Field Effect Properties of Phosphorus Doped CdS Single-Crystal Nanoribbon via Co-Thermal-Evaporation

High quality Phosphorus doped (P-doped) CdS nanoribbons (NRs) were synthesized with different doping levels by co-thermal-evaporation. The field-effect-transistors based on as-synthesized nanoribbons were fabricated successfully too. The as-synthesized Phosphorus doped CdS nanoribbons are wurtzite structure and grow along the [110] orientation. The XRD patterns of doped CdS nanoribbons show obviously shifting to left with the increasing of a and c lattice parameters when percent of dopant is up to 3.18%. The contact of Phosphorus-doped CdS nanoribbons with the electrodes was found to be ohmic contacts, which present the approximate linear relations between source-drain current versus voltage measured by two terminal measurements. It is noted that the characterization of Vg-dependent current versus bias voltage curves demonstrates the n-type semiconductors of as-prepared CdS nanoribbons due to self-compensation effects. The electron mobility of two levels P-doped CdS nanoribbons is calculated to be 175 cm2/Ns and 1.58 cm2/Vs, respectively. The conductance of the higher doping level is three magnitudes larger than that of the lower one nearly. Moreover, the increasing of electronic carriers concentration make the gap between the Fermi level and the conduction band minimum is lower comparing to the intrinsic CdS Nanoribbons.