Homo-epitaxial Si absorber layers grown by low-temperature ECRCVD

摘要

We studied the homo-epitaxial growth of Si absorber layers at temperatures of 420-560℃ by electron-cyclotron resonance chemical vapour deposition. We deposited the Si films at rates of 15 nm min~(-1) on (100)-, (311)-, (111)- and multicrystalline Si wafers. Both substrate temperature and orientation have a pronounced influence on the structural quality. On Si(100) substrates films grew epitaxially above 480℃ and are of excellent crystallographic quality up to thicknesses of 2.5 μm. On Si(311) the epitaxy breaks down rapidly by the formation of polycrystalline regions. On Si(111) the films are always fine polycrystalline. Using multicrystalline substrates the quality of the films is related to the orientation of the grains ranging from excellent epitaxy to pure fine polycrystalline growth. The electrical properties of the intentionally undoped films grown on Si(100) are discussed in relation to the crystal quality.