双沟道层对氮掺杂非晶氧化铟锌薄膜晶体管的影响

Influence of Double Channel Layers on the Performance of Nitrogen Doped Indium-zinc-oxide Thin Film Transistors

采用射频磁控溅射法,在热氧化p型硅基片上制备了双沟道层非晶氧化铟锌(a-IZO)和氮掺杂氧化铟锌(a-IZON)薄膜晶体管(TFTs),并研究了双沟道层对器件电学性能和温度稳定性的影响。研究发现,a-IZO/IZON双沟道层TFTs具有较高的场效应迁移率,为23.26 cm2/(V?s),并且其阈值电压相较于单层a-IZO-TFTs正向偏移。这是由于氮掺杂可以减少沟道层中的氧空位,抑制载流子浓度,使器件具有更好的阈值电压。而a-IZO层避免了由于氮掺杂导致的场效应迁移率和开态电流的下降,提升了器件的电流开关比。从298 K至423 K的器件转移特性曲线中发现,双沟道层器件相较于单沟道层器件的温度稳定性更佳,这可归因于a-IZON层的保护作用。氮掺杂可以减少氧在背沟道层表面的吸收/解吸反应,改善器件的稳定性。

The nitrogen-doped amorphous indium-zinc-oxide thin film transistors with double channel layers（a-IZO/IZON-TFTs） were fabricated by RF magnetron sputtering of IZO target on the thermal oxidized p-type Si substrate.Influence of the double channel layers on the electrical performance and thermal stability of the devices were investigated.It is found that a-IZO/IZON-TFTs have high field effect mobility of 23.26 cm2/（V？s） and more positively shifted threshold voltage than that of a-IZO-TFTs.This is ascribed to the doped nitrogen which can help reduce oxygen vacancy in the channel layer,suppress carrier concentration and make the devices have a better threshold voltage.Meanwhile,employing a-IZO thin film can avoid the sharp drop of field effect mobility and drain on current caused by nitrogen doping on a-IZON layer,leading to promoting Ion/Ioff ratio effectively.Besides,according to the transfer characteristics measured at temperatures from 298 K to 423 K,devices with a-IZO/IZON double layers have superior performance and thermal stability to TFTs of single channel layer,which can be ascribed to the protective effect of a-IZON thin film on the channel layers.The doped nitrogen can reduce the adsorption/desorption reaction of oxygen molecules on the back channel layer,leading to a significant improvement on thermal stability of the devices.