Field-emission properties of diamond grains grown on textured Fe/Si substrates

Abstract

Diamond grains were produced by the hot-filament chemical-vapor deposition technique using a mixture of CH4/H2 as the synthesis gas. The Si substrates were textured (random pyramids) by chemical etching before growth of diamond grains, because emission of electrons is facilitated at the top of the pyramids. In order to increase the diamond nucleation density, an iron thin film (Fe) was deposited on the textured Si substrate by a radio-frequency plasma sputtering technique. Moreover, partial iron thin films (20% surface coverage) were fabricated for application as field emitter displays using a metal mask. The relationship between the nucleation density and the thickness of the iron films has been investigated by scanning electron microscopy (SEM). The samples were placed in a high-vacuum chamber with a pumping system and the emission current was measured as a function of the applied voltage. The voltage–current (V–I) characteristics were estimated for the field emitter. In order to etch nondiamond components, these samples were etched by O2 and CF4 plasmas. SEM observation revealed that diamond growth is concentrated at the textured Fe/Si area. The nucleation density was 107 cm−2 on the textured Fe/Si area. On the plain textured Si substrate diamond growth could not be observed. Numberless tips were observed on the Fe/Si area after etching. The V–I characteristics revealed a current 10−8 Å at an applied voltage of 1.8 kV. The V–I characteristics could be enhanced by using the textured Fe/Si substrate.