Gallium–Indium–Zinc-Oxide-Based Thin-Film Transistors: Influence of the Source/Drain Material

Abstract

Abstract-During the last years, oxide semiconductors have shown that they will have a key role in the future of electronics. In fact, several research groups have already presented working devices with remarkable electrical and optical properties based on these materials, mainly thin-film transistors (TFTs). Most of these TFTs use indium-tin oxide (ITO) as the material for source/drain electrodes. This paper focuses on the investigation of different materials to replace ITO in inverted-staggered TFTs based on gallium-indium-zinc oxide (GIZO) semiconductor. The analyzed electrode materials were indium-zinc oxide, Ti, Al, Mo, and Ti/Au, with each of these materials used in two different kinds of devices: one was annealed after GIZO channel deposition but prior to source/drain deposition, and the other was annealed at the end of device production. The results show an improvement on the electrical properties when the annealing is performed at the end (for instance, with Ti/Au electrodes, mobility rises from 19 to 25 cm 2 /V · s, and turn-on voltage drops from 4 to 2 V). Using time-of-flight secondary ion mass spectrometry (TOF-SIMS), we could confirm that some diffusion exists in the source/drain electrodes/semiconductor interface, which is in close agreement with the obtained electrical properties. In addition to TOF-SIMS results for relevant elements, electrical characterization is presented for each kind of device, including the extraction of source/ drain series resistances and TFT intrinsic parameters, such as µ i (intrinsic mobility) and V Ti (intrinsic threshold voltage).

Oxide semiconductors: Order within the disorder

“…TFT is comparable and in some cases superior to those of a-GIZO TFTs that have been proved to build up quite large area active matrix with excellent performances, when compared with today's technology [33,78]. This is a clear advantage since the replacement of In by Sn in the Ga-Zn-O system, is quite important due to the limited availability of In.…”

“…Nowadays these active oxides are key components in a wide range of device applications like sensors [29] and thin-film transistors (TFTs), where it has been demonstrated that they can present high electronic performance even when disordered ionic oxides are used [30][31][32][33][34][35][36]. Concerning p-type oxide semiconductors, this activity has been also pursued in the last years [37][38][39][40][41][42][43][44][45].…”

Comparison of Stability on the Nano-crystalline Embedded InGaZnO and Amorphous InGaZnO Oxide Thin-film Transistors

“…최근에 이러한 한계를 극복하고자 소자 특성 및 신 뢰성 향상에 대한 연구가 활발히 진행되고 있다 [6][7][8][9][10][11][12]. 다양한 물질의 조합을 통한 특성 향상뿐만 아 니라 [6,7] [ ] …”

Improvement on the Stability of Amorphous Indium Gallium Zinc Oxide Thin Film Transistors Using Amorphous Oxide Multilayer Source/Drain Electrodes

“…Particularly, amorphous indium zinc oxide (a-IZO) was used for an S/D electrode of ZnO TTFTs due to its high transparency and lower resistivity. Although there was a lot of research regarding S/D electrodes of ZnO based TFTs, such as the transparency, resistivity, and contact problem with the channel layer, the relation between the stability of ZnO based TFTs under the various stress and S/D electrodes is still unknown [5][6][7][8].…”