R. Ji

Application of electron cyclotron resonance chemical vapour deposition in the preparation of hydrogenated boron-doped Sic films

Abstract Hydrogenated silicon carbide (Sic: H) films were deposited using the electron cyclotron resonance (ECR) chemical vapour deposition (CVD) technique from a mixture of methane, silane and hydrogen using diborane as the doping gas. The effects of changes in the microwave power on the deposition rate and optical bandgap were investigated, and variations in the photoconductivity and dark conductivity and activation energy were studied in conjunction with film analysis using the Raman scattering technique. The conductivity increased rapidly to a maximum, followed by rapid reduction at high microwave powers. The ratio ([sgrave]ph/[sgrave]d) of the photoconductivity to the dark conductivity peaked at microwave power of about 600 W. Under conditions of high microwave power, Raman scattering analysis showed evidence of the formation and increase in the silicon microcrystalline and diamond-like phases in the films, the former of which could account for the rapid increase and the latter the subsequent decreas...

Some effects of phosphorus doping in SiC:H films prepared using ECR-CVD

Abstract This paper reports the deposition of hydrogenated silicon carbide (SiC:H) films using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique. Using this technique, SiC:H films were prepared from a mixture of methane, silane and hydrogen, with phosphine as the doping gas. The effects of changing the phosphine fraction on the optical bandgap, activation energy and conductivity were investigated in films deposited at two different microwave powers of 150 and 600 W, respectively. The results showed that the deposition conditions strongly influence the structural, optical and electrical properties of the SiC:H films. In films deposited at low and high microwave powers, phosphorus doping has the effect of enhancing the formation of the silicon microcrystalline phase. In films which contain a strong silicon microcrystalline phase, the optical bandgap remained relatively constant while the conductivity increased rapidly followed by saturation. Correspondingly, the activation energy decreased and saturated suggesting an effect due to dopant saturation. The results showed that good phosphorus doping efficiency can be obtained in SiC:H films deposited at high microwave power.

Preparation of n-type SiC:H using ECR—CVD: some effects of microcrystallite silicon formation induced by phosphorus doping and microwave power

Abstract This paper reports the deposition of hydrogenated silicon carbide (SiC:H) films using the electron cyclotron resonance chemical vapour deposition (ECR—CVD) technique. Using this technique, SiC:H films were prepared from a mixture of methane, silane and hydrogen, with phosphine as the doping gas. The effects of changing the phosphine fraction on the optical bandgap, activation energy and conductivity were investigated in films deposited at two different microwave powers of 150 and 600 W, respectively. Additionally, the effects of changes in the microwave power (from 150 to 900 W) on the characteristics of the phosphorus-doped films were also investigated. Raman scattering analysis shows that increase in the microwave power and high phosphorus doping fractions have the effect of enhancing the formation of the silicon microcrystalline phase in the films. Films having a strong silicon microcrystalline phase exhibit relatively small changes in the optical bandgap. The film conductivity increased rapidly followed by saturation as the microwave power or phosphorus doping fraction is increased. Correspondingly, the activation energy decreased and saturated suggesting an effect due to dopant saturation. The results showed that good phosphorus doping efficiency can be obtained in SiC:H films deposited at high microwave power. Results from IR absorption measurements suggest that hydrogen is bonded to silicon in the Si-H stretching mode and to carbon in the sp 3 CH n rocking/wagging and bending modes in films deposited at high microwave powers.

