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[manuscript.pdf](https://mdr.nims.go.jp/filesets/6c79da4e-2b46-463a-80f0-95c883159b58/download)

## Creator

[Jiangwei Liu](https://orcid.org/0000-0003-2580-7401), [Tokuyuki Teraji](https://orcid.org/0000-0002-7731-0547), [Bo Da](https://orcid.org/0000-0002-0785-8662), [Yasuo Koide](https://orcid.org/0000-0001-8321-9822)

## Rights

This is an original manuscript of an article published by Taylor & Francis in Functional Diamond on Jan. 19, 2025, available at: https://doi.org/10.1080/26941112.2025.2450513.[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[Boron-doped diamond MOSFETs operating at temperatures up to 400°C](https://mdr.nims.go.jp/datasets/70723897-08fb-4c73-8315-f8b4a36be0e6)

## Fulltext

1  Boron-doped diamond MOSFETs operating at temperatures up to 400 ℃ 1  2 Jiangwei Liu,1, a) Tokuyuki Teraji,1 Bo Da,2 and Yasuo Koide1 3  4 1Research Center for Electronic and Optical Materials, National Institute for Materials 5 Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan  6 2Research and Services Division of Materials Data and Integrated System, NIMS, 1-1 7 Namiki, Tsukuba, Ibaraki 305-0044, Japan  8  9 a) Author to whom correspondence should be addressed; electronic mail: 10 liu.jiangwei@nims.go.jp 11  12 Keywords: Single-crystal diamond; boron-doped; MOSFETs; high-temperature.  13  14  15  16  17  18  19  20  21  22  23  24 https://samurai.nims.go.jp/profiles?unit=wb000https://samurai.nims.go.jp/profiles?unit=kj000https://samurai.nims.go.jp/profiles?unit=kj0002  Abstract 1 The boron-doped diamond (B-diamond) metal-oxide-semiconductor field-effect 2 transistors (MOSFETs) are fabricated and characterized at operating temperatures up to 3 400 ℃. The SiO2 serves as the gate oxide insulator, while the Ti/Pt bilayer is employed 4 as the gate contact metal. As the operating temperature rises from room temperature 5 (RT) to 400 ℃, the absolute drain current for the B-diamond MOSFET increases from 6 3.9 μA mm-1 to 177.4 μA mm-1. Conversely, the on-resistance decreases significantly 7 from 1469.8 kΩ mm to 16.5 kΩ mm. The on/off ratio for the MOSFET at RT is 1.9 × 8 105, which increases to over 5.0 × 106 at temperatures exceeding 100 ℃. The threshold 9 voltage exhibits a decreasing trend, though it deviates from this trend at 300 ℃. The 10 subthreshold voltage and extrinsic transconductance maximum show increasing trends 11 from 113 mV dec-1 to 299 mV dec-1 and from 0.9 μS mm-1 to 23.1 μS mm-1, respectively. 12 The interfacial trapped charge density is found to be stable in the range of 8.0 × 1011 ~ 13 2.3 × 1012 eV-1 cm-2.  14  15  16  17  18  19  20  21  22  23  24 3  1. Introduction 1 Due to its exceptional intrinsic properties such as a wide bandgap energy, high 2 breakdown field, high carrier mobility, and excellent thermal conductivity, diamond has 3 been extensively studied for applications in high-power, high-frequency, and 4 high-temperature electronic devices [1, 2]. Hydrogen-terminated surface channels and 5 bulk-doped diamond channels are utilized in the production of electronic devices such 6 as metal-oxide-semiconductor field-effect transistors (MOSFETs) [3-12]. 7 Surface carbon-hydrogen bonds and negatively charged acceptors are two essential 8 requirements for hole accumulation in the p-type hydrogen-terminated diamond 9 (H-diamond) channel layer. The H-diamond-based MOSFETs exhibited outstanding 10 electrical characteristics, including a drain current maximum (ID,max) of 1.35 A mm-1 [3], 11 an extrinsic transconductance maximum (gm,max) of 206 mS mm-1 [3], a cut-off 12 frequency of 70 GHz [7], and a robust breakdown voltage of 3326 V [13]. However, the 13 limited thermal stability led to unsatisfied high-temperature performance [14] due to the 14 degradation of negatively charged acceptors on the H-diamond [15]. 