THE THICKNESS DEPENDENCES OF THE ELECTRONIC AND STRUCTURAL-PROPERTIESOF N-TYPE MICROCRYSTALLINE SILICON FILMS DEPOSITED UNDER VARIOUS POWERS

Highly conductive n-type hydrogenated microcrystalline silicon (mu c-S i:H) films have been prepared by a radio-frequency plasma-enhanced che mical vapour deposition technique in an ultra-high-vacuum deposition s ystem, using a mixture of hydrogen, silane and phosphine gases under a low RF power. The electrical, optical and structural properties of fi lms of various thicknesses have been studied and correlated. Compariso ns between n-type Si:H films deposited under high (120 mW cm(-2)) and low (30 mW cm(-2)) powers have been made. A conductivity as high as 7. 5 S cm(-1) has been achieved for 180 Angstrom thick films. Their cryst allinity was confirmed by transmission electron microscopy and Raman s pectroscopy. Changes in optical absorption at various thicknesses have been studied using photothermal deflection spectroscopy.