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[J. Liu](https://orcid.org/0000-0003-2580-7401), [T. Teraji](https://orcid.org/0000-0002-7731-0547)

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This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Liu, T. Teraji; Impact of doping profile on electrical performance of boron-doped diamond metal–oxide–semiconductor field-effect transistors. J. Appl. Phys. 14 July 2026; 140 (2): 024504 and may be found at https://doi.org/10.1063/5.0318837.[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

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[Impact of doping profile on electrical performance of boron-doped diamond metal–oxide–semiconductor field-effect transistors](https://mdr.nims.go.jp/datasets/f1513885-572e-4e6a-8b6d-17b65af26c65)

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Impact of doping profile on electrical performance of boron-doped diamond MOSFETsJ. Liu,1, a) and T. Teraji1 1Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan a) Author to whom correspondence should be addressed; electronic mail: liu.jiangwei@nims.go.jpAbstractElectrical characteristics of boron-doped diamond (B-diamond) metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated on an epitaxial layer with a thickness (tboron) of 1514 nm and a boron doping concentration (Nboron) level of 1017 cm-3 are investigated. For the as-fabricated B-diamond MOSFET operating at room temperature (298 K), the maximum absolute drain current (|ID,max|) is 4.7 mA/mm. At elevated temperatures of 573 K and 673 K, the |ID,max| values increase to 76.9 mA/mm and 109.2 mA/mm, respectively. The threshold voltage (VTH) values for B-diamond MOSFETs operating at 298 K, 573 K, and 673 K are 320.2 ±5.0 V, 1143.2 ±20.0 V, and 895.1 ±20.0 V, respectively. Post-annealing at 773 K for 30 minutes, the |ID,max| and VTH measured at 298 K improve to 6.0 mA/mm and 258.7 ±5.0 V, respectively. Capacitance–voltage measurements indicate that the annealing process improves the dielectric property of the Al2O3 insulator and reduces the fixed and trapped charge densities in the Al2O3/B-diamond MOS capacitor. Impact of the doping profile on the electrical performance of B-diamond FETs is summarized. At a constant Nboron level, both |ID,max| and VTH increase with increasing tboron. On the other hand, at a similar tboron, these parameters increase with higher Nboron.I. INTRODUCTIONWide bandgap semiconductors such as silicon carbide, gallium nitride, and diamond exhibit superior efficiency and thermal performance compared to conventional silicon, leading to the development of smaller, lighter, and more energy-efficient systems.1-3 Among these materials, diamond stands out due to its exceptional physical properties, including an ultra-wide bandgap of 5.5 eV, outstanding thermal conductivity of 22 W/cm·K, and high carrier mobilities of 4500 cm²/V·s for electrons and 3800 cm²/V·s for holes.4,5 Additionally, diamond possesses remarkably high figure of merits,6 indicating its potential for low-loss, high-temperature, and high-voltage operations. These intrinsic properties make diamond promising for the fabrication of next-generation power devices.Hydrogen-terminated diamond (H-diamond)7-12 and oxygen-terminated boron-doped diamond (B-diamond)13-24 are two p-type channel layers used in fabricating field-effect transistors (FETs). The H-diamond has surface conductivity induced by hydrogen termination and surface adsorbed species.12 The H-diamond-based electronic devices are sensitive to environmental factors such as humidity, temperature, and surface contamination, leading to instability over a long time.25 On the other hand, the B-diamond exhibits bulk conductivity due to substitute boron atoms incorporated into the diamond lattice during growth. The B-diamond-based electronic devices are believed to be stable at high operating temperatures. Recent studies have demonstrated that B-diamond metal-oxide-semiconductor FETs (MOSFETs) fabricated on smooth epitaxial layers (root mean square roughness: 0.15~0.3 nm) exhibit high electrical performance, good thermal stability, and reproducibility. 