Thermal stabilization and deterioration of the WC/p‐type diamond (100) Schottky‐barrier interface

Abstract

Rectification abilities of tungsten carbide (WC) Schottky‐barrier diodes fabricated on p‐type diamond were confirmed up to 800 K. In this study, electrical properties were used to support the investigation of the WC/diamond interface reaction under elevated temperature. Before heating above 500 K, the interface was not thermally stable. The interface has been stabilized by mean of an annealing under vacuum in the 550–600 K range. This treatment has produced diodes exhibiting large rectification factors of 106 at 3 V, and low leakage currents of 10−12 amps at 100 V in the blocked state, when the operation temperature was below 600 K. However, rectification factors were gradually worsened, while the temperature was exceeding 600 K.

Diamond Schottky diodes with ideality factors close to 1

“…On this graph, dashed-dotted, dashed, and solid lines represent, respectively, J-V characteristics measured at 300 K before heating (initial), measured at 600 K once SBDs electrical properties were stabilized, and measured at 300 K after a total of 90 min of annealing at 600 K. The data of V-SBDs and L-SBDs structures are plotted on thick green and thin red lines, respectively. As previously reported, 10 we observed a shift of log-linear regions to the small voltage side at high temperature due to the temperature contribution in the current increase (see Eq. (1)).…”

“…In the case of Au/p-diamond SBDs, the ideality factor increased when SBDs were heated above 600 K. 9 WC/p-diamond SBDs revealed higher performances than Au-based SBDs; their degradation was obvious above 700 K. 10,11 In addition, the ideality factor of WC/p-diamond SBDs decreased by annealing at approx. 600 K. 10 For these characterizations, we employed lateral SBD structures with ohmic contacts on four corners. As discussed in previous work, 10 at temperature exceeding 500 K, forward currents of WC/p-diamond SBDs were not analyzed well, because of interferences from the large series resistance.…”

“…A* was taken as 90 A cm À2 K À2 , widely employed in the literature. 7,8,10 The J-V characteristics of representative WC/p-diamond V-SBDs and L-SBDs are shown in Fig. 2.…”

“…WC/p-diamond L-SBDs have been heated under vacuum by step at 500 K, at 550 K, and at 600 K, as described elsewhere. 10 Heating steps were approx. 90 min long and separated by cooling steps at 300 K.…”

“…Their thickness was approximately 1 and 0.5 lm for L-SBD and V-SBD structures, respectively, and their boron concentration was around 10 15 cm À3 . 10 After the growth of p-epilayers, remaining graphitic phases were removed by a boiling sulfuric, nitric, and perchloric acids mixture. Then, samples were hydrogenated by H 2 plasma exposition.…”