TY - JOUR
T1 - Different crystal growth mechanisms of Si(001)-(2 × 1):H during plasma-enhanced chemical vapor deposition of SiH3 and SiH2 radicals
T2 - Tight-binding quantum chemical molecular dynamics simulations
AU - Kuwahara, Takuya
AU - Ito, Hiroshi
AU - Kawaguchi, Kentaro
AU - Higuchi, Yuji
AU - Ozawa, Nobuki
AU - Kubo, Momoji
PY - 2013/8/1
Y1 - 2013/8/1
N2 - We use tight-binding quantum chemical molecular dynamics to investigate the crystal growth mechanisms of H-terminated Si(001)-(2 × 1) during plasma-enhanced chemical vapor deposition of SiH3 and SiH2 radicals. We find that crystal growth by SiH3 radical deposition consists of two stages: (1) the first SiH3 radical abstracts a surface-terminating H atom and produces a dangling bond, and (2) a second SiH3 radical is adsorbed on the dangling bond. Thus, at least two SiH3 radicals are required for generating a new Si-Si bond. Interestingly, during SiH2 deposition, a SiH2 radical can be directly adsorbed onto a H-terminated site without H abstraction by another SiH2 radical. Thus, one SiH2 radical is sufficient for generating a new Si-Si bond. This SiH2 radical crystal growth mechanism is different from the SiH3 radical mechanism. The direct adsorption process consists of a two-step chemical reaction: (1) the SiH 2 radical abstracts a surface-terminating H atom and produces a dangling bond and a SiH3 radical, and (2) the SiH3 radical is adsorbed on the dangling bond. In addition, the crystal growth rate for SiH2 radicals is higher than that for SiH3 radicals, because generating one new Si-Si bond requires either a single SiH2 radical or two SiH3 radicals. However, our simulations reveal that SiH2 deposition produces defective Si thin films because many dangling bonds are formed during crystal growth. Compared with SiH2 deposition, SiH3 deposition should therefore produce Si thin films of higher quality.
AB - We use tight-binding quantum chemical molecular dynamics to investigate the crystal growth mechanisms of H-terminated Si(001)-(2 × 1) during plasma-enhanced chemical vapor deposition of SiH3 and SiH2 radicals. We find that crystal growth by SiH3 radical deposition consists of two stages: (1) the first SiH3 radical abstracts a surface-terminating H atom and produces a dangling bond, and (2) a second SiH3 radical is adsorbed on the dangling bond. Thus, at least two SiH3 radicals are required for generating a new Si-Si bond. Interestingly, during SiH2 deposition, a SiH2 radical can be directly adsorbed onto a H-terminated site without H abstraction by another SiH2 radical. Thus, one SiH2 radical is sufficient for generating a new Si-Si bond. This SiH2 radical crystal growth mechanism is different from the SiH3 radical mechanism. The direct adsorption process consists of a two-step chemical reaction: (1) the SiH 2 radical abstracts a surface-terminating H atom and produces a dangling bond and a SiH3 radical, and (2) the SiH3 radical is adsorbed on the dangling bond. In addition, the crystal growth rate for SiH2 radicals is higher than that for SiH3 radicals, because generating one new Si-Si bond requires either a single SiH2 radical or two SiH3 radicals. However, our simulations reveal that SiH2 deposition produces defective Si thin films because many dangling bonds are formed during crystal growth. Compared with SiH2 deposition, SiH3 deposition should therefore produce Si thin films of higher quality.
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U2 - 10.1021/jp4021504
DO - 10.1021/jp4021504
M3 - Article
AN - SCOPUS:84881262524
SN - 1932-7447
VL - 117
SP - 15602
EP - 15614
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 30
ER -