15 In the case of bulk-doped diamond channels like the p-type boron-doped diamond 16 (B-diamond) and n-type phosphorus-doped diamond (P-diamond) channel layers, the 17 activation energies of boron (370 meV) and phosphorus (570 meV) dopants 18 significantly exceed the thermal energy (26 meV) available at room temperature (RT) 19 [1]. Consequently, their carrier densities are relatively low. The MOSFETs on the 20 B-diamond and P-diamond exhibited low ID,max and gm,max values [9, 10, 16]. 21 Nevertheless, as there is no surface thermal sensitivity issue with bulk-doped diamond 22 channels, it is anticipated that the B-diamond and P-diamond MOSFETs can perform 23 effectively at high temperatures. 24 4  Previously, we have fabricated the B-diamond MOSFETs and examined their 1 electrical properties [11, 12, 17]. At RT, the B-diamond MOSFET displayed an ID,max of 2 -1.2 mA mm-1 and a gm,max of 29.0 μS mm-1. Impressively, even at an operating 3 temperature of 300 ℃, the B-diamond MOSFET continued to perform well, showing an 4 ID,max of -10.9 mA mm-1 and a gm,max of 215.7 μS mm-1 [17]. However, while operating 5 temperature up to 400 ℃, significant degradation in the performance of the B-diamond 6 MOSFETs was observed. This degradation is likely attributed to that the in-situ 7 high-temperature annealing deteriorates the qualities of the Al2O3 gate oxide insulator 8 and the Ti/Au bilayer gate contact metal. 9 To further improve the performance of B-diamond MOSFETs at high operating 10 temperatures, we have employed SiO2 gate insulator and Ti/Pt bilayer gate contact metal 11 in the fabrication process. We have conducted a thorough examination and discussion of 12 their electrical characteristics at operating temperatures of RT, 100 ℃, 200 ℃, 300 ℃, 13 and 400 ℃. 14 2. Experimental 15 The fabrication process for the B-diamond MOSFETs has been reported previously 16 [17]. Initially, the Ib-type (100) diamond substrate underwent cleaning by immersion in 17 a solution of H2SO4 + HNO3 at 300 ℃ for 3 hours. Subsequently, the B-diamond 18 epitaxial layer was grown using a microwave plasma-assisted chemical vapor 19 deposition system with source gases of H2 and CH4 [18]. Boron was sourced from the 20 residual boron in the chamber of the prior B-diamond growth. Secondary ion mass 21 spectrometry measurement indicated that the B-diamond epitaxial layer had a thickness 22 of 825 nm with a boron atom concentration of approximately 4 × 1015 cm-3. 23 The B-diamond epitaxial layer underwent treatment in the acid solution (H2SO4 + 24 5  HNO3) once more, converting its hydrogen surface to oxygen. Source and drain 1 electrodes, comprised of a Ti/Au bilayer (10/150 nm), were evaporated onto the 2 B-diamond using an electron-gun evaporation system. The chamber pressure for 3 evaporating the Ti/Au bilayer was around 10-6 Pa, with evaporation rates for Ti and Au 4 of 1.0 and 2.0 Å s-1, respectively. Annealing at 550 ℃ for 20 minutes in an Ar 5 atmosphere facilitated the formation of Ohmic contacts using a rapid thermal annealing 6 system.  7 A SiO2 gate oxide, approximately 11 nm thick, was deposited through an atomic 8 layer deposition system at 300 ℃ using bis(diethylamino)silane and ozone precursors. 