Abstract
Silicon wafers of p and n-types of 1 to 10 ohm-cm resistivity were implanted with nitrogen ions employing Plasma Immersion Ion Implantation (PIII) technique. Implantation were carried out at three doses corresponding to low (approximately 10
/cm
), moderate (approximately 10
/cm
) and high (approximately 10
/cm
) dose regimes. Metal-silicon devices were fabricated using conventional semiconductor processing techniques. One set of the samples was annealed in forming gas ambient. Electrical characterization was done on all the devices. Change in reverse and forward current was observed with dose of implanted ions. The barrier height of the n- type sample decreases with increase in implanted ion dose, where as in the case of p-type silicon, barrier height was found increasing with dose. At high doses the top layer of both n and p-type silicon become nitrogen rich and exhibits optical properties different from that of unimplanted silicon as measured by ellipsometry. With the nitrogen rich layer, the device behaved like metal-insulator-silicon structure whose electrical characteristics have been studied. Sputtering effects of the nitrogen ions during implantation were also studied.