Effects Of Fabrication Technology On The Performances Of Amorphous InSnZnO Thin-film Transistors

TFTs on flexible substrates is a key component to realize flexible electronics, whichwill be indispensable in near future ubiquitous network technology, as they can be used todevelop advanced optoelectronic devices. Thin film transistors (TFTs) using transparentamorphous semiconductors are considered as an attractive alternative to conventionalsilicon based TFTs. Next generation flat plane displays using amorphous oxidesemiconductors (AOSs) due to their wide optical band gap (3.5eV), good electricalconductivity (103Ωcm-1), and high optical transparency (80%) have been widely used inTFTs, which is the state of art technology attracting huge attention in semiconductorindustries. Especially TFTs with amorphous indium tin zinc oxide (a-ITZO) as the activelayers attract the more attention. At present, sputtering is the main fabrication methods ofTFTs devices. The change of the thin films deposition process parameters has a significantinfluence on the performances of TFTs devices.The parameters on TFTs device performances optimization has been studied andanalyzed in detail and systematically, which include the device structures, the compositionof active layer, the contact resistances between source/drain and gate dielectricmaterials.a-ITZO TFTs are made based on Si substrates by DC magnetron sputter methodwith various working powers and O2ratio. It is concluded that sputtering powers andoxygen ratios by changing the interface trap density (Nt) between channel layer andinsulating layer and carrier concentration (Nd) within the channel mainly, which affect TFTsdevice performances. i) At the power of80W, TFTs exhibiting excellent electricalperformances, the subthreshold slope (S.S) of0.16V/dec, the on-voltage (VON) of-3.60V,highest on-off current ratio (ION/IOFF) of7.77×108. Moreover, the devices also showed better stability than others against the applied negative bias stress. ii) The samples with oxygenratios of30%with lowest interface state density (Nt) has a high field-effect mobility (μFE)of43.88cm2V-1s-1, a high on/off current ratio (ION/IOFF) of1.15×109and a lowsubthreshold swing (S.S) of0.18V/dec. The feasibility of the influences of preparationprocesses on the performance of a-ITZO TFTs is verified by experiments. To provide abasis for the reasonable preparation conditions in the future and to make the devices showbetter performances.