Effect of rapid thermal annealing on performances of vertical boron-doped diamond Schottky diode with LaB₆ interlayer

We demonstrated the fabrication and operation of vertical diamond Schottky barrier diodes (SBDs) by inserting an ultrathin lanthanum hexaboride (LaB₆) interlayer at the Zr/diamond interface. The rapid thermal annealing (RTA) effect on SBD electrical properties was investigated systematically by employing current–voltage and capacitance–voltage measurements. The results reveal that a suitable RTA treatment can significantly improve the device performance of diamond SBD with LaB₆. After 350 °C annealing, a significant improvement of rectifying current curve with a forward current density over 2 kA/cm² is obtained, and this device also exhibits excellent diode behaviors with extremely high rectification ratio of 1.7 × 10¹⁰ and low series resistance of 0.79 mΩ·cm², combining with Schottky barrier height of 1 eV, ideality factor of 1.78, and turn-on voltage of 2.3 V. Additionally, after 350 °C annealing, the turn-on voltage reduces while maintaining a reasonable breakdown performance. There is a process temperature window between 250 and 450 °C for RTA to obtained optimized Schottky interface. The RTA treatment can make certain effective improvement for this SBD via interface engineering.