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The ohmic contact resistance (${R}_{C}$), surface resistance (${R}_{S}$), and channel resistance (${R}_{\text {CH}}$) of hydrogen-terminated diamond (H-diamond) MOSFETs were investigated in this study. Planar-type and T-type H-diamond MOSFETs were employed to analyze them. Because no interspaces exist between the source–drain and gate electrodes for the T-type H-diamond MOSFETs, then ${R}_{S}$ is zero. Both planar-type and T-type MOSFETs show low leakage current densities and good operations. By considering the relationships between the total resistance (${R}_{ \mathrm{\scriptscriptstyle ON}}$) and 1/ $\vert $ gate voltage-threshold voltage $\vert $ , ${R}_{C}$ and ${R}_{\text {CH}}$ for the T-type H-diamond MOSFET at a gate voltage of −10.0 V are determined to be 13.8 and 21.8 $\Omega \cdot $ mm, respectively. As ${R}_{C}$ for both MOSFETs is the same, ${R}_{S}$ and ${R}_{\text {CH}}$ for the planar-type H-diamond MOSFET are deduced to be 90.0 and 15.8 $\Omega \cdot $ mm, respectively. ${R}_{S}$ accounts for 75.3% of ${R}_{ \mathrm{\scriptscriptstyle ON}}$ for the planar-type H-diamond MOSFET, which is the main reason for its lower drain current and extrinsic transconductance than those of the T-type MOSFET. Although ${R}_{S}$ is suppressed for the T-type H-diamond MOSFET, ${R}_{C}$ occupies 38.8% of ${R}_{ \mathrm{\scriptscriptstyle ON}}$. To further improve the performance of the H-diamond MOSFETs, it is important to eliminate ${R}_{S}$ and decrease ${R}_{C}$ to further improve the electrical properties of the H-diamond MOSFETs. [ABSTRACT FROM AUTHOR]

Boron-doped diamond (B-diamond) metal–oxide–semiconductor (MOS) capacitor and MOS field-effect transistor (MOSFET) are fabricated on a flat diamond epitaxial layer. Their electrical properties and thermal stabilities after annealing at 500 °C are investigated. Annealing makes the leakage current density of the B-diamond MOS capacitor increase slightly. There is a larger stretch-out for the capacitance-voltage curve in the depletion region after annealing than that before annealing. The drain-current maxima for the as-fabricated and 500 °C-annealed MOSFETs are obtained as −0.49 and −0.60 mA/mm, respectively. Extrinsic transconductance maxima are 18.7 and $21.4~\mu \text{S}$ /mm, respectively. These obtained values are considerably larger than those obtained by the previously reported B-diamond MOSFETs. [ABSTRACT FROM AUTHOR]

A super-high dielectric constant AlO x /TiO y nanolaminate film i s grown on hydrogenated diamond (H-diamond) to enable superior metal-oxide-semiconductor (MOS) capacitors and MOS field-effect transistors (MOSFETs). In order to minimize or suppress leakage current, a nanometer thick AlO x film is inserted at the AlO x /TiO y nanolaminate/H-diamond interface. The maximum values for the capacitance density and dielectric constant related to the summation of individual AlO x and nanolaminate are 1.06 μF/cm2 and 68.7, respectively. Capacitance density and dielectric constant for the AlO x /TiO y nanolaminate are as high as 5.22 μF/cm2 and 308, respectively. Electrical properties of four H-diamond MOSFETs with gate lengths increasing from 2.4 μm to 10.1 μm were investigated. All of them showed p-type behavior and distinct pinch-off characteristics with drain current maxima of −47.4, −43.3, −26.6, and −24.6 mA/mm, respectively. On/off ratios and threshold voltages for the MOSFETs are higher than 104 and lower than 0.55 ± 0.10 V, respectively. The low threshold voltages indicate that the AlO x /TiO y nanolaminate gate-based MOSFETs can switch between ON and OFF stages at low gate voltages. Effective mobilities of the H-diamond channel layers for all the MOSFETs raised firstly and dropped subsequently with increasing voltages, which can be explained by the effect of mobility limiting factors. We demonstrate that super-high dielectric constant AlO x /TiO y nanolaminate film on diamond enables superior MOS capacitors and MOSFETs for a new generation of micro/nanoelectronics. Image 1 [ABSTRACT FROM AUTHOR]

In this article, we report the fabrication and characterization of boron-doped diamond (B-diamond) Schottky diodes and MESFETs. Effects of annealing at 573–973 K on the electrical properties of these devices are investigated. Current density maximum for the as-fabricated Schottky diode is 0.05 A/cm2 at a gate voltage of −10.0 V. Annealing at 673 and 973 K makes it increase first to 0.70 A/cm2 and decrease lately to 0.07 A/cm2, respectively. ON/OFF ratios for the as-fabricated B-diamond Schottky diode exceed 4.5 × 108 at the OFF-voltage (VOFF) of 0 V and 3.2 × 106 at VOFF = 42.0 V. For the annealed Schottky diode, the ON/OFF ratios are higher than 1.7 × 106 at VOFF < 6.0} V. Ideality factor and barrier height for Au/Pt bilayer gates on the B-diamond channel layer range from 1.05 to 1.78 and from 1.24 to 1.56 eV, respectively. All three B-diamond MESFETs with the gate lengths of 12.0, 7.0, and 4.3 μm, respectively, operate with p-type channel characteristics. The drain current maxima for the as-fabricated MESFETs are −0.11, −0.16, and −0.39 mA/mm. After annealing at 773 K, these values increase to −0.17, −0.24, and −0.55 mA/mm. Annealing at 773 K also increases the extrinsic transconductance maxima for the three MESFETs from 11.1, 11.0, and 10.4μS/mm to 18.6, 16.2, and 14.4 μS/mm, respectively. [ABSTRACT FROM AUTHOR]