The effects of process pressure and microwave power on the properties of boron-doped SiC: H films prepared using the ECR-CVD technique

Hydrogenated amorphous silicon carbide films (a-SiC:H) were deposited from a mixture of methane, silane and hydrogen, with diborane as the doping gas, using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique. The effect of the microwave power on the deposition rate was studied at two different process pressures (4 mTorr and 8 mTorr), and variations in the photoconductivity and dark conductivity were investigated in conjunction with film analysis using the Raman scattering technique. Samples deposited at both process pressures showed a rapid increase in the conductivity to a maximum, followed by a drastic reduction at high microwave powers. The ratio of the photoconductivity to the dark conductivity (σph/σd) peaked at microwave powers of about 550 W and 450 W for samples deposited at 8 mTorr and 4 mTorr respectively. Under conditions of high hydrogen dilution and increasing microwave power, Raman scattering analysis showed evidence of the formation and increase of microcrystalline silicon and diamond-like phases in the films, the former of which could account for the rapid increase and the latter for the subsequent decrease in the conductivity.

Some effects of boron and phosphorus doping on the properties of SiC:H films prepared using electron cyclotron resonance-chemical vapor deposition

Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapor deposition method from a mixture of methane, silane, and hydrogen, and using diborane and phosphine as doping gases. The effects of changes in the diborane and phosphine levels on the deposition rate, optical band gap and conductivity were investigated. In the case of boron-doped films, there is evidence from Raman scattering analysis to show that films deposited at a low microwave power of 150 W were all amorphous and the band gap decreases as the diborane level is increased, whereas films deposited at a high microwave power of 800 W at low diborane levels are highly conductive and contain the silicon microcrystalline phase. These films become amorphous as the diborane level is increased, while the optical band gap remains relatively unaffected throughout the entire range of diborane levels investigated. In the case of phosphorus-doped films, Raman scattering analysis showed that the deposition conditions strongly influence the structural, optical, and electrical properties of the SiC:H films. Unlike boron doping, doping with phosphorus can have the effect of increasing the silicon microcrystalline phase in the SiC:H films, which were prepared at low (150 W) and high (600 W) microwave powers. Films prepared at high microwave power showed only small variations in the optical band gap, suggesting that good phosphorus doping efficiency can be achieved in films that contain the silicon microcrystalline phase (mc-SiC:H).Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapor deposition method from a mixture of methane, silane, and hydrogen, and using diborane and phosphine as doping gases. The effects of changes in the diborane and phosphine levels on the deposition rate, optical band gap and conductivity were investigated. In the case of boron-doped films, there is evidence from Raman scattering analysis to show that films deposited at a low microwave power of 150 W were all amorphous and the band gap decreases as the diborane level is increased, whereas films deposited at a high microwave power of 800 W at low diborane levels are highly conductive and contain the silicon microcrystalline phase. These films become amorphous as the diborane level is increased, while the optical band gap remains relatively unaffected throughout the entire range of diborane levels investigated. In the case of phosphorus-doped films, Raman scattering analysis showed that the deposition...

Microwave power effects on the properties of phosphorus-doped SiC:H films prepared using ECR-CVD

Abstract There has been a growing interest in hydrogenated silicon carbide films (SiC:H) prepared using the electron cyclotron resonance-chemical vapour deposition (ECR-CVD) technique. Using the ECR-CVD technique, SiC:H films have been prepared from a mixture of methane, silane and hydrogen, with phosphine as the doping gas. The effects of changes in the microwave power (from 150 to 900 W) on the film properties were investigated in a series of phosphorus-doped SiC:H films. In particular, the changes in the deposition rate, optical bandgap, activation energy and conductivity were investigated in conjunction with results from Raman scattering and Fourier transform infra-red (FTIR) analysis. It was found that increase in the microwave power has the effect of enhancing the formation of the silicon microcrystalline phase in the amorphous matrix of the SiC:H films. This occurs in correspondence to a rapid increase in the conductivity and a reduction in the activation energy, both of which exhibit small variations in samples deposited at microwave powers exceeding 500 W. Analysis of IR absorption results suggests that hydrogen is bonded to silicon in the SiH stretching mode and to carbon in the sp 3 CH n rocking/wagging and bending mode in films deposited at higher microwave powers.