14-17 The drain current (ID) was strongly dependent on both the boron doping concentration (Nboron) and the doping thickness (tboron) in the B-diamond channel. At the Nboron of 1016 cm-3 level, when the tboron was 800 nm, the maximum absolute drain current (|ID,max|) for the B-diamond MOSFET operating at room temperature (298 K) was 0.004 mA/mm.14 When the tboron is increased to be 2650 nm, the |ID,max| was enhanced to be 1.2 mA/mm.16 This represents a 300-fold enhancement in the |ID,max| due to the increased tboron at the same Nboron level. Similarly, at the Nboron of 1017 cm-3 level, the |ID,max| was 0.00012 mA/mm at tboron=150 nm and rose to be more than 4000 times of 0.49 mA/mm at tboron=700 nm.17 Meanwhile, with the similar tboron of 700~800 nm, the |ID,max| was increased from 0.004 mA/mm to 0.49 mA/mm due to the variation of the Nboron level from 1016 cm-3 to 1017 cm-3.14,17 Therefore, to further improve |ID,max| in B-diamond MOSFETs, both higher Nboron level and increased tboron in the channel layer are essential.In this study, the B-diamond MOSFETs are fabricated on an epitaxial layer with a Nboron of 1017 cm-3 level and a tboron of 1514 nm. Their electrical characteristics are evaluated at operating temperatures of 298 K, 573 K, and 673 K. The effects of post-annealing at 773 K for the B-diamond MOSFETs are also examined. Furthermore, the influence of doping profile on the electrical performance of B-diamond MOSFETs is systematically summarized.II. EXPERIMENTAL DETAILSThe fabrication process for the B-diamond MOSFETs was reported previously.15 A B-diamond epitaxial layer was deposited on a well-polished Ib-type (100) diamond substrate via a microwave plasma-assisted chemical vapor deposition technique at approximately 1000 °C and 18.6 kPa with the source gases of H₂ and CH₄.26 Boron doping was achieved by utilizing residual boron in the chamber from prior B-diamond growth. The boron concentration profile within the epitaxial layer was characterized using the secondary ion mass spectrometry (SIMS) technique.The B-diamond epitaxial layer was treated at 300 °C for 3 hours in a mixed solution of H₂SO₄ and HNO₃ to convert hydrogen-terminated surface to oxygen-terminated one. Following this treatment, the surface was sequentially coated with LOR5A and AZ5214E photoresists using a spin coater. The LOR5A layer was baked at 180 °C for 5 minutes, while the AZ5214E layer was baked at 110 °C for 2 minutes. Lithographic patterning was performed using a DL-1000 scanning maskless lithography system and followed by developing in a 2.38% tetramethylammonium hydroxide solution for approximately 2.5 minutes. The source/drain electrodes, consisting of a Ti/Au bilayer (10/150 nm), were deposited on the B-diamond surface using an electron-gun evaporation system with evaporation rates of 1 Å/s for Ti and 2 Å/s for Au. The Ti/Au electrodes were annealed at 550 °C for 20 minutes using a rapid thermal annealing system to form Ohmic contacts. An Al₂O₃ gate dielectric layer, approximately 27 nm thick, was deposited via an atomic layer deposition technique at 250 °C using trimethylaluminum and ozone as precursors. A Ti/Pt bilayer (10/100 nm) was employed as the gate electrode. To expose the source/drain electrodes, contact windows were opened by etching the Al₂O₃ layer using a capacitively coupled plasma reactive ion etching system in a CHF₃/Ar atmosphere. The etching conditions were plasma power of 100 W, chamber pressure of 3.0 Pa, CHF₃ flow rate of 10 sccm, and Ar flow rate of 40 sccm. The electrical properties of B-diamond MOSFETs were investigated at 298 K, in-situ 573 K annealing, and in-situ 673 K annealing. For both in-situ 573 K and 673 K annealing, a stabilization time of 30 minutes was applied. Since it was confirmed that