Studying of silane thermal decomposition mechanism

Abstract

The mechanism of silane thermal decomposition is investigated in a flow reactor. The time dependencies of silane consumption and disilane formation were compared with those parameters of solid product (aerosol particles) such as concentration, total hydrogen content in solid product, and fraction of hydrogen contained in solid product as polyhydride groups (SiH 2 ) n . Silane loss and gaseous product formation were analyzed using a mass spectrometer. The hydrogen content in solid product was analyzed by the methods of IR-spectroscopy and hydrogen evolution. Based on a simple kinetic scheme we qualitatively explained the experimental dependencies of silane conversion and disilane formation, the effective activation energy of the decomposition process, and the amount of polyhydride groups in the solid product on reaction time and initial silane concentration.

Growth, Thermodynamics, and Electrical Properties of Silicon Nanowires

“…This value is still slightly smaller than the activation energy of 35.4 kcal/mol derived from silicon thin film deposition experiments using silane. 31,32 The fact that the activation energy of radial growth is still smaller than the nominal activation energy for Si thin film deposition could possibly be explained by the catalytic effect of a Au contamination of the nanowire surface. 24 Another attractive precursor for low temperature CVD is disilane, Si 2 H 6 .…”

“…Silicon thin film deposition experiments gave an activation energy of 28.4 kcal/mol (1.23 eV) compared to 35.4 kcal/mol (1.53 eV) for silane. 31,32 The higher reactivity of disilane compared to silane represents its main advantage, as it allows for Si wire growth at much lower pressures compared to that for silane. The lower pressures are particularly important for the in situ observation of Si nanowire growth, for example, in a transmission electron microscope (TEM).…”

Thermochemistry and Kinetics of Silicon Hydride Cluster Formation during Thermal Decomposition of Silane

“…Nijhawan et al 37,38 have made measurements of particle formation in two different low-pressure thermal CVD reactors. Onischuk and co-workers [39][40][41] have analyzed the hydrogen content and bonding of particles formed during thermal decomposition of silane, as well as the overall kinetics and dependence on reaction conditions. They found that the hydrogen-to-silicon ratio in the solid product ranged from 0.1 to 0.5 and decreased with increasing temperature and increasing reaction time.…”

Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry

“…The experimental works in the field, on the other hand, have a much lower degree of detail. These works are typically limited to measurements of silanes with no more than three or four silicon atoms and have a lack of differentiation between isomers [13,14,20,32]. Some experimental works include measurements of particle properties, like size distribution [13,15,16,33] and hydrogen content [13,15].…”

“…Similar measurement techniques were used by Slootman and Parent [14] and by Odden et al [20] also using GC combined with a TCD for measuring concentrations of H 2 , SiH 4 , Si 2 H 6 and Si 3 H 8 during thermal pyrolysis of SiH 4 diluted in hydrogen. Further, quadrupole mass spectrometry has been applied to detect higher order silanes (with up to five silicon atoms) in the products of plasma-enhanced deposition of amorphous silicon from monosilane [46][47][48][49], in products of thermal decomposition of monosilane diluted in argon [13,32,50], and in products of pyrolysis of disilane [44]. Vacuum ultraviolet (VUV) photoionization combined with time of flight (TOF) MS have been applied for measuring gas-phase products of pyrolysis of SiH 4 and Si 2 H 6 [51][52][53][54], and it has proven capable of detecting higher order silanes with up to ten silicon atoms [52,53].…”