Physical properties of transparent conducting Cd-Te-In-O thin films Outlining a thermodynamic system for transparent conducting oxides

摘要

Cd-Te-In-O thin films are grown by pulsed laser deposition using a composite target of CdTe powder embedded in an indium matrix. Oxygen pressures range from 2.00 to 6.67 Pa at a substrate temperature of 420 ℃. The structure, optical transmission and sheet resistance of the films are measured. Substitutional compounds with In_(2-2x)(Cd,Te)_(2x)O_3 stoichiometry are found at high oxygen pressures. A ternary phase diagram of the CdO-In_2O_3-TeO2 system shows the relationship between the structure and the stoichiometry of the films. To evaluate film performance, a figure of merit is proposed based on the relationship between the integral photonic flux and the sheet resistance. The best figure of merit values corresponds to a sample prepared at 3.8 Pa O_2 that consists of (In_2O_3)_(0.3)(CdTe_2O_5)_(0.7) and exhibits an optical band gap of 3.0 eV. This sample is a suitable substrate for electrodeposition due to its good electrochemical stability.