluorinated etchants, but the chemical composition of surfaces still needs to be determined. In this work, the thinning (etching efficiency) of the layers after treatments in HF and NH4F solutions has been followed by using spectroscopic ellipsometry. A quantitative estimation of the chemical bonds found on the surface is obtained by a combination of infrared absorption spectroscopy in ATR mode, X-ray photoelectron spectroscopy, and colorimetry. Si-F bonds are the majority species present at the surface after silicon nitride etching; some Si-OH and a few Si-NHx bonds are also present. No Si-H bonds are present, an unfavorable feature for surface functionalization in view of the interest of such mildly reactive groups for achieving stable covalent grafting. Mechanisms are described to support the experimental results, and two methods are proposed for generating surface SiH species: enriching the material in silicon, or submitting the etched surface to a H2 plasma treatment.

Chemical reactions during plasma-enhanced atomic layer deposition of SiO2 films employing aminosilane and O2/Ar plasma at 50 °C

We report the temporal evolution of surface species observed in situ using attenuated total reflection Fourier transform infrared absorption spectroscopy (ATR-FTIR) during plasma-enhanced atomic layer deposition (PE-ALD) of SiO2 films employing aminosilane and an O2/Ar plasma at a temperature of 50 °C. Reversals in the appearance of IR absorbance features associated with SiO–H, C–Hx, and Si–H proved to coincide with the self-limiting reaction property in ALD. Our IR results indicate that an O2/Ar plasma can both removed CHx groups and transform SiH surface species to SiOH. In addition, SiO2 deposition was confirmed by a continuous increase in Si–O absorbance with each PE-ALD step, which becomes stable after several cycles. On the basis of our results, the mechanism of low temperature SiO2 PE-ALD was discussed.

Gel-pad microarrays templated by patterned porous silicon for dual-mode detection of proteins

A proof-of-concept study demonstrated the feasibility of a novel gel-pad microarray on porous silicon chips, by initiation of an atom transfer radical propagation (ATRP) polymerisation of (polyethylene glycol) methacrylate (PEGMA) with surface Si-H species, stepwise chemical conversions of the gel membrane to an NTA-Ni2+/histidine-tagged protein system, and matrix-assisted laser desorption/ionisation mass spectroscopy (MALDI MS) and fluorescence detections.

Unusual hydrogen distribution and its change in hydrogenated amorphous silicon prepared using bias electric-field molecular beam deposition

Hydrogenated amorphous silicon (a-Si:H) films prepared using a molecular beam deposition (MBD) method show an unusually sharp, narrow infrared absorption peak at 2080–2090cm−1, which is thought to result from surface SiH species in the a-Si:H. The sharp, narrow peak is eliminated by a bias electric field of several kilovolts during deposition. The absence or presence of incoming high-energy silicon atoms or clusters accelerated by the field seems to be crucial for the resulting network structure and hydrogen distribution in a-Si:H prepared using MBD.

Etching Behavior of Silicon Nanowires with HF and NH4F and Surface Characterization by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy: Similarities and Differences between One-Dimensional and Two-Dimensional Silicon Surfaces

A systematic study of the etching behavior of one-dimensional (1-D) Si nanowires (SiNWs) in various HF and NH4F etching solutions is reported. The concentration and pH dependences of the etching time (which is inverse to the "stability") of the SiNWs in these solutions were investigated. A V-shaped bimodal etching curve was observed for HF solutions with concentrations of 0.5-40%. Specifically, SiNWs exhibit high stability in both low (0.5%) and high (40%) concentrations of HF solution, with the lowest stability (i.e., fastest etching rate) occurring at 2% (1 M) HF solution. With NH4F, the time needed to totally etch away the SiNWs sample decreases with increasing concentration (from 1-40%). The opposite is true when the pH of the NH4F solution was maintained at 14. These surprising results were rationalized in terms of "passivation" of the SiNW surfaces by HF or related molecules via hydrogen bonding for Si-H-terminated surfaces in HF solutions (with low pH values) and by NH4(+) ions via ionic bonding for Si-O(-)-terminated surfaces in NH4F solutions (with high pH values), respectively. Furthermore, it was found that SiNWs are stable only in relatively narrow pH ranges in these solutions. When SiNWs are etched with HF, the stability range is pH = 1-2 where the surface moieties are Si-H(x) species (x = 1-3). When SiNWs are etched with NH4F, the stability range is pH = 12-14 where the surface moieties are mainly Si-(O-)x species (x = 1-3). These rationales were confirmed by attenuated total reflection Fourier transform infrared spectroscopy measurements, which showed that, while etching SiNWs with HF gave rise to Si-H(x) surface species, no Si-H(x) species were observed when SiNWs were etched with NH4F. The latter finding is at odds with the corresponding results reported for the two-dimensional (2-D) Si wafers where etching with either HF or NH4F produces Si-H(x) species on the surface. This difference suggests either that the etching mechanisms for NH4F versus HF are different for SiNWs or, more likely, that the Si-H(x) surface species produced in NH4F solutions are so unstable that they are hydrolyzed readily at pH > 4. The similarities and differences of the etching behaviors and the resulting surface speciations between the 1-D SiNWs and the 2-D Si wafers suggest that the nanoscale structures as well as the low dimensionality of SiNWs may have contributed to the rapid hydrolysis of the surface Si-H(x) species in NH4F solutions, especially at high pH values.

