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

doi:10.15541/jim20150613

Abstract

Abstract:

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 I_on/I_off 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.

Key words: double channel layers, nitrogen doped, thermal stability, thin film transistors

CLC Number:

TN321

WANG Nai-Qian, ZHANG Qun, SHIEH Han-Ping. Influence of Double Channel Layers on the Performance of Nitrogen Doped Indium-zinc-oxide Thin Film Transistors[J]. Journal of Inorganic Materials, 2016, 31(7): 745-750.

Figures/Tables 7

Fig. 1 Schematic structure of the TFTs with various channel layers (a) a-IZO; (b) a-IZO/IZON; (c) a-IZON/IZO; (d) a-IZON

Fig. 2 XRD patterns for different channel layers

Fig. 3 Transmission curves of different channel layers

Fig. 4 Transfer characteristics (ID-VG) curves of the TFTs with different structures of channel layers

Table 1 Charateristics of the TFTs with different channel layers

Channel layers	μ_FE/ (cm²·V^-1·s^-1)	V_th /V	S.S/ V∙dec^-1	I_on/off
a-IZO	27.98	-3.0	0.5	3.1×10⁸
a-IZO/IZON	23.26	-2.5	0.5	1.6×10⁸
a-IZON/IZO	21.02	-1.5	0.5	8.3×10⁷
a-IZON	14.50	0.5	0.8	1.2×10⁸

Fig. 5 Transfer characteristics (ID-VG) curves of the TFTs tested at different temperatures (a) a-IZO; (b) a-IZO/IZON; (c) a-IZON/IZO; (d) a-IZON

Fig. 6 Temperature dependency of ∆Vth for TFTs with different channel layers

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