Low-Temperature Transport Properties of Holes Introduced by Ionic Liquid Gating in Hydrogen-Terminated Diamond Surfaces

Abstract

The surface conductivity of (111)-and (100)-oriented hydrogen-terminated diamonds was investigated at low temperatures for different carrier densities. The carrier density was controlled in a wide range in an electric doublelayer transistor configuration using ionic liquids. As the carrier density was increased, the temperature dependences of sheet resistance and mobility changed from semiconducting to metallic ones: the sheet resistance and mobility for the (111) surface were nearly independent of temperature for a sheet carrier density of %4 Â 10 13 cm À2 , indicating metallic carrier transport. It was also found that the interface capacitance, determined from the gate voltage dependence of the Hall carrier density, depended significantly on the crystal orientation.

Towards the insulator-to-metal transition at the surface of ion-gated nanocrystalline diamond films

“…Horizontal and vertical error bars indicate the difference in the values of ∆n 2D and R determined between the charge and discharge of the EDL capacitor respectively. The maximum values of ∆n 2D are more than 3 times larger than the ones in earlier reports [12][13][14][15][16][17]. The negative slope of ∆R/R ′ for increasing hole density indicates that charge transport is dominated by holonic carriers, consistent with the preliminary Hall measurements on the pristine film.…”

“…This likely stems from an increase in the EDL capacitance due to the sizable concentration of mobile carriers already at V G = 0. Despite this advantage, the sheet conductance of the AL in our NCD films remains up to ∼ 10 times smaller than the ones reported in undoped epitaxial films and single-crystals upon field-effect doping in the entire T range [14][15][16][17], and the AL is unable to cross to the metallic side of the MIT even for the largest values of ∆n 2D . This can not be simply attributed to the presence of grain boundaries, since the bulk conductivity is firmly in the disordered metal regime.…”

“…The electric-double-layer (EDL) transistor is a particularly effective field-effect architecture, thanks to the large electric field that develops at a solid/electrolyte interface when a voltage drop is applied across it [11]. The electric transport properties of diamond-based EDL transistors have been extensively studied [12][13][14][15][16][17], but no evidence was reported for either SC or good metallic behavior. This can be associated with the relatively modest charge carrier densities achieved in these works on insulating single crystals and epitaxial thin films ( 7 ·10 13 cm −2 [12][13][14][15][16][17]) with respect to the values typically obtained in conducting systems (≃ 10 14 − 10 15 cm −2 [18][19][20][21][22][23][24]).…”

Diamond surface conductivity: Properties, devices, and sensors

“…12 , 13 As a result, the low temperature behavior of this system has not been extensively probed. Recently, Yamaguchi et al 14 showed that an evolution from semiconducting to metallic conduction can be obtained as the hole sheet density is increased using Figure 1. (a) Schematic picture of a hydrogen-terminated diamond surface in contact with a water layer and the evolution of band bending during the resulting electron transfer across the diamond-water interface.…”

Conductivity Modulation by CaVO₃-based All-solid-state Redox Transistor with Ion Transport of Li⁺ or H⁺

“…Recently, in situ control of electronic carrier through ion transport in nanoscale has been attracting attention for nanoelectronics devices [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Physical properties such as electronic conductivity, magnetoresistance and superconducting critical temperature were tuned by the similar method [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The redox transistor employs electrochemical carrier doping by electrochemical reduction and oxidation (redox) due to the ion transport.…”