An FTIR study of porous silicon layers exposed to humid air with and without pyridine vapors at room temperature

Oxidation processes can strongly influence the properties of porous silicon (PS) material. In this paper, we present the results of FTIR studies for the oxidation process of PS exposed to humid air alone or together with saturated pyridine vapor at room temperature in the time range from 0.1 to 10,000 min. The oxidation has been followed by recording the time evolution of the IR absorption intensities of the main species involved in the process, namely: Si–H x , O y Si–H x , Si–OH and Si–O–Si. We found that in the presence of pyridine the oxidation is much faster. We show that the asymptotic value of silicon oxide amount is the same in both cases (with or without pyridine) and is strictly related to the original content of SiH surface species present in the sample. The role of the pyridine in the oxidation process is discussed.

SiH surface species on a SiC nanosized powder: ab initio and FT-IR studies of their behaviour under oxidation

Oxidation of silicon carbide is unavoidable due to contamination by the surrouding atmosphere. The silicon carbide surface presents SiH groups whose stretching frequency is precisely very sensitive to the silicon environment. Fourier transform infrared spectrometry combined with a specific cell makes it possible to analyze these SiH surface species in situ on a SiC nanosized powder, and to follow the shifts of the ν(SiH) frequency under controlled oxidation treatments. A decomposition of the ν(SiH) absorption band into its components shows the evolution of the frequencies as a function of the degree of oxidation. Simple ab initio models are then proposed to represent the SiH surface species according to the degree of oxidation. The validity of these models is checked by comparing the evolution of the ν(SiH) calculated frequencies with the values obtained from the decomposition analysis. It is demonstrated that the ab initio models cannot fit the experimental data as long as the oxidation mechanism is considered only as a direct carbon-oxygen substitution in the silicon environment. To obtain a satisfactory fit the oxygen diffusion inside the bulk must also be taken into account, which is in agreement with the experimental result proving that the SiC grains are not entirely covered by a silica layer.

Atomic-hydrogen-induced restructuring of the Si(100)(2 × 1)-K surface

The interaction of hydrogen atoms with the Si(100)(2 × 1)-K surface has been studied by using thermal desorption and electron energy loss spectroscopy. We have found that hydrogen adsorption induces the formation of potassium hydride islands at 90 K for even one-monolayer coverage of K, indicative of restructuring of the K-covered surface induced by hydrogen adsorption. The proposed reaction mechanism is as follows: incoming H atoms react with surface SiK species to generate surface SiH species and K atoms with the K atoms subsequently reacting with incoming H atoms to form potassium hydride. We discuss the relevance of the present results to the reaction of the metal-modified Si surface with hydrogen atoms.

Hydrogen desorption from Si(100)(2 × 1)-H induced by potassium adsorption

The interaction of K with Si(100)(2 × 1)-H has been studied by using thermal desorption and electron energy loss spectroscopy. We have found that above 360 K potassium adsorption induces concomitant H 2 desorption. This mechanism has been ascribed to a two step process consisting of the reaction of an incoming K atom with surface SiH species to form a surface complex, followed by the decomposition of this complex to give rise to the H 2 desorption. We have found that the isolated reaction intermediate, whose decomposition leads to the H 2 desorption around 450 K, is formed by the deposition of a small amount of K at 90 K. For the deposition of a large amount of K, the reaction intermediates form two types of potassium hydrides upon annealing and give rise to sharp H 2 desorption peaks at 360 and 380 K. Analysis of the K uptake curves above 360 K in terms of the Kisliuk model shows that K adsorption occurs via a precursor-mediated process, which is similar to that on clean Si(100)(2 × 1) but with a much low probability ( < 1 10 ) for the precursor to chemisorb. We suggest that the low probability for chemisorption is due to the activation barrier, estimated to be ∼ 3 kcal/mol, for the precursor K atoms to react with surface SiH species.