post-annealing at 773 K (ex-situ 773 K) for the B-diamond MOSFETs can enhance their room temperature performance,23 the electrical characteristics of them after ex-situ 773 K annealing for 30 minutes were also examined. III. EXPERIMENTAL RESULTSA. Surface morphology for the B-diamond MOSFETFigure 1(a) presents a scanning electron microscopy (SEM) image of the B-diamond MOSFET. The circular-shaped drain electrode has a diameter of 300 μm. The gate width (WG) of the MOSFET is calculated to be 0.942 mm. Fig. 1(b) shows a magnified view of the red square region highlighted in Fig. 1(a). Despite the use of multiple exposures during the lithography process for the circular electrodes, edge irregularities remain due to limitations in system resolution, defocus, or aliasing effects [indicated by red arrows in Fig. 1(b)]. A schematic illustration of the B-diamond MOSFET is provided in Fig. 1(c), where the gate length (LG), the spacing length between the source and gate electrodes (LS-G), and the spacing length between the drain and gate electrodes (LD-G) are 2.8, 4.3, and 4.3 μm, respectively. Fig. 1(d) displays the SIMS measurement of the boron concentration profile in the B-diamond epitaxial layer, revealing the Nboron on the level of 1017 cm-3 and the tboron of 1514 nm.B. Electrical properties of the as-fabricated B-diamond MOSFETFigure 2(a) presents the ID as a function of drain voltage (VD) for the as-fabricated B-diamond MOSFET operating at 298 K. The gate-source voltage (VGS) varies from –20.0 V to 42.0 V in 2.0 V increments. The MOSFET exhibits p-type transistor behavior. The |ID,max| reaches 4.7 mA/mm, which is significantly higher than the previously reported maximum value of 1.2 mA/mm.16,24 This enhancement is attributed to the combined effects of a relatively higher Nboron and thicker tboron. The ID–VD characteristic for the B-diamond MOSFET does not exhibit clear saturation. This behavior is intrinsic to heavily boron doping in the diamond. The high boron concentration results in bulk conduction, and the depletion region cannot extend through the entire 1514 nm‑thick doped layer. Consequently, the full pinch‑off for the B-diamond MOSFETs cannot be achieved.Figure 2(b) shows the transfer characteristic (–VGS) of the B-diamond MOSFET at 298 K. From the fitted data, the threshold voltage (VTH) is extracted to be as high as 320.2 ±5.0 V. Higher Nboron and thicker tboron contribute to a relatively large number of holes compared to the reports in Refs. 16 and 24, resulting in the high |ID,max| and difficulty in turning the MOSFET off. Because the B‑diamond MOSFET exhibits an extremely large VTH, the equipment measurement range cannot reach the true off‑state in the ID-VGS characteristic. As a result, the off current cannot be reliably determined. Consequently, the on/off ratio, subthreshold swing, and extrinsic transconductance of the MOSFETs cannot be extracted and are therefore not discussed in this manuscript.C. Electrical properties of the B-diamond MOSFETs at in-situ 573 and 673 KFigures 3(a) and 3(b) show the ID–VD and –VGS characteristics of the B-diamond MOSFET operating at in-situ 573 K, respectively. The |ID,max| reaches 76.9 mA/mm, significantly higher than the value of 4.7 mA/mm at 298 K and the previously reported value of 10.9 mA/mm at in-situ 573 K.16 This enhancement is primarily attributed to the thermal activation of boron acceptors and higher Nboron. The VTH for the B-diamond MOSFET at in-situ 573 K is as large as 1143.2 ±20.0 V. Figs. 3(c) and 3(d) demonstrate the ID–VD and –VGS characteristics for the B-diamond MOSFET operating at in-situ 673 K, respectively. The |ID,max| further increases to 109.2 mA/mm with the VTH of 893.3 ±20.0 V. The ID–VD characteristics of the B‑diamond MOSFETs at in‑situ 573 K and 673 K show that the VGS modulation of the ID becomes much weaker than at 298 K. Because boron has a high activation energy of 0.37 eV, only a small fraction of acceptors is ionized at 