Controlled orientation and microstructure of p-type SnO thin film transistors with high-k dielectric for improved performance

Abstract

Despite its relatively high hole mobility, the electrical performance of p-type SnO thin-film transistors (TFTs) lags behind that of n-type oxide TFTs. In this study, we present an approach to enhance the performance of p-type SnO TFTs by utilizing an atomic-layer-deposited SnO/high-k structure, with crystalline HfO2 (c-HfO2) serving as a high-k dielectric. However, the grain boundaries on the c-HfO2 surface influenced the microstructure and orientation of the SnO layer, resulting in a random orientation and surface roughening. To address this issue, we modified the c-HfO2 surface with an amorphous ultrathin Al2O3 layer to eliminate the grain boundaries on the deposition surface. This enabled the alignment of the (00l) SnO planes parallel to the substrate surface and provided a smooth surface. Moreover, the introduction of ultrathin Al2O3 into SnO/high-k stacks substantially improved the electrical performance of p-type SnO TFTs. Our findings highlight the potential of integrating van der Waals semiconductors with high-k dielectrics, facilitating opportunities for advanced device applications.