Adsorption and decomposition of trichlorosilane and trichlorogermane on porous silicon and Si(100)2×1 surfaces

The adsorption and decomposition of trichlorosilane (SiHCl3) and trichlorogermane (GeHCl3) on silicon surfaces were studied using Fourier transform infrared (FTIR) spectroscopy and temperature programmed desorption investigations. The FTIR transmission spectroscopy experiments were performed in situ in an ultrahigh vacuum chamber on high surface area porous silicon samples. The FTIR spectra revealed that SiHCl3 dissociatively adsorbed at 200 K and formed SiH, SiClx, ClSiH, and Cl2SiH surface species. The presence of ClxSiH species indicated incomplete decomposition of SiHCl3 upon adsorption at 200 K. GeHCl3 also dissociatively adsorbed at 200 K and formed SiH and SiClx species. The absence of an infrared absorption in the Ge–H stretching region suggests complete transfer of hydrogen from Ge to surface Si atoms at 200 K. The thermal stabilities of the surface species were then studied with annealing experiments. The ClxSiH species deposited by SiHCl3 exposure at 200 K decomposed between 200 and 590 K and formed additional SiH and SiCl species. The SiClx (x=2 or 3) species deposited by either GeHCl3 or SiHCl3 dissociative adsorption converted to silicon monochloride species between 200 and 600 K. The SiH surface species subsequently decreased at temperatures between 680 and 780 K as H2 desorbed from the silicon surface. FTIR spectroscopy was also utilized to monitor the adsorption of SiHCl3 and GeHCl3 on porous silicon at different surface temperatures. These adsorption studies were in agreement with the thermal annealing experiments. Temperature programmed desorption (TPD) studies were performed following saturation SiHCl3 and GeHCl3 exposures on Si(100)2×1. After SiHCl3 adsorption, the only desorption species were H2, HCl, and SiCl2, and they were observed at 810, 850, and 970 K, respectively. Following GeHCl3 adsorption, the TPD experiments monitored H2, HCl, SiCl2, and Ge at 810, 850, 950, and 1200 K, respectively. The adsorption kinetics of SiHCl3 and GeHCl3 were also measured on Si(100)2×1 and initial reactive sticking coefficients of S0≊.019 for SiHCl3 and S0≊1 for GeHCl3 were determined at 500 K. These experiments provide insight into the surface chemistry of chlorosilanes and chlorogermanes during Si, Ge, and Si1−xGex chemical vapor deposition on silicon surfaces.

Theoretical Modelling of the Surface Oxidation of a Silicon Carbide Nanopowder, Based on the v(SiH) Frequency Evolution

AbstractDue to hydrolysis by atmospheric water, the first atomic layer of silicon carbide contains oxygen atoms. The oxygen content on the surface dramatically increases for nanosized SiC powder and strongly affects the overall properties. The presence of SiH groups on the SiC surface, already proven by Fourier transform infrared spectrometry, can be used to investigate the oxidation mechanism. Indeed, the v(SiH) stretching frequency known to strongly depend on the surrounding electronegativity of the silicon atom is directly related to the oxidation degree. Based on our infrared spectroscopic experimental data, ab initio calculations were performed on models representing the SiH surface species in different environments. Using the Hartree-Fock method with 3–21G and 6–31G basis sets, the v(SiH) frequencies were calculated for each model versus the number of substituted oxygen atoms. The comparison with the experimental values led to a discussion of our proposed models and of the SiC surface oxidation mechanism.