A HfO 2 /Al 2 O 3 multilayer has been deposited by an atomic layer deposition (ALD) technique on a hydrogenated-diamond (H-diamond) epitaxial layer. Electrical properties of the ALD-HfO 2 /Al 2 O 3 /H-diamond metal-insulator-semiconductor (MIS) diode have been investigated to compare with those of the single ALD-Al 2 O 3 /H-diamond and ALD-HfO 2 /H-diamond MIS diodes. The leakage current density for the ALD-HfO 2 /Al 2 O 3 /H-diamond MIS diode is smaller than 3.8 × 10 − 8 A·cm − 2 with electric field ranging from − 1.6 to 1.0 MV·cm − 1 . The dielectric constant for the ALD-HfO 2 /Al 2 O 3 multilayer is larger than that for the single ALD-Al 2 O 3 . The fixed charge density in the ALD-HfO 2 /Al 2 O 3 /H-diamond structure is much lower than that in the single ALD-HfO 2 /H-diamond structure. The electrical properties of the ALD-HfO 2 /Al 2 O 3 /H-diamond MIS field effect transistor have also been investigated. The source–drain current and extrinsic transconductance maxima are − 42.1 mA·mm − 1 and 6.2 ± 0.1 mS·mm − 1 , respectively. The effective mobility for the H-diamond channel layer has been determined to be 38.2 ± 0.5 cm 2 ·V − 1 ·s − 1 . [ABSTRACT FROM AUTHOR]

Thanks to its excellent intrinsic properties, diamond is promising for applications of high-power electronic devices, ultraviolet detectors, biosensors, high-temperature tolerant gas sensors, etc. Here, an overview of high-k oxides on hydrogenated-diamond (H-diamond) for metal-oxide-semiconductor (MOS) capacitors and MOS field-effect transistors (MOSFETs) is demonstrated. Fabrication routines for the H-diamond MOS capacitors and MOSFETs, band configurations of oxide/H-diamond heterointerfaces, and electrical properties of the MOS and MOSFETs are summarized and discussed. High-k oxide insulators are deposited using atomic layer deposition (ALD) and sputtering deposition (SD) techniques. Electrical properties of the H-diamond MOS capacitors with high-k oxides of ALD-Al2O3, ALD-HfO2, ALD-HfO2/ALD-Al2O3 multilayer, SD-HfO2/ALD-HfO2 bilayer, SD-TiO2/ALD-Al2O3 bilayer, and ALD-TiO2/ALD-Al2O3 bilayer are discussed. Analyses for capacitance-voltage characteristics of them show that there are low fixed and trapped charge densities for the ALD-Al2O3/H-diamond and SD-HfO2/ALD-HfO2/H-diamond MOS capacitors. The k value of 27.2 for the ALD-TiO2/ALD-Al2O3 bilayer is larger than those of the other oxide insulators. Drain-source current versus voltage curves show distinct pitch-off and p-type channel characteristics for the ALD-Al2O3/H-diamond, SD-HfO2/ALD-HfO2/H-diamond, and ALD-TiO2/ALD-Al2O3/H-diamond MOSFETs. Understanding of fabrication routines and electrical properties for the high-k oxide/H-diamond MOS electronic devices is meaningful for the fabrication of high-performance H-diamond MOS capacitor and MOSFET gas sensors. [ABSTRACT FROM AUTHOR]

The electrical properties of hydrogen-terminated diamond (H-diamond) metal-insulator--semiconductor field-effect transistor (MISFET) are improved remarkably using AlN/Al2O3 stack gate. Atomic-layer-deposited Al2O3 (ALD-Al2O3) is formed on H-diamond to protect the hole conductive layer at the surface, followed by the sputter-deposited AlN (SD-AlN) under mixed Ar+N2 atmosphere. The insulating property of SD-AlN under mixed Ar+N2 atmosphere is highly improved compared with that of SD-AlN under pure Ar atmosphere. In addition, the positive charges in the SD-AlN are reduced upon the mixed Ar+N2 atmosphere sputter condition. These results could be attributed to the improved electrical properties of H-diamond MISFET and MIS diode with SD-AlN/ALD-Al2O3 stack gate. The MIS diode provides a leakage current density as low as ≈1.25 × 10−6 A cm−2 at gate voltage bias in the range of −20 and +4 V. The capacitance-voltage curve shows an almost no flat-band voltage shift, and the value of effective dielectric constant of SD-AlN approaches close to that of bulk AlN. The MISFET shows normally on depletion mode transfer characteristic. The drain-source current maximum, threshold voltage, and maximum extrinsic conductance of the MISFET with 4 μm gate length are around −58.4 mA mm−1, +1.2 V, and 7.49 mS mm−1. [ABSTRACT FROM AUTHOR]