Electrical characterization of ultra-shallow n⁺p junctions formed by AsH₃ plasma immersion implantation

Electrical characteristics of ultra-shallow (̃90 nm) n⁺p junctions fabricated using plasma immersion implantation of arsenic ions are investigated. With the arsenic source, a more uniform doping profile was obtained. In addition, both forward and reverse current-voltage (IV) characteristics at operation temperature ranging from 100 to 450 K were measured. Results show that the ideality factor varies from unity to two indicating both diffusion and generation-recombination (GR) processes are important in these devices. The ideality factor is found to fluctuate with the temperature due to discrete trap centers in the junction. Annealing has profound effect on the reverse diode characteristics. For fully activated sample, the IV relationship in the reverse region essentially follows a power law, i.e. I∝ V^m. The power index (m) is about 3 and almost remains unchanged at different temperatures.