The electrical properties of in-situ doped polycrystalline silicon thin films grown by electron cyclotron resonance chemical vapor deposition at 250°C

The phosphorus doped polycrystalline silicon thin films were grown by Electron Cyclotron Resonance Chemical Vapor Deposition (ECR-CVD) at 250 degrees C. The doping gas PH3 was in-situ added with SIH4 gas during the films deposition. All films were deposited with 90% hydrogen dilution ratio. The resistivity of the films is varied from 0.2 to 7 Omega-cm and decrease as the PH3/SiH4 gas ratio increase from (3/100 to 7/100). From the SIMS data, the doping concentration is all about 10(20)cm(-3). The activation energy is decreased from 0.35 eV to 0.12 eV as the dopant concentration increased from 0.8x10(20)cm(-3) to 4.7x10(20)cm(-3). From the Hall measurements, the carrier mobility is about 2 similar to 4 cm(2)/V.sec, and the carrier concentration is the 0.5 similar to 1% of the dopant concentration. The gain boundary trap density predicted by the trapping model is about 4x10(13)cm(-2).