Effect of La Addition on the Electrical Characteristics and Stability of Solution-Processed LaInO Thin-Film Transistors With High-${k}$ ZrO2Gate Insulator

Abstract

In this paper, solution-processed ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thin films are used to be as insulting layers for lanthanum indium oxide (LaInO) thin-film transistors (TFTs) with different La doping contents. The influence of La addition on the electrical properties and stability under bias stress and temperatures stress for LaInO TFTs is investigated in detail. With the improvement of La doping contents, the saturation mobility (μ) decreases from 48.8 to 32.7 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> · V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and the threshold voltage (VT) increases from 1.12 to 1.76 V. When La doping concentration is 10 mol%, LaInO TFT has a small subthreshold swing of 0.12 V/dec. Meanwhile, the stability is improved obviously. It is attributed to the strong bonding strength of La-O relative to that of In-O, resulting in the reduction of trap states. X-ray photoelectron spectroscopy shows that the generation of oxygen vacancies can effectively be suppressed by La addition. The calculation of density of states and the measurement of the capacitance-voltage can also further confirm that the density of trap states is decreased by La addition, and thus the stability of LaInO TFTs can get an obvious improvement.