Improved Negative Bias Stability of Sol–Gel-Processed SnO₂ Thin-Film Transistors with Vertically Controlled Carrier Concentrations

Abstract

This study investigates the performance of SnO2 thin-film transistors (TFTs) fabricated with vertically controlled carrier concentrations using a sol–gel method. In the proposed fabrication method, thin Al layers are deposited on SnO2 surfaces to control carrier concentrations. The deposited Al layers are converted into Al2O3 islands on the SnO2 surfaces, functioning as Al3+ dopant sources after an additional annealing process. Using this process, an oxygen-vacancy-less surface regime inside SnO2 semiconductors is successfully formed. It is demonstrated that this morphology significantly reduces bias stress instability by inhibiting trap and de-trap events at the surface of the back channel of TFTs. The fabricated SnO2 TFTs with oxygen-vacancy (VO)-less surfaces demonstrate a field-effect mobility of 8.49 cm2/Vs and a threshold voltage shift of only −3.84 V during negative bias tests. However, compared to other existing bias stress stable metal-oxide semiconductors, the proposed SnO2 TFTs exhibit only a 3.2% loss in field-effect mobility, alongside improved negative bias stability.

Dual Role of AgNO3 as an Oxidizer and Chloride Remover toward Enhanced Combustion Synthesis of Low-Voltage and Low-Temperature Amorphous Rare Metal-Free Oxide Thin-Film Transistors

“…Furthermore, solution-based TFTs have shown good mobility, low subthreshold swing ( SS ), large on/off current, and good stability in recent reports. − However, despite advancements, solution-processed metal oxides still have issues with film quality due to defects, unlike their vacuum-processed counterparts. Sol–gel synthesis is the conventional route used to prepare solution precursors for forming amorphous oxide films, but it usually requires temperatures higher than 450 °C to form the metal oxide. − Thus, low-temperature processing methods were developed to decrease the fabrication temperature and make solution processing compatible with flexible substrates that have low melting points. In 2011, Kim et al introduced solution combustion synthesis (SCS) for thin-film fabrication, a technique that uses the heat of combustion to create higher-quality metal oxides .…”

UV/Ozone-Treated and Sol–Gel-Processed Y2O3 Insulators Prepared Using Gelation-Delaying Precursors

“…Therefore, metal oxides with higher mobility, transmittance, thermal stability, and process compatibility are used for fabricating CMOS devices. Metal oxides can be used to fabricate various devices such as conductors, semiconductors, and insulators [7][8][9][10][11][12][13]. Dielectric materials are used as electrical insulators as they are poor conductors of electricity.…”

“…Dielectric materials are used as electrical insulators as they are poor conductors of electricity. They are critical components in electronic devices, including transistors, resistive switching memory devices, ferroelectric memory devices, neuromorphic devices, and conventional data-storage devices such as flash memory devices [9][10][11][14][15][16][17].…”