The intrinsic charge storage capability of a series of transition metal dichalcogenides (TMDs) (MS2, M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, Mo, Tc, Hf, Ta, W, Re, and MoX2, X = S, Se, Te) is investigated using density functional theory calculations. A map for pseudocapacitor electrodes is provided, depending on the demands of high conductivity and a remarkable peak of density of states (DOS) in the range of the electrolyte window. The calculated DOS suggests that most of the T phase structures are superior to H phase in electroconductibility. The charge storage capability is represented by the number of gaining or losing electrons calculated by integrating DOS in the electrolyte window. MS2 (M = Ti, V, Cr, Fe, Nb, Mo, Tc) of the T phase is conductive and gains electrons easily with considerable valence state change of the TM atom, showing a redox pseudocapacitance character as a cathode. Meanwhile, CoS2–H and MoSe2–T are promising anode materials. Moreover, the chalcogen (S, Se, Te) with different electronegativity and work function will result in the changes of Fermi level and surface polarization of MoX2, leading to the shift of their DOS in the electrolyte window. In another way, the metallic hydrogenated H phase of MoS2 (MoS2H2) with conductivity should have enhanced advanced electrochemical performance.

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In this paper, we propose and experimentally demonstrate a novel lateral AlGaN/GaN diode on Si substrate. The diode features a recessed metal/Al 2 O 3 /III-nitride (MIS)-gated ohmic hybrid anode, in which the drive current can be well controlled by the MIS-Gate and flows between the two ohmic contacts from the anode to the cathode with substantially reduced overall on-resistance (R on ). With this unique architecture, the forward turn-on voltage (V T ) of the diode can be flexibly trimmed, which enables a record low V T of 0.2 V obtained in the proposed diode. The incorporation of high-k dielectric in the recessed gate region and the AlGaN back barrier realize significantly leakage current (I leakage ) reduction yet high breakdown voltage (BV). The BV as high as 1100 V at I leakage less than 1 μA/mm with drift length of 20 μm is achieved in the proposed diode. The unique material properties of Gallium Nitride (GaN) enable excellent figure-of-merit for power electronic devices have been of great interest to researchers and engineers for the past two decades. In the case of lateral devices, the most distinctive feature of GaNbased materials is the high 2-dimensional electron gas (2DEG) density (e.g. ∼1 × 10 13 cm −2 ) generated at the interface of AlGaN/GaN heterojunction, which features exceptional electron mobility as high as ∼2000 cm 2 /V · s at room temperature 1 due to its strong piezoelectric and spontaneous polarization effect.2 Therefore, with the help of the wide bandgap property, the electronic devices based on AlGaN/GaN heterojunction are capable of achieving high switching speed, low switching loss, low conduction loss, high breakdown voltage and high temperature operation, which are highly preferred for power electronic applications.3 For power electronics the AlGaN/GaN on Si substrate has been considered as a promising technology for next generation power devices with low-cost and high performance due to the large diameter wafer up to 8-inch 4-6 and the well developed CMOS compatible process. As a result, the mass fabrication of AlGaN/GaN power devices with the mainstream CMOS fabrication lines becomes feasible. 7,8 Besides featuring the superior power performance, AlGaN/GaN-on-Si power devices can further be monolithically integrated with conventional Si CMOS circuits suggesting the possibility of realizing single-chip compact GaN power integrated circuits (ICs).9 For power applications, most of the aforementioned efforts have been focused on the three-terminal AlGaN/GaN transistors to achieve enhancement-mode (E-mode) operation, 10-15 low leakage current yet high breakdown voltage, [16][17][18] and low current collapse. 19-21On the other hand, the two terminal power diode as an indispensable component for switching power converters also attracts broad attention recently. 22-24In this work, a novel AlGaN/GaN MIS-Gated Hybrid Anode Diode (MG-HAD) that allows flexible control of the forward turn-on voltage (V T ) is demonstrated by simply varying the recess depth at the MIS-Gated region. It features a...