Hafnium-Silicon Schottky Barriers: Large Barrier Height on p-Type Silicon and Ohmic Behavior on n-Type Silicon

Schottky-barrier diodes of Hf on p-type Si gave a height φMS = 0.90 eV, which is the largest value of φMS reported to date on Schottky barriers on either p- or n-type Si. Excellent agreement was found between the φMS values determined from current-voltage, activation energy, and capacitance-voltage analyses. This large value of φMS of the Hf-(p)-Si Schottky barrier allows several new applications which were not possible before in the integrated circuit technology, such as clamping of p-n-p transistors and fabrication of enhancement-mode p-channel Schottky gate field-effect transistors. Hafnium deposited on n-type Si (ND≅5×1015 cm−3) gave Ohmic behavior suggesting the validity of the work-function-difference model for the Hf–Si system. Under this assumption, the Schottky-barrier analysis gives the work function of Hf=4.23±0.02 eV.