298 K, and the VGS can effectively modulate the channel. At 573 K and 673 K, however, many boron atoms become ionized, causing the hole concentration to increase by several orders of magnitude. The channel conduction is then dominated by thermally activated bulk carriers, and the gate field can no longer deplete the thick heavily doped layer. As a result, the VGS modulation of ID becomes significantly weaker at elevated temperatures. For the same reason, much larger positive VGS values are required to deplete the thick (1514 nm) doped layer at elevated temperatures, indicating the increase of VTH values.D. Electrical properties of the B-diamond MOSFETs after ex-situ 773 KFigures 4(a) and 4(b) demonstrate the ID–VD and –VGS characteristics for the B-diamond MOSFET after ex-situ 773 K annealing and measured at 298 K, respectively. Compared to that (4.7 mA/mm) of the as-fabricated MOSFET, the |ID,max| for the annealed one increases to 6.0 mA/mm with a lower VTH of 258.7 ±5.0 V. The enhancement in electrical performance after 773 K annealing is in good agreement with the previous conclusion.23 In order to clarify the reason, the capacitance-voltage (C-V) characteristics for the B-diamond MOS capacitors operating at 298 K and after ex-situ 773 K annealing are investigated and shown in Figs. 4(c) and 4(d), respectively. In both C-V curves, the measurement frequency is 5 kHz. The VGS is swept from 5.0 V to -15.0 V, followed by a reverse sweep from -15.0 V to 5.0 V. Three key modifications in the electrical properties of Al₂O₃/B-diamond MOS capacitors are observed after ex-situ annealing at 773 K. First, the maximum oxide capacitance (COX) increases from 0.244 μF/cm² to 0.301 μF/cm², indicating an enhancement in the dielectric constant for the Al2O3. Second, both C–V curves shift negatively relative to 0 V, suggesting the presence of positive charges in the MOS capacitors,27 likely due to oxygen vacancies or carbon–oxygen dangling bonds. However, after annealing, the magnitude of the negative voltage shift is reduced, implying a decrease in positive charge density close to the Al2O3/B-diamond interface. Third, the hysteresis voltage shift (Vhys), defined as the voltage difference between forward and reverse sweep directions, decreases from 3.4 V to 1.4 V after ex-situ 773 K annealing. This reduction indicates a lower trapped charge density in the Al2O3 film after annealing.28 These observations are consistent with reduced Fermi‑level pinning at the Al₂O₃/B‑diamond interface after annealing. Overall, the improved qualities of the Al₂O₃ insulator and the Al₂O₃/B-diamond interface contributes to an increase in |ID,max| and a reduction in the VTH of the B-diamond MOSFETs.IV. DISCUSSIONSTable 1 summarizes the electrical properties of B-diamond metal-semiconductor FETs (MESFETs) and MOSFETs. The |ID,max| of the B-diamond MOSFET operating at 298 K in this work is higher than the previous studies.13-24 However, it still remains lower than that of H-diamond-based MOSFETs.7-11 In contrast, B-diamond MOSFETs operating at in-situ 573 K and 673 K annealing exhibit |ID,max| values that are comparable to those of the H-diamond MOSFETs.29 Figures 5(a) and 5(b) summarize the dependence of |ID,max| and VTH on the tboron and Nboron for previously reported B-diamond MESFETs and MOSFETs.13-24 The circular, square, and triangular markers represent the Nboron in levels of 1015, 1016, and 1017 cm-3, respectively. Variations in LG, LS-G, and LD-G in Ref. 14 do not significantly affect |ID,max| and VTH. Similarly, despite differences in VGS and VD for the B-diamond MESFET and MOSFET in Refs. 21 and 23, respectively, the values of |ID,max| and VTH remain relatively stable. Therefore, the effects of LG, LS-G, LD-G, oxide capacitance (COX), VGS, and VD are not considered in Figs. 5(a) and 5(b). Meanwhile, we do not distinguish whether full off states are achieved in the B‑diamond MOSFETs. At a fixed Nboron, both |ID,max| and VTH increase