High stability of amorphous hafnium–zinc–tin oxide thin film transistors

We investigated amorphous hafnium–zinc–tin oxide (a-HZTO) thin film transistors. HZTO TFTs exhibited good electrical properties with a field effect mobility of 14.33 cm2/V s, a subthreshold swing of 0.97 V/decade, and a high ION/OFF ratio of over 109. Time dependence of the turn-on voltage (VON) shift in HZTO TFTs was reported under negative bias temperature stress measured at 60 °C. HZTO TFTs with 2.0 at. % (Hf element) showed negligible VON shift, compared with −4 V shift in HZTO TFT with 0.5 atomic %. Elemental hafnium may play an important role in improving the bias temperature stability of TFTs due to its high oxygen binding energy. Based on our results, a-HZTO semiconductors are promising candidates as robust channel layers for next generation display applications.