A photoelectrochemical study of the GdMg hydride switchable mirror

A significant chemical stability has allowed us to perform photoelectrochem ical measurements on the semiconducting state of the GdMg hydride system. W ith electrical impedance spectroscopy we confirm that GdMg hydride in the t ransparent state is an a-type semiconductor. The donor density was estimate d to be 5 x 10(21) cm(-3). Impedance measurements give information about th e potential distribution at the semiconductor/solution interface. Photocurr ent was observed in the transparent state. It is proposed that photoanodic etching of the GdMg hydride at high light intensities occurs along grain bo undaries, leading to inhomogeneous destruction of the film, (C) 2001 The El ectrochemical Society.