9 The pulse times for these precursors were 200 msec and 150 msec, with purge times of 10 4 s and 6 s, respectively. The carrier gas of N2 flowed at a rate of 100 sccm. A Ti/Pt 11 (10/100 nm) bilayer served as the gate electrode formed using the electron-gun 12 evaporation system. Evaporation rates for Ti and Pt were set at 1.0 and 0.5 Å/s, 13 respectively. Following this, a 7.6 nm-thick SiO2 film was redeposited to cover the 14 entire sample surface. This additional SiO2 layer served to protect the B-diamond 15 MOSFETs from environmental effects and the edge leakage of the electrodes, thereby 16 enhancing their reliability and performance. Electrode access windows were created by 17 etching the SiO2 film in the HF acid solution. The electrical characteristics for the 18 B-diamond MOSFETs were obtained using a Grail 10-5-LV-HTV prober system across 19 temperatures ranging from RT to 400 ℃. 20 3. Results and discussion 21 Figures 1(a) and 1(b) show microscope image and schematic diagram of the 22 B-diamond MOSFET, respectively. The diameter for the drain electrode is 301.6 μm. 23 The gate width (WG) can be computed as 947.0 μm. The gate length is 4.8 μm. The 24 6  interspatial distances for the gate-to-source and gate-to-drain electrodes are both 5.0 1 μm.  2 Figure 2(a) shows the ID as a function of drain voltage (VD) for the B-diamond 3 MOSFET operating at RT. The VGS varies from -2.0 to 33.0 V in steps of +1.0 V. The 4 B-diamond MOSFET shows obvious saturation regions and operates with a p-type 5 characteristic. The absolute ID,max for the B-diamond MOSFET operating at RT is 3.9 μA 6 mm-1, which is lower than that of the previous reported value of 1.2 mA mm-1 [17]. It 7 was confirmed that the low doping level and thin channel layer thickness for the 8 B-diamond epitaxial layer would lead to the decrease of ID,max [19]. These are the 9 reasons for the lower ID,max here. Based on the linear region for the ID-VD characteristic 10 at the VGS of -2.0 V, on-resistance (RON) normalized by the WG can be deduced to be 11 1469.8 kΩ mm.  12 The ID as a function of gate-to-source voltage (VGS) for the B-diamond MOSFET 13 operating at RT is shown in Fig. 2(b). The VD is kept at -10.0 V. The on/off ratio is 14 determined at the VGS of -2.0/15.0 V to be 1.9 × 105. Through linear extrapolation, 15 threshold voltage (VTH) is found to be 8.3 V. Subthreshold voltage (SS) value for the 16 MOSFET operating at RT is determined to be 113 mV/dec. Then, interfacial trapped 17 charge density (Dit) of the SiO2/B-diamond at RT can be calculated using the following 18 equation (1) [20]. 19 ln(10) 1 itOXqDkTSSq C = +   ,                         (1) 20 where k, T, q, and COX are Boltzmann’s constant (8.62×10-5 eV K-1), operating 21 temperature, elementary charge (1.6 × 10-19 C), and SiO2 oxide capacitance (0.314 22 μF/cm2) which is calculated based on its thickness (11 nm) and dielectric constant (3.9), 23 7  respectively. The Dit for the B-diamond MOSFET operating at RT is computed as 1.8 × 1 1012 eV-1 cm-2, which is better than that of the Al2O3/B-diamond interface of 7.2 × 1012 2 eV-1 cm-2 [17]. Since the oxygen vacancies on the surface of the B-diamond and the 3 interfacial quality of the oxide/B-diamond can be modified by the oxygen precursors 4 during the atomic layer deposition [12], opting for a higher deposition temperature of 5 300 ℃ for SiO2 compared to the 200 ℃ for Al2O3 would possibly enhance these 6 modifications, leading to the better interfacial quality for SiO2/B-diamond and the low 7 Dit. 8 Figure 3(a) displays the ID-VD characteristics for the B-diamond MOSFETs 9 operating from 100 ℃ to 400 ℃ with the VGS maintained at -2.0 V. Even at an elevated 10 operating temperature of 400 ℃, the B-diamond MOSFET continues to operate well. 11 Therefore, the transition of gate oxide insulator from Al2O3 to SiO2 and gate cover metal 12 