In-Situ and Ion Implantation Nitrogen Doping on Near Stoichiometric a-SiC:H Films
Keywords:SiC, Doping, PECVD, amorphous semiconductor
In this work we study the nitrogen n-type electrical doping of a-Si0.5C0.5:H films obtained by plasma enhanced chemical vapor deposition (PECVD) utilizing and comparing two doping techniques: in-situ (during the material growth) and ion implantation. The in-situ doped a-SiC:H films were obtained adding different amounts of N2 to the precursor gas mixture. For ion implantation four different nitrogen implanted concentrations were studied (between 1018 and 1021 atoms/ cm3) using multiple energies and doses to define a homogeneously doped layer. The doping experiments are carried out on a-SiC:H samples that present different structural order. The results show that high levels of electrical conductivity can be obtained with ion implantation technique. For in-situ technique the doping effect is also observed but must be improved in order to attain higher electrical conductivities. In the best case the room temperature dark conductivity for the sample implanted with 1021 nitrogens/cm3 was ~10-7 (Ω.cm)-1 and the activation energy was 0.2 eV. For in-situ doping the electrical dark conductivity reached values near 10-10 (Ω.cm)-1 at high temperatures and the activation energy was ~0.6 eV. Despite of the apparent low values of the electrical conductivity, these results are promising because we are dealing with a wide gap material and the doping processes are still not optimized.