Annealing Temperature on Contact Properties between Nickel Film and Hydrogen-Terminated Single Crystal Diamond

Pengfei Zhang,Shaopeng Zhang,Hong-Xing Wang,Weidong Chen,Wen Ma,Shufang Yan

doi:10.3390/coatings10090876

Abstract

Ohmic contact of nickel on hydrogen-terminated single-crystal diamond film was investigated with an annealing temperature ranging from room temperature to 750 °C in hydrogen atmosphere. Nickel film was deposited on a hydrogen-terminated single-crystal diamond surface with gold film in order to protect it from oxidation. Contact properties between nickel and hydrogen-terminated single crystal diamond were measured by a circular transmission line model. The lowest specific contact resistivity was 7.82 × 10−5 Ω cm2 at annealing temperature of 750 °C, indicating good ohmic contact, which reveals improved thermal stability by increasing temperature.

Highlights

The activation energies are too large to utilize the conventional doping technology for diamond dopants (370 meV for boron and 570 meV for phosphorus) as it is difficult for them to be activated at room temperature (RT)
A new technology breaks this deadlock by treating diamond with hydrogen plasma to form hydrogen termination on a diamond (H-diamond) surface, which generates two-dimensional hole gas (2DHG)
H-diamond surface were on H-diamond with photolithography, electron beam evaporation (EB)

Summary

Introduction

Diamond has many attractive properties as a semiconductor, such as wide band gap (5.47 eV), large breakdown field (>10 MV cm−1 ), high saturation velocities (1.5 × 107 cm s−1 for electrons and 1.05 × 107 cm s−1 for holes), high carrier mobility (4500 cm V−1 s−1 for electrons, 3800 cm V−1 s−1 for holes), and highest thermal conductivity (22 W cm−1 K−1 ), making it a promising semiconductor for future high-frequency, high-power, and high-temperature electronic devices, such as metal-oxide-semiconductor field effect transistors (MOSFETs), which have been studied extensively [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. A new technology breaks this deadlock by treating diamond with hydrogen plasma to form hydrogen termination on a diamond (H-diamond) surface, which generates two-dimensional hole gas (2DHG) (density: 1013 cm−2 ; mobility: 50–150 cm V−1 s−1 ). This 2DHG layer resides several nanometers below the diamond surface which possesses many characteristics such as an almost-constant current density within a temperature range from 20 to 300K and ease of fabrication [9,12]. It is necessary to find electrode materials to achieve good ohmic contact between the electrode layer and the H-diamond surface, by which superior diamond electronic devices could be developed. A nickel circular transmission properties between nickel and H-diamond

Materials and Methods

Results and Discussion

Conclusions