Effect of sputtering pressure on pulsed-DC sputtered iridium oxide films

Abstract

This paper reports the influence of the sputtering pressure, ranging from 5 to 50 mTorr using a mixture of Ar and O 2 (1:1), on the properties of the IrO x films deposited by pulsed-DC reactive sputtering. The sputtered IrO x films were characterized by surface analysis methods (scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectrometry, X-ray diffraction), four-point probe method, and electrochemical techniques (cyclic voltammetry and electrochemical impedance spectroscopy). The optimal sputtering pressure was identified to be 5 mTorr at which the activated IrO x film showed highest charge storage capacity of 28.3 mC/cm 2, which was almost three times higher than that of samples deposited at 50 mTorr. The IrO x films deposited at low pressure showed excellent mechanical electrical and electrochemical characteristics and hence can be recommended as an ideal stimulation electrode material for neuroprosthetic applications.