Electron field emitters made of 3-D CuO nanowires on flexible silicon substrate fabricated by heating Cu rods with through silicon: Via process

Cu rods with a diameter of 10 μm on a flexible silicon substrate were fabricated using the through silicon via (TSV) process and chemical mechanical polishing (CMP). The turn-on field and field enhancement factor (β) of the TSV Cu rods were 28.6 V μm^-1 and 1721, respectively. Three-dimensional (3-D) CuO nanowires (NWs) were then grown vertically and laterally on the top and sidewall of the Cu rods via heat treatment in air for various durations. The turn-on field was reduced sharply after CuO NW growth. Longer CuO NWs and higher NW density led to a lower turn-on field. The turn-on fields of samples treated for 0.5, 1, and 5 h were 5.4, 4.9, and 3.5 V μm^-1, and the β values were 2546, 2734, and 4262, respectively. The 3-D CuO NWs are suitable for applications that require a flexible substrate.