Ideal SiC Schottky barrier diodes fabricated using refractory metal borides

Abstract

Several refractory metal borides were used as Schottky contacts to fabricate n-type 4H-SiC Schottky diodes. The boride contacts were deposited on SiC substrates held at 20 and 600 °C. Contacts deposited on substrates held at 600 °C produced better diodes with smaller ideality factors from 1.05 to 1.10, barrier heights from 0.94 to 1.15 eV, smaller leakage current densities at a reverse bias of 15 V, and smaller specific on-resistances compared to contacts deposited on substrates held at 20 °C, and these values remained essentially unchanged after annealing at 600 °C for 20 min. The Rutherford backscattering spectroscopy spectra of one of these boride contacts revealed a systematic decrease in oxygen with an increase in the deposition temperature. The improved electrical properties and thermal stability make these boride contacts attractive for high power and high temperature device applications.

A progress report on the MAB phases: atomically laminated, ternary transition metal borides

“…Binary transition metal borides (TMBs) are renowned for their high melting points, hardness, electrical and thermal conductivities, inertness in many corrosive environments, and, sometimes, magnetic properties [1]. For these reasons and others, TMBs have been considered for applications such as wear-resistant coatings, [2,3] cutting tools, [4] thermal diffusion barriers, [5,6] ohmic contacts, [7] heterogeneous catalysis, [8][9][10] high-temperature aerospace components, [11,12] high-temperature electrodes, [13] concentrated solar absorbers, [14] permanent magnets, [15] and primary battery electrodes [16]. From a scientific point of view, binary TMBs alone show unrivalled diversity in crystal chemistry and bonding motifs, with the B atoms' bonding often determined by the M:B ratio.…”

Explorations of boron-based materials through theoretical simulations

“…Boron-based materials have been extensively studied, mainly due to their excellent mechanical properties. Binary boron-based materials is a well-explored field of science where metal (typically a transition metal denoted M) diborides MB 2 [25] , triborides MB 3 [26] , and tetraborides MB 4 [27,28] have all been extensively studied for industrial applications [29][30][31][32][33] . Higher-order boron-based materials, i.e., ternary, quaternary, and quintenary, have recently gained interest as more components often increase the possibility of tuning the materials' properties.…”

Nanoscale transport properties at silicon carbide interfaces

“…More data can be found for the hexagonal polytypes, where the most commonly used metals for Schottky contacts are Ti and Ni, which typically show a higher reproducibility of the barrier height, and have been easily integrated in the fabrication of Schottky diodes. In other works, 'non-conventional' metallization schemes have recently been investigated, such as metal borides [38] or rare earth oxides [39], which should give a better thermal stability of the barrier. First, it must be pointed out that the experimental values of B reported in table 2 are lower than the theoretical ones predicted by the classical Schottky-Mott theory, with a difference of the metal work function and the semiconductor electron affinity [40].…”

“…More data can be found for the hexagonal polytypes, where the most commonly used metals for Schottky contacts are Ti and Ni, which typically show a higher reproducibility of the barrier height, and have been easily integrated in the fabrication of Schottky diodes. In other works, "non conventional" metallization schemes have been recently investigated, like metal borides [38], or rare earth oxides [39], which should give a better thermal stability of the barrier.…”