from Ti/Au to Ti/Pt have enhanced the high-temperature properties for the B-diamond 13 MOSFETs. The ID,max values for the B-diamond operating at 100, 200, 300, and 400 ℃ 14 are -33.3, -57.8, -78.1, and -177.4 μA mm-1, respectively. Correspondingly, their RON 15 values are determined to be 191.8, 106.6, 75.5, and 16.5 kΩ mm, respectively. Fig. 3(b) 16 illustrates the ID-VGS characteristics for the B-diamond MOSFETs operating from 17 100 ℃ to 400 ℃. The on/off ratios of them exceed 5 × 106, surpassing the MOSFET 18 operating at RT. With the fluctuation in operating temperature, the VTH value undergoes 19 significant shifts, indicating the variations of charges and hole densities for the 20 B-diamond MOSFETs. Further details regarding the on/off ratio, VTH value, SS value, 21 and Dit value will be elaborated in subsequent discussions. 22 Figures 4(a) and 4(b) present summaries of the ID and RON as functions of 23 operating temperature for the B-diamond MOSFETs, respectively. As the operating 24 8  temperature increases, the absolute ID,max increases from 3.9 to 177.4 μA mm-1. The 1 ID,max operating at 400 ℃ is approximately 45 times greater than that operating at RT. 2 Conversely, the RON experiences a significant decrease from 1469.8 kΩ mm at RT to 3 16.5 kΩ mm at 400 ℃. The activation of boron dopants at higher operating 4 temperatures enhances the carrier density and augments the properties of the B-diamond 5 MOSFETs. 6 Figures 5(a), 5(b), 5(c), and 5(d) summarize the on/off ratio, VTH, SS value, and Dit as 7 functions of operating temperature for the B-diamond MOSFETs, respectively. The 8 on/off ratios for the B-diamond MOSFET exceeding 100 ℃ are more than one order 9 higher than that at RT, indicating efficient control over the flow of current at higher 10 operating temperatures. The VTH exhibits a decreasing trend, though it deviated from 11 this trend at 300 ℃, possibly due to the variations of charges in the SiO2 or at the 12 Pt/Ti/SiO2 interfaces. With the increase in operating temperature, the SS value rises 13 from 113 mV/dec at RT to 299 mV/dec at 400 ℃. Based on the equation (1), the Dit can 14 be computed to be stable in the range of 8.0 × 1011 ~ 2.3 × 1012 eV-1 cm-2. Consequently, 15 the elevated operating temperature does not degrade the interfacial quality for the 16 SiO2/B-diamond.  17 Figures 6(a) and 6(b) depict the gm -VGS characteristics and gm,max as a function of 18 operating temperature for the B-diamond MOSFETs, respectively. At RT, the gm,max is 19 0.9 μS mm-1, which significantly increases to be more than 25 times, reaching 23.1 μS 20 mm-1 at 400 ℃. Table 1 summarizes the electrical properties of the B-diamond 21 MOSFETs operating across the temperatures ranging from RT to 400 ℃. With the 22 increase of operating temperature, the ID,max, on/off ratio, and gm,max demonstrate 23 improvements, showcasing enhanced performance characteristics of the B-diamond 24 9  MOSFETs as the temperature rises. 1 4. Conclusions 2 To enhance the performance of the B-diamond MOSFETs operating at temperatures 3 up to 400 ℃, the utilization of SiO2 gate insulator and Ti/Pt bilayer gate contact metal 4 was adopted in their fabrication. A comprehensive investigation and discussion of their 5 electrical properties at operating temperatures ranging from RT, 100 ℃, 200 ℃, 300 ℃, 6 to 400 ℃ were conducted. As the operating temperature increased, the absolute ID,max 7 surged from 3.9 μA mm-1 to approximately 45 times the value, reaching 177.4 μA mm-1. 8 The on/off ratios for the B-diamond MOSFETs at temperatures surpassing 100 ℃ 9 exceeded one order higher than that at RT. Furthermore, the gm,max, initially at 0.9 μS 10 mm-1 at RT, increased significantly to more than 25 times of 23.1 μS mm-1 at 400 ℃. 