Recent Advances in β-Ga2O3–Metal Contacts

Abstract

Ultra-wide bandgap beta-gallium oxide (β-Ga2O3) has been attracting considerable attention as a promising semiconductor material for next-generation power electronics. It possesses excellent material properties such as a wide bandgap of 4.6–4.9 eV, a high breakdown electric field of 8 MV/cm, and exceptional Baliga’s figure of merit (BFOM), along with superior chemical and thermal stability. These features suggest its great potential for future applications in power and optoelectronic devices. However, the critical issue of contacts between metal and Ga2O3 limits the performance of β-Ga2O3 devices. In this work, we have reviewed the advances on contacts of β-Ga2O3 MOSFETs. For improving contact properties, four main approaches are summarized and analyzed in details, including pre-treatment, post-treatment, multilayer metal electrode, and introducing an interlayer. By comparison, the latter two methods are being studied intensively and more favorable than the pre-treatment which would inevitably generate uncontrollable damages. Finally, conclusions and future perspectives for improving Ohmic contacts further are presented.

Investigation of Energy Band at Atomic-Layer-Deposited ZnO/β-Ga2O3 ( 2 ¯ 01 $$ \overline{2}01 $$ ) Heterojunctions

“…However, limitations still exist in β-Ga 2 O 3 -based devices, such as the poor ohmic contact between the metal and β-Ga 2 O 3 [9]. In recent year, inserting a high electron concentration metal-oxide-semiconductor interlayer, i.e., intermediate semiconductor layer (ISL) between the metal and Ga 2 O 3 , has been shown to be an effective resolution because the modulation of energy barrier at the interface [10–12].…”

Highly Porous and Ultra-Lightweight Aero-Ga2O3: Enhancement of Photocatalytic Activity by Noble Metals

“…According to previously published data, the work function of Au was estimated to be of 5.2–5.3 eV [ 63 , 64 ], while the reported value for Pt was in the range of 5.6–5.9 eV [ 3 , 64 ]. A value of 4.0 eV was reported for the electron affinity of Ga 2 O 3 leading to the formation of a Schottky barrier height of 1.2 eV at the Au/Ga 2 O 3 interface according to the Schottky–Mott rule [ 3 , 5 , 63 , 65 ]: where Φ B is the barrier height, Φ Au is the Au work function, and χ is the electron affinity of β-Ga 2 O 3 .…”

“…β-polymorph Ga 2 O 3 has attracted most of the attention due to its superior chemical and thermal stability, wide bandgap, high stability to breakdown voltage, and high Baliga’s figure of merit (BFOM). It has been widely studied and utilized for various applications including in power electronics, solar blind UV photodetectors, solar cells, and as gas-sensing materials [ 3 , 4 , 5 ]. Photocatalysis is another emerging application of the β-Ga 2 O 3 polymorph.…”

Control and understanding of metal contacts to β-Ga2O3 single crystals: a review

“…Studies on metal contacts are essential to understand the electrical behavior of β-Ga 2 O 3 -based devices and the material properties of Ga 2 O 3 . To data, reviews of metal contacts to β-Ga 2 O 3 single crystals are still lacking [191,192]. This review suggests the following further research for metal/ β-Ga 2 O 3 contacts: (1) clarifying the correlation between various defects and current transport mechanisms based on the temperature-dependent electrical properties, (2) nanoscale electrical investigation to explain the macroscale electrical properties, (3) controllable n-type heavy doping and thermally stable metallization for ohmic contacts.…”