Potential barrier heights at metal on oxygen-terminated diamond interfaces

Abstract

Electrical properties of metal-semiconductor (M/SC) and metal/oxide/SC structures built with Zr or ZrO 2 deposited on oxygen-terminated surfaces of (001)-oriented diamond films, comprised of a stack of lightly p-doped diamond on a heavily doped layer itself homoepitaxially grown on a Ib substrate, are investigated experimentally and compared to different models. In Schottky barrier diodes, the interfacial oxide layer evidenced by high resolution transmission electron microscopy and electron energy losses spectroscopy before and after annealing, and barrier height inhomogeneities accounts for the measured electrical characteristics until flat bands are reached, in accordance with a model which generalizes that of R.T. Tung [Phys. Rev. B 45, 13509 (1992)] and permits to extract physically meaningful parameters of the three kinds of interface: (a) unannealed ones, (b) annealed at 350℃, (c) annealed at 450℃ with characteristic barrier heights of 2.2-2.5 V in case (a) while as low as 0.96 V in case (c). Possible models of potential barriers for several metals deposited on well defined oxygen-terminated diamond surfaces are discussed and compared to experimental data. It is concluded that interface dipoles of several kinds present at these compound interfaces and their chemical evolution due to annealing are the suitable ingredients able to account for the Mott-Schottky behavior when the effect of the metal work function is ignored, and to justify the reverted slope observed regarding metal work function, in contrast to the trend always reported for all other metal-semiconductor interfaces.

An insight of p-type to n-type conductivity conversion in oxygen ion-implanted ultrananocrystalline diamond films by impedance spectroscopy

“…[36][37][38] The O-terminated diamond surface vanished after 400 o C annealing in vacuum. 39 While Thomas Lechleitner et al 40 Figure S1) As one of the source gases during CVD process, hydrogen makes the diamond grains H-terminated and such surface induces p-type surface conductivity. 41 This is in agreement with impedance measurement results, where the nanocrystalline diamond grains in p-type are more conductive than those in n-type O + -implanted films.…”

Barrier Heights of Au on Diamond with Different Terminations Determined by X-ray Photoelectron Spectroscopy

“…From the equation of u(x) ≡ Ev(x) − EF, when x = 0, u(0) = EV(0) − EF = −ΦBH = −1.71 eV. So, the width of the space charge region can be calculated by Equations (8) and (9) as x1 = 1.30 μm. By using the same method, the width of the space charge region for Au/F-/Ndiamond and diamond with Ar + bombarded surface can be calculated as x2 = 1.47, x3 = 1.50 and x4 = 1.34 μm, respectively.…”

“…For example, contacts made by metal/H-diamond are likely to show ohmic characteristics or low Schottky barrier heights [6]. Contacts made by metal/O-diamond and metal/F-diamond usually have relatively high Schottky barrier heights [7,8], which will be reduced by annealing for metal/O-diamond contacts [9]. N-diamond is a quite new type of diamond surface termination [2].…”

Hole injection contribution to transport mechanisms in metal/p−/p++ and metal/oxide/p−/p++ diamond structures

“…Taking into account the image force effect which adds 0.04 V to the barrier at flat bands [7,9] and the calculated energy difference between the bulk Fermi level and valence band top of 0.38 eV from data in [1], the applied voltage needed to induce flat bands amounts to 0.63 V, as indicated in Fig. 1.…”