FTIR Studies of CH3OH on Porous Silicon

ABSTRACTFourier transform infrared spectroscopy (FTIR) was used to investigate the reaction of methanol with porous silicon and hydrogen passivated porous silicon. At 300 K methanol adsorbs onto hydrogen free porous silicon by cleavage of the O-H bond. Both of the resulting surface species, Si-H and Si-OCH3, were determined to be stable up to ∼500 K. Above 500 K the Si-OCH3 moiety decomposes by breakage of the C-O and C-H bonds. The resulting carbon and oxygen were incorporated into the porous layer and additional Si-H surface species were detected. Further heating to 900 K removed the Si-H surface species. Adsorption of methanol onto hydrogen-passivated porous silicon did not occur until 600 K. At temperatures beyond 600 K, oxygen and carbon incorporation into the porous layer and Si-OCH3, Si-CH3, and Si-H surface species were seen. The previously unseen Si-CH3 surface species is believed to be stabilized by oxygen incorporation.

Decomposition of silicon hydrides following disilane adsorption on porous silicon surfaces

Disilane (Si 2H 6) is used for silicon chemical vapor deposition (CVD) and is a potential precursor for atomic layer epitaxy (ALE) on silicon surfaces. In this study, Fourier transform infrared (FTIR) transmission spectroscopy was employed to examine the adsorption and decomposition of disilane on high surface area porous silicon surfaces. The FTIR spectra revealed that disilane dissociatively adsorbs on porous silicon surfaces at 200 K to form a large fraction of SiH 3 surface species and some SiH 2 and SiH surface species. The SiH x stretching modes between 2125–2156 cm −1, the SiH 3 degenerate deformation mode at 862 cm −1 and the SiH 2 scissor mode at 907 cm −1 were then employed to monitor the decomposition of the surface hybride species during thermal annealing. Between 200–600 K, the SiH 3 species decreased and were depleted from the silicon surface. Concurrently, the SiH 2 surface species were observed to increase between 200–440 K and subsequently to decrease between 440–620 K. Only monohydride species remained on the porous silicon surface at 620 K. Above 640 K, the SiH surface species decreased concurrently with H 2 desorption. Adsorption studies were also conducted at various isothermal temperatures. These disilane adsorption and decomposition experiments provide important insights to the surface chemistry during silicon CVD and ALE processing.

Adsorption and decomposition of diethylgermane on porous silicon surfaces

Diethylgermane [(CH 3CH 2) 2GeH 2], (DEG), is a potential molecular precursor for germanium deposition on silicon surfaces. In this study, Fourier transform infrared (FTIR) transmission spectroscopy was employed to examine the adsorption and decomposition of DEG on high surface area porous silicon surfaces. The FTIR spectra revealed that DEG dissociatively adsorbs on porous silicon surfaces at 200 K to form SiH, GeH and SiCH 2CH 3 surface species. No spectral features were observed for GeCH 2CH 3 surface species. The C-H stretching modes between 2959 and 2882 cm −1, the Si-H stretch at 2082 cm −1 and the Ge-H stretch at 1999 cm −1 were then employed to monitor the decomposition of the surface species during thermal annealing. Between 300 and 640 K the GeH species transferred hydrogen to the silicon surface and formed SiH species. The SiCH 2CH 3 species decomposed to yield gas phase CH 2CH 2 and additional SiH surface species between 400 and 700 K. These reaction products were consistent with a β-hydride elimination mechanism, i.e. SiCH 2CH 3 → SiH + CH 2CH 2. From 660–800 K the SiH surface species decreased concurrently with H 2 desorption. The decomposition pathways of the surface species following DEG adsorption indicate that DEG may be useful for germanium deposition on silicon surfaces.

Adsorption and decomposition of diethylgermane on porous silicon surfaces

Diethylgermane [(CH 3CH 2) 2GeH 2], (DEG), is a potential molecular precursor for germanium deposition on silicon surfaces. In this study, Fourier transform infrared (FTIR) transmission spectroscopy was employed to examine the adsorption and decomposition of DEG on high surface area porous silicon surfaces. The FTIR spectra revealed that DEG dissociatively adsorbs on porous silicon surfaces at 200 K to form SiH, GeH and SiCH 2CH 3 surface species. No spectral features were observed for GeCH 2CH 3 surface species. The C-H stretching modes between 2959 and 2882 cm −1, the Si-H stretch at 2082 cm −1 and the Ge-H stretch at 1999 cm −1 were then employed to monitor the decomposition of the surface species during thermal annealing. Between 300 and 640 K the GeH species transferred hydrogen to the silicon surface and formed SiH species. The SiCH 2CH 3 species decomposed to yield gas phase CH 2=CH 2 and additional SiH surface species between 400 and 700 K. These reaction products were consistent with a β-hydride elimination mechanism, i.e. SiCH 2CH 3→SiH+CH 2=CH 2. From 660–800 K the SiH surface species decreased concurrently with H 2 desorption. The decomposition pathways of the surface species following DEG adsorption indicate that DEG may be useful for germanium deposition on silicon surfaces.

