Amorphous transparent electroconductor 2CdO⋅GeO2: Conversion of amorphous insulating cadmium germanate by ion implantation

Amorphous 2CdO⋅GeO2 thin films (optical band gap determined by a Tauc plot; 3.4 eV) prepared by rf sputtering were implanted with H+ or Li+ ions to a dose of 2×1016 cm−2. Direct current conductivities in the specimens at 300 K were increased from 3×10−9 S cm−1 to ∼10 S cm−1 after the implantation. The conductivities in these implanted specimens remained almost constant down to 77 K. No deleterious coloring was perceived after implantation. The Hall mobilities (conduction type; n) in the implanted specimens at ∼300 K were ∼5 cm2 V−1 s−1, which are larger by several orders of magnitude than those in existing amorphous semiconductors. Such a large mobility indicates that the electronic state near the bottom of the conduction band of this amorphous material is extended.