Room‐Temperature Fabrication of High‐Quality Lanthanum Oxide High‐κ Dielectric Films by a Solution Process for Low‐Power Soft Electronics

Abstract

Abstract High‐quality dielectric films are indispensable for field‐effect electronic devices to provide high electrical performance. However, deposition of high‐quality dielectric films on flexible substrate remains a challenging task, which greatly limits the electrical performance of flexible or organic field‐effect devices. A room‐temperature deep ultraviolet (DUV) irradiation process is proposed for densification of solution‐processed La 2 O 3 films. It is found that room‐temperature DUV‐La 2 O 3 films not only exhibit leakage and dielectric properties that are comparable to those of high‐temperature annealed‐La 2 O 3 films, but also have very smooth and clean surfaces and excellent bending strain tolerance. The fabricated La 2 O 3 films exhibit a wide band gap (5.78 eV), high dielectric constant (12.68), low leakage density (8.8 × 10 −7 A cm −2 at 2 MV cm −1 ), and high breakdown field strength (3.5 MV cm −1 ). Organic thin‐film transistors (OTFTs) based on high‐quality solution‐processed La 2 O 3 gate dielectrics show a low operation voltage (≤3 V), low gate leakage current (<10 −9 A), and high I on / I off ratio (>10 5 ). Based on these room‐temperature‐fabricated high‐performance OTFTs, low‐voltage complementary integrated circuits are successfully fabricated, including complementary inverters and NAND gate circuits. The results demonstrate that room‐temperature DUV‐processed La 2 O 3 films are ideal gate dielectric materials for future flexible and low‐power‐consumption electronic devices.