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

Abstract

Gallium oxide (Ga2O3) is a promising semiconductor for high power devices and solar blind ultraviolet photodetectors due to its large bandgap, a high breakdown field, and high thermal stability. Recently, a considerable achievement has been obtained for the growth of high-quality β-Ga2O3 and high performance β-Ga2O3 based devices. However, rapid advance in device performance can be limited by the critical issues of metal contacts to β-Ga2O3 such as barrier height, leakage current, ohmic contact, and surface, interfacial and deep states. This article aims to provide a review on the recent studies in the control and understanding of metal contacts to β-Ga2O3, particularly in terms of the barrier formation. This review suggests that understanding the current transport mechanisms of metal contacts to β-Ga2O3 more thoroughly is necessary to enhance the performance, stability and reliability of β-Ga2O3 based devices.

Nontrivial role of polar optical phonons in limiting electron mobility of two-dimensional Ga2O3 from first-principles

“…Similar to bulk Ga 2 O 3 , the implementation of p-type conductivity is still tricky. 3,44 It demonstrates that p-type 2D Ga 2 O 3 devices are almost impossible to be applied. Therefore, we only focus on electron mobility.…”

High Performance of Zero-Power-Consumption MOCVD-Grown β-Ga2O3-Based Solar-Blind Photodetectors with Ultralow Dark Current and High-Temperature Functionalities

“…At RT, SBH of 1 and 0.66 eV and an ideality factor of unity were obtained under dark and UV illumination conditions, respectively. However, SBH increased with increasing temperature under dark and UV illumination conditions, which indicated spatial barrier inhomogeneity at the Ni/β-Ga 2 O 3 interface. , Also, the ideality factor remained at unity over the whole temperature range under both dark and UV illumination conditions, indicating the high-quality Schottky contact and absence of any thin oxide layer. The SBH increased from 1 to 1.31 eV in dark conditions and from 0.66 to 0.93 eV under UV illumination conditions on increasing temperature from RT to 125 °C.…”

Gallium Oxide for Gas Sensor Applications: A Comprehensive Review

“…They possess advantages such as simple configuration, easy fabrication, and cost effectiveness and can be easily miniaturized and integrated on a microelectronic mechanical system platform. A typical resistor-type gas sensor based on Ga 2 O 3 is depicted in Figure 9 a. Pt and Au are commonly used as measuring electrodes, since the electron affinity of Ga 2 O 3 is as large as about 4 eV [ 40 ]. Similar to solar-blind ultraviolet photodetectors, the interdigitated electrode geometry, which enables a wide contact area, is the most widely accepted geometry for a resistor sensor.…”

“…A variety of electronic and optoelectronic devices such as Schottky barrier diodes (SBDs) [ 5 , 6 ] and FETs, including MESFETs, MOSFETs, MODFETs, and HEMTs [ 6 , 7 , 8 , 9 ] based on Ga 2 O 3 bulk single crystals, thin films, and nanostructured materials, have been achieved thanks to the advance in growth and characterization technologies and the unique properties of Ga 2 O 3 . There have been tens of review articles [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ] concerning Ga 2 O 3 that cover the growth techniques, the physical and chemical properties, and the state-of-the-art device fabrications. Although initial studies on the gas-sensing properties of Ga 2 O 3 thin films were launched by Fleischer and Meixner [ 41 , 42 ] in the early 1990s, few review papers on Ga 2 O 3 -based gas sensors exist in the literature.…”