Amorphous ZnAlSnO thin-film transistors by a combustion
solution process for future displays
Qingjun Jiang,1 Lisha Feng,1 Chuanjia Wu,1 Rujie Sun,1 Xifeng Li,2 Bin Lu,1 Zhizhen
Ye,1 and Jianguo Lu1, a)
1
State Key Laboratory of Silicon Materials, School of Materials Science and
Engineering, Zhejiang University, Hangzhou 310027, China
2
Key Laboratory of Advanced Display and System Application, Ministry of Education,
Shanghai University, Shanghai 200072, China
a)
Electronic mail: lujianguo@zju.edu.cn
Table S1 SOII/SOall values of O 1s XPS spectra for a-ZATO (0, 0.25, 0.5, 1.0 and 2.0)
films, where SOI, SOII, SOIII and SOall are the area of OI, OII, OIII and the OI+OII+OIII,
respectively.
Samples
SOI
ZATO
(0)
0.79
ZATO
(0.25)
1.22
ZATO
(0.5)
1.24
ZATO
(1.0)
1.33
ZATO
(2.0)
1.32
SOII
SOIII
SOII/ SOall
0.27
0.10
23.44%
0.35
0.13
20.71%
0.32
0.10
19.23%
0.30
0.11
17.24%
0.32
0.12
20.98%
Table S2 Vth changes of the ZATO (0) TFT and ZATO (0.5) TFT under PBS and NBS
for various time (0, 10, 100, 1000 and 5000 s).
Vth (V)
PBS-ZATO (0)
NBS-ZATO (0)
PBS-ZATO (0.5)
NBS-ZATO (0.5)
0s
-5.29
0.91
-3.55
-0.10
10 s
-3.85
-0.64
-2.41
-1.96
100 s
-3.02
-2.20
-1.81
-2.26
1000 s
-0.30
-5.46
-0.25
-2.74
5000 s
2.56
-12.29
2.77
-5.89
ΔVth
7.85
-13.20
6.32
-5.79
Table S3 SS values of the ZATO (0) TFT and ZATO (0.5) TFT under PBS and NBS
for various time (0, 10, 100, 1000 and 5000 s).
SS (V/decade)
PBS-ZATO (0)
NBS-ZATO (0)
PBS-ZATO (0.5)
NBS-ZATO (0.5)
0s
0.84
0.61
0.89
0.83
10 s
0.89
0.52
0.93
0.80
100 s
0.80
0.540
0.80
0.84
1000 s
0.62
0.59
0.87
0.88
5000 s
0.65
0.68
0.78
0.90
Fig. S1 TGA and DTA of ZATO (0, 0.25, 0.5, 1.0 and 2.0) precursors in the
temperature range from RT to 400 ºC.
TGA and DTA were examined by TA Q600 under a N2 atmosphere at 5 ºC min-1 in
the temperature range of RT-400 ºC. Fig. S1 gives the TGA and DTA of ZATO (0,
0.25, 0.5, 1.0 and 2.0) precursors with the temperature range from RT to 400 ºC. The
decomposition temperature is about 70-87 ºC, corresponding to the onset of the
combustion process, and corresponding to a very sharp exotherm in the DTA. The
decomposition temperature is evidently lower than those commonly reported such as
190 ºC for indium-zinc oxide (IZO) precursors, (J. Am. Chem. Soc. 135, 10729
(2013)) which enables the possibility of flexible devices below 90 ºC theoretically.
Here, to improve device performances, a low-temperature annealing step was carried
out at 300 ºC, which is also lower than those commonly reported in previous
literatures for the combustion process and still appropriate for some flexible substrates
like polyimide.
Fig. S2 (a) Al 2p3/2, (b) Zn 2p3/2, (c) Sn 3d5/2 XPS spectra of the a-ZATO films with
various Al contents.
Fig. S2 (a)–2(c) depict the Al 2p3/2, Zn 2p3/2, and Sn 3d5/2 XPS spectra of ZATO
films. All the binding energy data are calibrated by taking C 1s reference at 284.8 eV
to compensate for any charge-induced shifts. The Al 2p3/2, Zn 2p3/2, and Sn 3d5/2 peaks
are centred at around 73.90, 1022.2, and 486.49 eV, respectively, indicating the
characteristic values of fully oxides. (Appl. Phys. Lett. 97, 233502 (2010))
In detailed analysis, the Al 2p3/2 peaks exhibit a gradual increase in intensity as the
Al content increases from 0 to 2.0, while there is almost no change in position. The
Zn 2p3/2 peak shifts to a low binding energy with increasing Al content from 0 to 1.0.
Previous reports have demonstrated that the shift to low binding energy for metal ions
implies the decrease of oxygen vacancies (VO) in an oxygen system. Thus, this
low-binding-energy shift indicates the decrease of VO in the ZATO matrix, which may
be due to the oxygen attraction of low-SEP Al ions (-1.66 V). In the ZATO system,
Al can play a much crucial role in suppressing the formation of VO. (Appl. Phys. Lett.
2013, 103, 082109). As the Al content is further up to 2.0, the Zn 2p3/2 peak begins to
shift to a high binding energy, which suggesting the increase of VO in the ZATO
matrix. The Sn 3d5/2 peak of 486.49 eV comes from the Sn4+ bonding, implying that
Sn atoms are fully oxidized to the Sn4+state in the system. The shift tendency of Sn
3d5/2 peak with Al contents is similar to that of Zn 2p3/2 peak, which further confirms
our above analysis.
Fig. S3 The output characteristics (IDS-VDS) of a-ZATO (0, 0.25, 1.0 and 2.0) based
TFT devices.
Fig. S3 plots the representative output characteristics (IDS-VDS) of a-ZATO (0,
0.25, 1.0 and 2.0) based TFT devices. The TFT device has a good ohmic contact at
the Al/channel interface because no current crowding at low VDS is observed. A clear
pinch-off and current saturation are observed. The saturation current of IDS markedly
increases as the positive gate bias (VGS) increases, indicating the TFT device operates
in an enhanced mode with an n-type channel.