Microwave power dependence of the optical and structural properties of boron and phosphorus-doped SiC:H films prepared using ECR-CVD

Abstract Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, and using diborane and phosphine as doping gases. The effects of changes in the microwave power on the deposition rate and optical bandgap were investigated, and variations in the photo- and dark-conductivities were studied in conjunction with film analysis using the Raman scattering technique. In the case of boron-doped samples, the conductivity increased rapidly to a maximum, followed by rapid reduction at high microwave powers. The ratio of the photo- to dark-conductivity ( σ ph / σ d ) peaked at microwave power of ∼600 W. Under conditions of high microwave power, Raman scattering analysis showed evidence of the formation and increase in the silicon microcrystalline and diamond-like phases in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity. In the case of phosphorus-doped SiC:H samples, it was found that increase in the microwave power has the effect of enhancing the formation of the silicon microcrystalline phase in the films which occurred in correspondence to a rapid increase in the conductivity. The conductivity increase stabilised in samples deposited at microwave powers exceeding 500 W probably as a result of dopant saturation. Results from Raman scattering measurements also showed that phosphorus doping has the effect of enhancing the formation of the silicon microcrystals in the film whereas the presence of boron has the effect of preserving the amorphous structure.

A Raman and photoconductivity analysis of boron-doped SiC : H films deposited using the electron cyclotron resonance method

Hydrogenated amorphous silicon carbide films (a-SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition technique from a mixture of methane, silane and hydrogen, with diborane as the doping gas. The effect of the microwave power on the deposition rate were studied, and variations in the photo and dark conductivities were investigated in conjunction with film analysis using the Raman scattering technique. The conductivity increases rapidly to a maximum, followed by rapid reduction at high microwave powers. The ratio of the photo to dark conductivity, σph/σd, peaks at microwave powers of ∼600 W. Under conditions of high hydrogen dilution and increasing microwave power, Raman scattering analysis showed evidence of the formation and increase of microcrystalline silicon and diamond-like components in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity.

Doping and microwave power effects on the properties of a-SiC:H and μc-SiC:H films prepared using ECR-CVD

Abstract Hydrogenated amorphous silicon carbide films (a-SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, with diborane as the doping gas. Using two different process pressures (4 and 8 mTorr), the effect of the microwave power on the deposition rate were studied, and variations in the photo and dark conductivities were investigated in conjunction with film analysis using the Raman scattering technique. Samples deposited at both pressures showed rapid increase in the conductivity to a maximum, followed by drastic reduction at high microwave powers. The ratio of the photo to dark conductivity (σ ph /σ d ) peaks at microwave powers of ~ 600 and 450 W for samples deposited at 8 and 4 mTorr. respectively. Under conditions of high hydrogen dilution and increasing microwave power, Raman scattering analysis showed evidence of the formation and increase of microcrystalline silicon and diamond-like phases in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity. Preliminary investigations of the effect of changes in the diborane levels show that films deposited at a low microwave power of 150 W were all amorphous whereas those deposited at a high microwave power of 800 W contain microcrystalline silicon inclusions and became amorphous as the diborane level is increased.

Influence of boron doping on the properties of amorphous and microcrystalline SiC films prepared using ECR-CVD

Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance plasma chemical vapor deposition (ECR-CVD) method from a mixture of methane, silane, and hydrogen, with diborane as the doping gas. The effect of changes in the percentage of the diborane to reactant gas mixture on the deposition rate, optical bandgap, and photoconductivity were investigated. There is evidence from Raman scattering analysis to show that films deposited at a low microwave power of 150 W were all amorphous and the bandgap decreases as the diborane level is increased whereas films deposited at a high microwave power of 800 W at low diborane levels are highly photoconductive and contain microcrystalline silicon inclusions. These films become amorphous as the diborane level is increased, while the optical bandgap remains relatively unaffected throughout the entire range of diborane levels investigated. The effect of the microwave power was also investigated. The conductivity increases rapidly to a maximum, followed by rapid reduction at high microwave powers. Raman scattering analysis showed evidence of the formation and increase of microcrystalline silicon inclusions and diamond-like components in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity.