INFLUENCE OF AL AND P DOPING ON OPTICAL AND ELECTRICAL-PROPERTIES OF ION-BEAM SYNTHESIZED SIC

Ion implantation of 3 x 10(17) C/cm2 at 25 keV into Si has been applie d to synthesize thin films of SiC. The starting material, 130 nm thick layers of Si on sapphire substrates, was held at 900-degrees-C during ion implantation. After annealing at 1300-degrees-C for 15 min the re sulting SiC films consist of crystallites of approximately 10-30 nm di ameter. Dopant species, P and Al for n- and p-type doping, have been i ntroduced by ion implantation either before and after synthesis of SiC . Optical and electrical measurements have been performed in order to characterize the films. As concluded from nearly identical absorption characteristics, the crystallization behaviour of both types of specim ens is fairly the same, indicating that the presence of dopants does n ot influence the reordering of the crystal matrix. Also the electrical properties of the doped specimens do not depend on the sequence of pr eparation steps. The experimental results will be discussed in some de tail by considering the structural properties of the polycrystalline S iC films.