n-type electrical conduction in transparent thin films of delafossite-type AgInO2

Thin films of AgInO2 were prepared to find a transparent and n-type conducting oxide with a delafossite structure. This is a candidate material for fabricating a pn junction with the recently found p type conducting and transparent CuAlO2 delafossite. Nondoped and 5% Sn-doped thin films were deposited on a silica glass substrate by radio-frequency sputtering. The crystalline phase in the films was identified to be the delafossite structure by x-ray diffraction and chemical composition was confirmed to be an Ag/In ratio = 1.00/0.97 by inductively coupled plasma emission spectroscopy. The optical band gap was estimated from absorption spectra to be similar to 4.4 eV, and the thin films were transparent up to near ultraviolet region. Electrical conductivities of the nondoped and 5% Sn-doped AgInO2 films at room temperature were 1x10(-5) and 6x10(0) S cm(-1), respectively. Measurements of Hall voltage and Seebeck coefficient (-50 mu V K-1) suggested the conduction in the Sn-doped film to be n type. Carrier concentration and Hall mobility in the doped film were 2.7x10(19) cm(-3) and 0.47 cm(2) V-1 s(-1), respectively. (C) 1998 American Institute of Physics.