Current density–voltage and admittance characteristics of hydrogenated nanocrystalline cubic SiC/crystalline Si heterojunction diodes prepared with varying H2 gas flow rates

Abstract N-doped hydrogenated nanocrystalline cubic SiC (nc-3C-SiC:H) thin films were deposited on p-type crystalline Si (c-Si) substrates by hot-wire chemical vapor deposition from a SiH 4 /CH 4 /H 2 /N 2 gas mixture. The current density–voltage and the admittance characteristics of the nc-3C-SiC:H/c-Si heterojunction diodes were investigated. As the H 2 gas flow rate ( F (H 2 )) increased from 25 to 100 sccm, the ideality factor and saturation current density deceased from 1.87 to 1.47 and 1.6 × 10 −7 to 9.9 × 10 −9  A/cm 2 , respectively. However, they increased to 1.82 and 3.0 × 10 −7  A/cm 2 , respectively, when F (H 2 ) was further increased to 1000 sccm. The relaxation time, evaluated from the admittance characteristics, decreased from 2.9 × 10 −5 to 2.4 × 10 −6  s with an increase in F (H 2 ). The apparent built-in voltage, evaluated from the capacitance–voltage characteristics, decreased from 1.05 to 0.60 eV. These findings were mainly caused by interfacial defects, generated by a high density of H radicals during the nc-3C-SiC:H deposition process. The interfacial defect density increased with an increase in F (H 2 ), resulting in deterioration of the diode characteristics.