PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION OF NANOCRYSTALLINE SILICON THIN FILMS

THE RECENT OBSERVATION OF EFFICIENT VISIBLE LUMINESCENCE FROM NANOMETER-SIZED SILICON CRYSTALLITES HAS GENERATED A GREAT DEAL OF EXCITEMENT IN THE SEMICONDUCTOR COMMUNITY. THE EMISSION OF LIGHT ABOVE THE BANDGAP OF SILICON IS GENERALLY ATTRIBUTED TO QUANTUM CONFINEMENT OF CARRIERS IN CRYSTALLITES WITH DIMENSIONS LESS THAN 5 NM. THIS RESEARCH PROJECT EXAMINES PLASMA-ENHANCED CHEMICAL VAPOR DEPOSITION AS A METHOD OF PRODUCING NANOCRYSTALLINE SILICON THIN FILMS EXHIBITING VISIBLE LUMINESCENCE. HEAVILY DOPED MICROCRYSTALLINE FILMS GROWN BY PLASMAENHANCED CHEMICAL VAPOR DEPOSITION HAVE BEEN STUDIED FOR MANY YEARS FOR USE IN AMORPHOUS SILICON PHOTOVOLTAICS. THE MICROCRYSTALLINE FILMS CONSIST OF CRYSTALS WITH TYPICAL GRAIN SIZES LESS THAN 10 NM SURROUNDED BY AN AMORPHOUS SILICON MATRIX. IT HAS BEEN SHOWN THAT REMOVAL OF THE AMORPHOUS MATRIX LEAVES NANOCRYSTALLINE SILICON WITH VISIBLE LUMINESCENCE. UNDOPED P AND N TYPE MICROCRYSTALLINE FILMS ARE BEING GROWN BY PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION WITH SUBSEQUENT ETCHING OF THE AMORPHOUS MATRIX TO LEAVE NANOCRYSTALLINE FILMS. THE PHOTOLUMINESCENCE AND STABILITY OF THE DEPOSITED FILMS ARE BEING EXAMINED WITH THE ULTIMATE GOAL OF PRODUCING LIGHT EMITTING DIODES ON GLASS SUBSTRATES FOR LARGE AREA FLAT PANEL DISPLAY APPLICATIONS.