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 Al
₂
O
₃
interlayer. The effects of the Al
₂
O
₃
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 Al
₂
O
₃
interlayer exhibited higher Schottky barrier height and breakdown voltage. The insertion of the Al
₂
O
₃
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.