Study On The Stability Of Metal-Oxide Thin-Film Transistors

In the era of information,the transmission of information is crucial.According to statistics,in the total amount of information obtained by human sensory organs,the proportion of vision is more than 80%.Therefore,as a bridge of the vision and various information,the display technology has received great attention.The mainstream display on the market today is still Liquid Crystal Display?LCD?,but Organic Light-Emitting Diode?OLED?is expected to become the next generation of mainstream display technology due to its excellent display quality.But whether it is LCD or OLED,the driving technology used is in the form of an active matrix,there is a key component which is inseparable-that is thin film transistor?TFT?.In so many TFT semiconductors,Metal oxide?MO?semiconductors are attracted wide attention because of their excellent performance,such as high mobility,low cost,and low process temperature.At present,MO-TFT has been used in large-size LCD TV products,but the application of small and medium-sized ultra-high-definition display products needs to solve the bias stability problem in the actual environment with light or heat.In view on this,we have incorporated an element into the ScInO semiconductor to form a quaternary semiconductor based on the original research about ScInO,in order to improve the bias thermal stability of the device.The first selected material is Mg,and MgScInO is used as the active layer of the TFT.Although the mobility of the fabricated TFT device is not high,the negative gate bias thermal stability is significantly improved.Based on the first-principles calculation,we found that Sc atoms tend to be aggregated,while Mg atoms tend to be segregated from each other;and oxygen vacancies?V_O?tend to be bound with Mg and form Mg-V_O pairs,requires an additional 0.1369 eV energy to excite oxygen vacancies,which is ascribed to the NBTS stability improvement for MgScInO TFT.The doping of Mg increases the stability of the TFT device,but the mobility is reduced,which is insufficient for high-resolution display technology.The reason for the decrease in mobility is mainly due to the large effective quality of MgO,and the overall effective mass increased after incorporation into ScInO.Therefore,we chose Cdt instead of Mg to dope into the ScInO semiconductor.Since CdO has the lowest electron effective mass in the transparent oxide material,it is expected that the incorporation of Cd can simultaneously improve the mobility and stability.Experiments show that the CdScInO TFT device prepared by Cd incorporation has higher mobility(14 cm² V^-11 s^-1)and relatively better stability.Even when the positive and negative bias stability is tested at 80°C,the turn-on voltage shift can be controlled within 0.2 V.The reason for this good stability may be that V_O is reduced due to the incorporation of Cd,and the energy level of V_O is closer to the conduction band,which is advantageous for the improvement of the stability of NBTS and PBTS.