Photoeffects in Fe2O3 sintered semiconductors

Polycrystalline sintered pellets of α-Fe2O3 have been studied by capacitance and photoelectrochemical techniques. The pellets exhibit (i) photocurrent saturation at a given wavelength with increasing applied voltage, (ii) large dark currents at low applied voltage (0.76 μA cm−2 at +0.2 V SCE), (iii) cathodic and anodic photocurrent transients at low levels of monochromatic irradiation, (iv) photocurrent onset at photon energies greater than 2.1 eV, and (v) flat-band potentials of −0.67 V SCE and pH=4. Capacitance measurements followed a Mott-Schottky relationship indicating a predominance of the semiconductor space-charge layer over surface states and electrolyte effects. No degradation of the semiconductor properties could be observed at pH=4.