Comparison of Trichlorosilane and Trichlorogermane Decomposition on Silicon Surfaces Using FTIR Spectroscopy

ABSTRACTFourier transform infrared (FTIR) transmission spectroscopy was used to compare the decomposition of trichlorosilane (SiHCl3) and trichlorogermane (GeHCl3) on silicon surfaces. Chlorosilanes, such as SiHCl3 are employed in silicon chemical vapor deposition (CVD). Chlorosilanes and chlorogermanes are also possible molecular precursors for the controlled atomic layer growth of silicon and germanium. GeHCl3 may be useful for the deposition of germanium on silicon surfaces and the growth of Si1−xGex heterostructures. The FTIR studies were performed in-situ in an ultra-high vacuum chamber on high surface area, porous silicon samples. The FTIR spectra revealed that SiHCl3 dissociatively adsorbs at 200 K to form SiH, SiClx, ClSiH and Cl2SiH surface species. The presence of ClxSiH species is revealed by ClxSiH stretching (2196 cm−1) and bending (775, 744 cm−1) vibrations. The presence of these modes indicates that there is incomplete decomposition of SiHCl3 upon adsorption at 200 K. GeHCl3 also dissociatively adsorbs at 200 K to form SiH and SiClx species. An infrared absorption feature in the Ge-H stretching region (1970–1995 cm−1) was not detected in the FTIR spectrum. The absence of a Ge-H absorption feature argues that there is a complete transfer of hydrogen from germanium to surface silicon atoms at 200 K. The thermal stabilities of the surface species were studied with annealing experiments. The Clx SiH formed upon initial SiHCl3 exposures at 200 K were observed to decompose between 200–590 K and form additional surface SiH and SiCl species. For both GeHCl3 and SiHCl3 dissociative adsorption on porous silicon, the SiCL. (x = 2 or 3) surface species were converted to silicon monochloride surface species between 200–600 K. In addition, SiH surface species were lost upon annealing between 680–780 K as H2 desorbed from the surface. The adsorption kinetics of SiHCl3 and GeHCl3 were also monitored on porous silicon at various isothermal temperatures. These experiments provide insight into the surface chemistry of chlorosilanes and chlorogermanes during CVD and atomic layer controlled growth.

Germanium Deposition on Silicon: Surface Chemistry of (CH3CH2)2GeH2 and GeC14

ABSTRACTDiethylgermane, (CH3CH2)2GeH2, and germanium tetrachloride, GeCl4 may be useful precursors for chemical vapor deposition (CVD) or atomic layer controlled deposition of germanium. To explore the surface chemistry of these alternative precursors, the adsorption and desorption kinetics of (CH3CH2)2GeH2 (DEG) and GeCl4 on Si(111) 7×7 have been examined using laser-induced thermal desorption (LITD), and temperature programmed desorption (TPD) techniques. Fourier transform infrared (FTIR) spectroscopy has also been employed to monitor the decomposition of DEG on porous silicon surfaces. The FTIR spectra revealed that DEG dissociatively adsorbs on porous silicon surfaces at 200 K to form SiH, GeH, and SiCH2CH3 surface species. No spectral features were observed for GeCH2CH3 surface species. The TPD studies following DEG exposures on Si(111) 7×7 observed CH2=CH2 and H2 desorption products at 700 and 800 K, respectively. The production of CH2=CH2 (ethylene) was consistent with a βhydride elimination mechanism from surface ethyl species, i.e. SiCH2CH3(ad) → SiH(ad) + CH2=CH2 (g). Similar TPD experiments following GeCl4 exposures monitored the desorption of only SiCl2 at approximately 920 K. Desorption of SiCl2 indicates that the chlorine on GeCl4 has transferred to the silicon surface. Atomic Ge was also observed to desorb at 1200 K following both DEG and GeCl4 adsorption. LITD experiments measured initial reactive sticking coefficients of So ∼0.05 for DEG and So ∼1.0 for GeCl4 at 200 K. As expected from a precursor-mediated adsorption model, the sticking coefficients decreased versus increasing surface temperature. The sticking coefficients for these germanium containing precursors were higher than the corresponding sticking coefficients for (CH3CH2)2SiH2 and SiCl4. Possible recipes for the CVD or atomic layer controlled deposition of germanium on silicon can be proposed based on the surface chemistry and adsorption and desorption kinetics for DEG and GeCl4.