with increasing tboron. For instance, at Nboron level of 1016 cm-3, |ID,max| increases from 0.004 mA/mm at tboron =800 nm to 1.2 mA/mm at tboron =2650 nm, while VTH rises from 3.2 V to 63.8 V.14, 16 At the Nboron level of 1017 cm-3, |ID,max| increases from 0.00012 mA/mm at tboron =150 nm to 4.7 mA/mm at tboron =1514 nm, with VTH increasing from –8.0 V to 320.2 ±5.0 V.17 Furthermore, at a similar tboron of 700–800 nm, increasing Nboron from 1016 cm-3 to 1017 cm-3 results in a rise in |ID,max| from 0.004 mA/mm to 0.49 mA/mm and in VTH from 3.2 V to 63.2 V.14, 23There is a fundamental relationship between the tboron, boron acceptor concentration (NA), and the VTH.,                     (1)Here, VFB, q, εdia, and ε0 are flat-band voltage shift determined by the metal/B‑diamond work‑function difference, elementary charge, permittivity of the diamond, and vacuum permittivity, respectively. Equation (1) shows that the VTH increases with both the NA and square of tboron. A higher Nboron results in a larger NA, and a thicker tboron contains a larger total charge. To turn off the device, the gate must deplete this charge by expanding the depletion region through the entire doped layer. A larger NA and thicker tboron therefore require a stronger electric field, leading to a higher VTH.The relationships between the ID,max and VTH can be expressed as:,                     (2)where μeff is effective mobility for the B-diamond channel. In p‑type B‑diamond MOSFETs, a negative VGS induces hole accumulation. A larger VTH value corresponds to a larger , indicating the higher |ID,max|. Consequently, the |ID,max| also increases with both the Nboron and tboron.The current challenge for the B-diamond MOSFETs is to further enhance |ID,max| while maintaining a low VTH (<10 V). For instance, the B-diamond MOSFET with the Nboron and tboron of 1017 cm-3 level and 230 nm, respectively, achieves a VTH of 7.0 V, but the |ID,max| is as low as 0.0019 mA/mm.18,19 Zhu et al. attempted to increase the Nboron to the range of 1015~1019 cm-3 using a thin tboron of 45 nm to address this issue.24 However, growing such a thin layer with high and uniform boron concentration remains a significant challenge. On the other hand, techniques such as ion implantation or selective heavy doping in the source/drain regions could be a good choice to reduce the Ohmic contact resistance for improving the |ID,max|.V. COUNCLUSIONSIn conclusion, the B-diamond MOSFET fabricated on an epitaxial layer with the tboron of 1514 nm and Nboron level of 1017 cm⁻³ exhibits |ID,max| values of 4.7 mA/mm, 76.9 mA/mm, and 109.2 mA/mm at 298 K, in-situ 573 K, and in-situ 673 K, respectively. The corresponding VTH values are 320.2  ±5.0 V, 1143.2 ±20.0 V, and 895.1 ±20.0 V. After ex-situ annealing at 773 K and measured at 298 K, the device shows improved performance with |ID,max| and VTH reaching 6.0 mA/mm and 258.7 ±5.0 V, respectively. The influence of the doping profile on the electrical performance of B-diamond MESFETs and MOSFETs is summarized. At a constant Nboron, both the |ID,max| and VTH increase with increasing tboron. Meanwhile, at a similar tboron, these parameters also increase with higher Nboron.ACKNOWLEDGEMENTSThis work is supported by the JSPS KAKENHI Projects (23K03966 and 20H05661), MEXT Q-LEAP (JPMXS0118068379), JST CREST (JPMJCR1773), JST Moonshot R&D (JPMJMS2062), MIC R&D for construction of a global quantum cryptography network (JPMI00316), and ARIM (JPMXP1225WS0451 and JPMXP1225NM5076) of the Ministry of Education, Culture, Sports, Science and Technology, Japan. The authors would like to thank the technical support from Dr. Kashiwagi at the Research Organization for Nano & Life Innovation in Waseda University.Data Availability StatementsThe data that support the findings of this study are available from the corresponding author upon reasonable request.14Table 1 Summary of electrical properties for the B-diamond MESFETs and MOSFETs.13-24  Temperature(K) Nboron