11 This study is of importance for understanding the behavior and performance of 12 B-diamond MOSFETs operating at high temperatures such as 400 ℃. 13  14 Funding 15 This work was supported by the JSPS KAKENHI Projects (JP23K03966, 20H05661, 16 and JP20H00313), MEXT Q-LEAP (JPMXS0118068379), JST Moonshot R&D 17 (JPMJMS2062), MIC R&D for construction of a global quantum cryptography 18 network (JPMI00316), and ARIM (23WS0311 and 23NM5006) of the Ministry of 19 Education, Culture, Sports, Science and Technology, Japan. The authors would like to 20 thank the technical supports from Prof. Sasaki and Prof. Sekiguchi at Research 21 Organization for Nano & Life Innovation in Waseda University. 22  23  24 10  Disclosure Statement 1 No potential conflict of interest was reported by the authors. 2  3 Table 1. Summary of electrical properties of the B-diamond MOSFETs operating across 4 the temperatures range from RT to 400 ℃. 5  RT 100 ℃ 200 ℃ 300 ℃ 400 ℃ ID,max (μA mm-1) -3.9 -33.3 -57.8 -78.1 -177.4 RON (kΩ mm) 1469.8 191.8 106.6 75.5 16.5 On/off 1.9 × 105 6.4 × 106 2.2 × 107 5.3 × 106 5.5 × 106 VTH (V) 8.3 7.3 6.8 11.5 4.1 SS (mV dec-1) 113 153 139 170 299 Dit (eV-1 cm-2) 1.8 × 1012 1.8 × 1012 8.0 × 1011 8.5 × 1011 2.3 × 1012 gm,max (μS mm-1) 0.9 6.9 11.5 21.0 23.1  6  7  8  9  10  11  12  13  14  15  16  17  18  19 11   1  2  3  4 References 5 [1] Wort CJH, Balmer RS. Diamond as an electronic material. Mater. Today. 2008; 6 11(1-2): 22-28. 7 [2] Baliga BJ. Power semiconductor device figure of merit for high-frequency 8 applications. IEEE Electron Dev. Lett. 1989; 10(10): 455-457. 9 [3] Hirama, K, Sato H, Harada Y, et al. Diamond field-effect transistors with 1.3 A/mm 10 drain current density by Al2O3 passivation layer. Jpn. J. Appl. Phys. 2012; 51(9R): 11 090112. 12 [4] Kawarada H, Yamada T, Xu D, et al. Diamond MOSFETs using 2D hole gas with 13 1700 V breakdown voltage. Proc. 28th Int. Symp. Power Semiconductor Devices ICs. 14 2016; 483-486. 15 [5] Liu J, Ohsato H, Liao M, et al. Logic circuits with hydrogenated diamond 16 field-effect transistors. IEEE Electron Dev. Lett. 2017; 38(7): 922-925. 17 [6] Ren Z, Zhang J, Zhang J, et al. Diamond field effect transistors with MoO3 gate 18 dielectric. IEEE Electron Dev. Lett. 2017; 34(6): 786-789. 19 [7] Yu X, Zhou J, Qi C, et al. A high frequency hydrogen-terminated diamond MISFET 20 with fT/fmax of 70/80 GHz. IEEE Electron Dev. Lett. 2019; 39(9): 1373-1376. 21 [8] Wang W, Wang Y, Zhang M, et al. An enhancement-mode hydrogen-terminated 22 diamond field-effect transistor with lanthanum hexaboride gate material. IEEE Electron 23 Dev. Lett. 2020; 41(4): 585-588. 24 12  [9] Pham TT, Pernot J, Perez G, et al. Deep-depletion mode boron-doped 1 monocrystalline diamond metal oxide semiconductor field effect transistor. IEEE 2 Electron Dev. Lett. 2017; 38(11):1571-1574. 3 [10] Pham TT, Rouger N, Masante C, et al. Deep depletion concept for diamond 4 MOSFET. Appl. Phys. Lett. 2017; 111(17): 173503. 5 [11] Liu J, Teraji T, Da B, et al. Boron-doped diamond MOSFETs with high output 6 current and extrinsic transconductance. IEEE Tran. Electron Dev. 2021; 68(8): 7 3963-3967. 8 [12] Liu J, Teraji T, Da B, et al. Electrical properties of boron-doped diamond 9 MOSFETs with ozone precursor for Al2O3 deposition. IEEE Tran. Electron Dev. 2023; 10 70(5): 2199-2203. 11 [13] Saha N, Kim S, Oishi T, et al. 3326 V Modulation-Doped Diamond MOSFETs. 12 IEEE Electron Dev. Lett. 2022; 43(8): 1303-1306. 