Diethylsilane on silicon surfaces: Adsorption and decomposition kinetics

The adsorption and decomposition kinetics of diethylsilane (DES), (CH3CH2)2SiH2, on silicon surfaces were studied using laser-induced thermal desorption (LITD), temperature programmed desorption, and Fourier transform infrared (FTIR) spectroscopic techniques. LITD measurements determined that the initial reactive sticking coefficient of DES on Si(111) 7×7 decreased versus surface temperature from S0≊1.7×10−3 at 200 K to S0≊4×10−5 at 440 K. The temperature-dependent sticking coefficients suggested a precursor-mediated adsorption mechanism. FTIR studies on high surface area porous silicon surfaces indicated that DES adsorbs dissociatively at 300 K and produces SiH and SiC2H5 surface species. Annealing studies also revealed that the hydrogen coverage on porous silicon increased as the SiC2H5 surface species decomposed. CH2=CH2 and H2 were the observed desorption products at 700 and 810 K, respectively, following DES adsorption on Si(111) 7×7. The ethylene desorption and growth of hydrogen coverage during ethyl group decomposition were consistent with a β-hydride elimination mechanism for the SiC2H5 surface species, i.e., SiC2H5→SiH+CH2=CH2. Isothermal LITD studies monitored the decomposition kinetics of SiC2H5 on Si(111) 7×7 as a function of time following DES exposures. The first-order decomposition kinetics were Ed=36 kcal/mol and νd=2.7×109 s−1. These decomposition kinetics suggest that the silicon surface catalyzes the β-hydride elimination reaction.

Ammonia decomposition on silicon surfaces studied using transmission Fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) transmission spectroscopy was used to monitor the decomposition of NH3 and ND3 on silicon surfaces. Experiments were performed in situ in an ultrahigh vacuum (UHV) chamber using high surface area porous silicon samples. The FTIR spectra revealed that NH3 (ND3) dissociatively adsorbs at 300 K to form SiH (SiD) and SiNH2 (SiND2) surface species. A comparison of the vibrational absorbances for the SiNH2 and Si2NH surface species indicated that the Si2NH species could account for ≤8% of the surface coverage at 300 K. The infrared absorbances of the SiN–H2 (SiN–D2 ) scissors mode at 1534 cm−1 (1157 cm−1 ), the Si–H (Si–D) stretch at 2077 cm−1 (1510 cm−1 ) and the Si3 –N vibrational modes at 930 and 750 cm−1 were employed to monitor the decomposition of the SiNH2 (SiND2) surface species. As the silicon surface was annealed to 700 K, the FTIR spectra revealed that the SiNH2 (SiND2) surface species gradually decomposed to produce Si3N species and additional SiH species. Above 680 K, the SiH surface species decreased concurrently with the desorption of H2 from the porous silicon surface. The uptake of surface species at various adsorption temperatures was also monitored as a function of NH3 (ND3) exposure time. These studies revealed that similar results were obtained after NH3 (ND3) was adsorbed to saturation coverage at a particular adsorption temperature and after the surface was annealed to the same temperature following a saturation NH3 (ND3) exposure at 300 K.

Kinetics of surface reactions in very low-pressure chemical vapor deposition of Si from SiH4

A steady-state kinetic model for the chemical vapor deposition (CVD) growth of Si films from SiH4 on Si(100) is presented. The only adsorbing species is SiH4 (absence of homogeneous SiH4 dissociation is presumed). Model predictions of surface hydrogen coverage and Si film growth rate as a function of growth temperature ( T ) are compared with literature values for these quantities. The rate of each reaction step is calculated at selected T. Adsorption of SiH4 and decomposition of SiH3 control the growth rate in the high T limit. In the low T limit, SiH4 adsorption is slowest but is not a simple rate determining step. The SiH4 adsorption rate is controlled by the rate of H2 desorption from two surface SiH species, producing dangling bonds.