Pseudo‐Vertical Schottky Diode with Ruthenium Contacts on (113) Boron‐Doped Homoepitaxial Diamond Layers

Abstract

Electrical properties of pseudo‐vertical Schottky barrier diodes (pVSBDs) prepared on (113)–oriented boron doped diamond layers using ruthenium for both the ohmic and Schottky contacts were investigated. First, Ru/Au ohmic contacts were evaporated on homoepitaxial boron doped diamond layers with different resistivity and their specific contact resistance was measured using circular transfer length method structures after annealing at various temperatures up to 750 ˚C. Then, pseudo‐vertical Schottky barrier diode structures were fabricated on the boron doped bi‐layer consisting of a lower, heavily boron‐doped layer ensuring an ohmic contact and an upper, lightly doped layer providing a rectifying Schottky contact. After necessary mesa etching, both contacts were formed by the evaporation Ru/Au bi‐layer. Results show that Ru forms a stable ohmic contact with very low contact resistance (10‐5‐10‐6 Ω.cm2) when deposited on boron doped diamond layers with metallic conductivity. It also provides an acceptable Schottky contact on low‐doped (113) homoepitaxial BDD. Both contacts, which are made simultaneously, realize pVSBDs with low on‐state resistance and low forward voltage drop. However, the lower barrier of the ruthenium contacts results in higher leakage. Ru pVSBDs thus show lower rectification ratio, higher leakage and a worse ideality factor compared to analogical pVSBDs using molybdenum contacts.This article is protected by copyright. All rights reserved.