13 [14] Liu J, Oosato H, Da B, et al. Operations of hydrogenated diamond 14 metal-oxide-semiconductor field-effect transistors after annealing at 500 ℃. J. Phys. D: 15 Appl. Phys. 2019; 52(31): 315104. 16 [15] Liu J, Liao M, Imura M, et al. Control of normally on/off characteristics in 17 hydrogenated diamond metal-insulator-semiconductor field-effect transistors. J. Appl. 18 Phys. 2015; 118(11): 115704. 19 [16] Matsumoto T, Kato H, Oyama K, et al. Inversion channel diamond 20 metal-oxide-semiconductor field-effect transistor with normally off characteristics. Sci. 21 Rep. 2016; 6: 31585. 22 13  [17] Liu J, Teraji T, Da B, et al. Electrical property improvement for boron-doped 1 diamond metal-oxide-semiconductor field-effect transistors. Appl. Phys. Lett. 2024; 2 124(7): 072103. 3 [18] Teraji T, Yamamoto T, Watanabe K, et al. Homoepitaxial diamond film growth: 4 High purity, high crystalline quality, isotopic enrichment, and single-color center 5 formation. Phys. Stat. Solidi A. 2015; 212(11): 2365-2384. 6 [19] Liu J, Oosato H, Da B, et al. Suppression of high threshold voltage for 7 boron-doped diamond MOSFETs. IEEE Trans. Electron Dev. 2024; 71(3):1764-1768. 8 [20] Sze SM. Physics of semiconductor devices. New York: Wiley: 1981. 9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24 14   1  2  3 Figure captions 4  5 Figure 1. (a) Microscope image and (b) schematic diagram of the B-diamond MOSFET, 6 respectively. 7  8 Figure 2. (a) ID-VD and (b) ID-VGS characteristics for the B-diamond MOSFET operating 9 at RT, respectively. The VGS in Fig. 2 (a) is changed from -2.0 V to 33.0 V in steps of 10 +1.0 V. The VD in Fig. 2(b) is kept at -10.0 V. 11  12 Figure 3. (a) ID-VD and (b) ID-VGS characteristics for the B-diamond MOSFETs 13 operating from 100 ℃ to 400 ℃. The VGS in Fig. 3(a) is kept at -2.0 V. The VD in Fig. 14 3(b) is kept at -10.0 V. 15  16 Figure 4. (a) ID and (b) RON as functions of operating temperature for the B-diamond 17 MOSFETs, respectively. 18  19 Figure 5. (a) On/off ratio, (b) VTH, (c) SS value, and (d) Dit as functions of operating 20 temperature for the B-diamond MOSFETs, respectively. 21  22 Figure 6. (a) gm -VGS characteristics and (b) gm,max as a function of operating temperature 23 for the B-diamond MOSFETs, respectively. 24 15   1  2  3 Diamond (100)Ti/Au4.8 μm5.0 μm 5.0 μmTi/AuTi/PtBoron-doped diamondSiO2 SiO2100 μm(b)(a)GateSourceDrain 4  5  6 Liu et al., Figure 1 7  8  9  10  11  12  13  14  15  16  17  18  19 16   1  2  3 0 −2 −4 −6 −8 −100−1−2−3−4−530 25 20 15 10 5 0 −510−810−610−410−2100102I D  (μA/mm)VD (V)VGS: –2.0 ~ 33.0 VStep: +1.0 V(a) (b)I D (μA/mm)VGS (V)VTH = 8.3 VOn/off:  1.9×105SS: 113 mV/decVD = –10.0 VVGS = –2.0  VStep 4  5  6 Liu et al., Figure 2 7  8  9  10  11  12  13  14  15  16  17  18 17   1  2 0 −2 −4 −6 −8 −100−50−100−150−200 30 25 20 15 10 5 0 −510−810−610−410−2100102     I D  (μA/mm)VD (V)(a)100 ℃200 ℃300 ℃400 ℃100 ℃200 ℃300 ℃400 ℃VGS = –2.0  V(b)I D (μA/mm)VGS (V)VD = –10.0 V 3  4  5 Liu et al., Figure 3 6  7  8  9  10  11  12  13  14  15  16  17  18 18   1  2 0−50−100−150−200101102103I D  (μA/mm)100 200 300 400(a) (b)RTTemperature (℃)100 200 300 400RTTemperature (℃)RON  (kΩmm) 3  4  5 Liu et al., Figure 4 6  7  8  9  10  11  12  13  14  15  16  17 19   1  2 On/off 100 200 300 400(a) (b)RTTemperature (℃)100 200 300 400RTTemperature (℃)VTH  (V)1051061071082468101250100150200250300350101110121013SS(mV/dec.)100 200 300 400(c) (d)RTTemperature (℃)100 200 300 400RTTemperature (℃)Dit(eV‒1cm‒2) 3  4  5 Liu et al., Figure 5 6  7  8  9  10  11 20   1  2 16 14 12 10 8 6 4 2 0 −20510152025     100 ℃200 ℃300 ℃400 ℃RT0510152025gm,max(μS/mm)100 200 300 400(b)RTTemperature (℃)gm (μS/mm)VGS (V)(a) 3  4  5 Liu et al., Figure 6 6  7