level(cm-3) tboron(nm) COX(μF/cm2) LG(μm) LS-G(μm) LD-G(μm) VGS(V) VD(V) |ID,max|(mA/mm) VTH(V) MESFET [13] 298 K 1015 3000 - 20 5 30 0 -20 0.06 27  In-situ 573 K 1015 3000 - 20 5 30 0 -20 0.12 - MOSFET [14] 298 K 1016 800 0.157 3.7 7.3 8.9 -16.0 -16.0 0.003 3.4  298 K 1016 800 0.157 5.4 11.8 13.9 -16.0 -16.0 0.004 3.2  298 K 1016 800 0.157 10.3 9.9 13.6 -16.0 -16.0 0.002 0.8 MOSFET [15] 298 K 1016 2000 0.288 5.6 9.8 15.3 -6.0 -16.0 0.11 58.8  Ex-situ 773 K 1016 2000 - 5.6 9.8 15.3 -6.0 -16.0 0.34 32.0 MOSFET [16] 298 K 1016 2650 0.266 2.6 5.8 4.6 -20.0 -16.0 1.2 63.8  In-situ 573 K 1016 2650 0.266 2.6 5.8 4.6 -20.0 -16.0 10.9 31.2 MOSFET [17] 298 K 1017 150 0.342 3.0 5.0 11.3 -16.0 -16.0 0.00012 -8.0 MOSFET [18] 298 K 1017 230 0.398 3.0 4.0 3.0 -5.0 -10.0 0.0019 7.0 MOSFET [19] 298 K 1017 230 0.398 5.0 3.0 9.0 -5.0 -10.0 0.0002 -  Ex-situ 773 K 5×1016 500 0.199 4.0 3.0 4.0 -16.0 -20.0 0.12 >20 MOSFET [20] 298 K 1017 230 0.398 2.0 4.0 10.0 -10.0 -40.0 0.12 -  In-situ 523 K 1017 230 0.398 2.0 4.0 10.0 -10.0 -40.0 8.0 - MESFET [21, 22] 298 K 1017  700 - 4.3 10.4 26.1 -2.0 -10.0 0.39 64.0  Ex-situ 773 K 1017  700 - 4.3 10.4 26.1 -2.0 -10.0 0.55 64.2 MOSFET [23] 298 K 1017  700 0.234 7.0 9.9 17.4 -16.0 -16.0 0.49 63.2  Ex-situ 773 K 1017  700 0.269 7.0 9.9 17.4 -16.0 -16.0 0.60 56.1 MOSFET [This work] 298 K 1017  1514 0.244 2.8 4.3 4.3 -20.0 -20.0 4.7 320.2  In-situ 573 K 1017  1514 - 2.8 4.3 4.3 -20.0 -20.0 76.9 1143.2  In-situ 673 K 1017  1514 - 2.8 4.3 4.3 -20.0 -20.0 109.2 893.3  Ex-situ 773 K 1017  1514 0.301 2.8 4.3 4.3 -20.0 -20.0 6.0 258.7 MOSFET [24] 298 K 1015~1019 45 - 4.0 - - -6.0 -15.0 1.2 3.2FIG. 1. (a) SEM image of the B-diamond MOSFET. (b) Enlarged view of the red square region indicated in Fig. 1(a). (c) Schematic illustration of the B-diamond MOSFET structure. (d) SIMS depth profile showing the Nboron and tboron in the B-diamond epitaxial layer.FIG. 2. (a) ID–VD and (b) –VGS characteristics for the B-diamond MOSFET operating at 298 K, respectively.FIG. 3. (a) ID–VD and (b) –VGS characteristics for the B-diamond MOSFET operating at in-situ 573 K, respectively. (c) and (d) Those for the B-diamond MOSFET operating at in-situ 673 K, respectively.FIG. 4. (a) ID–VD and (b) –VGS characteristics for the B-diamond MOSFET after ex-situ 773 K annealing, respectively. (c) and (d) C-V characteristics for the B-diamond MOS capacitors operating at 298 K and after ex-situ 773 K annealing, respectively.FIG. 5. (a) and (b) Summary of the dependence of |ID,max| and VTH on tboron and Nboron for B-diamond MESFETs and MOSFETs, respectively.References1. S. Hino, T. Hatayama, J. Kato, E. 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Meeting, 15-17 December 2014, San Francisco, CA, USA.image2.pngimage3.pngimage4.pngimage5.pngimage6.emf100 μmGateDrainSourceGateSourceDrainGateSourceDrainDiamond (100)Source DrainBoron-doped diamond2.8 μm4.3 μmGate4.3 μmALD-Al2O3 (~27 nm)5 μmBoron concentration (cm-3)Depth (nm)(a)  (b)(c)(d)tboron: 1514 nmNboronlevel: 1017cm-3image7.emf0−4 −8 −12 −16 −200−1−2−3−4−5ID  (mA/mm)VD(V)VGS: –20.0 ~ 42.0 VStep: +2.0 V(mA0.5/mm0.5)VGS(V)VGS= –20.0 V VTH=320.2 V(a)(b)MOSFET @ 298 KMOSFET @ 298 Kimage8.emf0−4 −8 −12 −16 −200−20−40−60−80ID  (mA/mm)VD(V)VGS: –20.0 ~ 42.0 VStep: +2.0 VVGS= –20.0 V (a) MOSFET @ in-situ 573 KVTH= 1143.2 VID  (mA/mm)VD(V)VGS: –20.0 ~ 42.0 VStep: +2.0 VVGS= –20.0 V (b) MOSFET @ in-situ 673 KVTH= 893.3 V(mA0.5/mm0.5)VGS(V)(mA0.5/mm0.5)VGS(V)(c) MOSFET @ in-situ 573 K(d) MOSFET @ in-situ 673 Kimage9.emf0−4−8 −12 −16 −200−1−2−3−4−5−6−7ID  (mA/mm)VGS: –20.0 ~ 42.0 VStep: +2.0 V(mA0.5/mm0.5)VGS(V)VGS= –20.0 V VTH=258.7 V(a)(b)MOSFET @ after ex-situ 773 KVD(V)Capacitance(μF/cm2)VGS(V)Capacitance(μF/cm2)VGS(V)(d) After ex-situ 773 K(c) 298 KVhysVhys=3.4 VVhys=1.4 VMOSFET @ after ex-situ 773 Kimage10.emf05001000 1500 2000 2500 300010−510−410−310−210−1100101   1017cm-31015cm-31016cm-31017cm-31015cm-31016cm-3|ID,max|(mA/mm)tboron(nm)VTH(V)tboron(nm)(a)(b)image1.png