ABSTRACT High‐mobility (>200 cm 2 V −1 s −1 ) transparent top gate amorphous InGaZnO (a‐IGZO) thin‐film transistors (TFTs) are demonstrated using an oxidized Nb capping layer. The Nb capping layer promotes oxygen out‐diffusion from the a‐IGZO channel, which in turn generates oxygen vacancies that serve as shallow donors. The partial capping structure selectively modulates carrier density, where the oxygen vacancy‐rich, low‐resistance region strengthens percolation conduction to enhance mobility, while the uncapped region acts as in‐channel potential barriers to maintain ultra‐low off‐current. The top gate architecture with an Al 2 O 3 /NbO x gate stack strengthens electrostatic control and suppresses drain‐induced barrier lowering (λ DIBL = 6 mV V −1 ). The resulting device achieves a maximum field‐effect mobility of 202 cm 2 V −1 s −1 , a near‐zero threshold voltage, and stable operation under bias stress, while maintaining optical transmittance above 87% in the visible range. This approach provides a scalable and process compatible route for integrating high‐mobility oxide thin‐film transistors into transparent and low‐power display backplanes, enabling the potential replacement of low‐temperature polycrystalline silicon (LTPS) driving transistors in high‐refresh‐rate, high‐brightness active‐matrix organic light‐emitting diode (AMOLED) applications.
Sun et al. (Mon,) studied this question.