Electrical Properties and Interface States of Rare-Earth Metal Ytterbium Schottky Contacts to p-Type InP

The electronic parameters and interface state properties of Yb/p-InP Schottky diode have been investigated by current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G-V-f) measurements at room temperature. The barrier height and ideality factor of the Yb/p-InP Schottky diode are found to be 0.68 eV (I-V)/0.79 eV (C-V) and 1.24, respectively. As well, the values of barrier heights, ideality factors and series resistance are estimated by Cheung and Norde methods are compared. Under forward bias conditions, ohmic and space charge limited conduction (SCLC) mechanisms are identified at low and higher voltages, respectively. The C-V characteristics of the Yb/p-InP Schottky diode are also measured at different frequencies at room temperature. Further, the C-f and G-f measurements of the Yb/p-InP Schottky diode are performed at various biases. The interface state density N-ss and relaxation time tau of the diode are estimated from the C-f and G-f measurements. The N-ss and the tau show a decrease with bias from the top of the valence band toward the midgap. The profile of series resistance dependent on frequency and voltage confirms the presence of interface states in Yb/p-InP Schottky structure.