Schottky Barrier Height Modulation of Zr/p-Diamond Schottky Contact by Inserting Ultrathin Atomic Layer-Deposited Al₂O₃

We fabricated Zr/p-diamond Schottky barrier diodes (SBDs) with and without a ultrathin atomic layer-deposited Al2O3 interlayer. The effects of the Al2O3 interlayer on the electrical properties of devices were investigated using the current-voltage (I-V) and capacitance-voltage (C-V) characteristics at room temperature. Compared with Zr/p-diamond SBDs without the interlayer, SBDs with a 2-nm-thick Al2O3 interlayer exhibited higher Schottky barrier height and breakdown voltage. The insertion of the Al2O3 layer effectively reduced the interface state and it is considered that the barrier enhancement is attributed to the significant reduction of interface state density. This work provides a simple method to passivate the diamond surface and modulate the barrier heights of diamond SBDs.