SiC and Si Quantum Dots Co-Precipitated Si-Rich SiC Film with n- and p-Type Dopants Grown by Hydrogen-Free PECVD

The co-precipitation of Si and SiC quantum dots (QDs) in Si-rich silicon carbide (Si-rich SiC) films with n-type and p-type dopants is preliminarily demonstrated with low-temperature plasma enhanced chemical vapor deposition and high-temperature annealing. With specific hydrogen-free recipe of argon diluted silane (SiH₄) and pure methane (CH₄), the composition ratio x of Si-rich Si_xC_1-x film can be varied from 0.74 to 0.67 by tuning the flow rate of g = [CH₄]/([CH₄]+[SiH₄]) from 40% to 60%. Both SiC-QDs and Si-QDs can only be precipitated by annealing the Si-rich Si_0.69C_0.31 grown with g = 50% at 1050°C. The Si_0.69C_0.31 transfers into a nano-crystallized matrix with buried SiC-QDs and Si-QDs at diameters of 2.5 nm and 4.5 nm, respectively. The co-precipitated SiC-QDs and Si-QDs in Si-rich Si_0.69C_0.31 shrink the linewidth of c-Si related Raman scattering peak at 520 cm⁻¹ from 87 cm⁻¹ to 42 cm⁻¹, and up-shift the Si-C transverse optical (TO) and longitudinal optic (LO) mode related Raman scattering peaks to 796 cm⁻¹ and 970 cm⁻¹, respectively. Decreasing the flow rate from g = 60% to g = 50% improves the conductivity of Si-rich Si_xC_1-x film by more than one order of magnitude. At optimized recipe of g = 50%, the resistivities of p-type and n-type Si_xC_1-x films are reduced to 2 × 10¹ Ω-cm and 3.1 × 10⁻¹ Ω-cm, respectively.

Source:IOPscience

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