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Review
. 2018 Aug 22;13(1):246.
doi: 10.1186/s11671-018-2667-2.

Recent Advances in β-Ga2O3-Metal Contacts

Ya-Wei Huan  1 , Shun-Ming Sun  1 , Chen-Jie Gu  2 , Wen-Jun Liu  3 , Shi-Jin Ding  4 , Hong-Yu Yu  5 , Chang-Tai Xia  6 , David Wei Zhang  1
Affiliations
Review

Recent Advances in β-Ga2O3-Metal Contacts

Ya-Wei Huan et al. Nanoscale Res Lett. .

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.

Keywords: Contacts; Intermediate semiconductor layer; Metal stacks; β-Ga2O3.

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The authors declare that they have no competing interests.

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Figures

Fig. 1
Fig. 1
Schematic illustrations of a Ohmic contacts and b Schottky contacts. EC, EV, EF, m, and EF, s are the energy levels of the conduction band edge, valence band edge, Fermi energy of metal and semiconductor, respectively
Fig. 2
Fig. 2
The energy band diagram at the metal/semiconductor interface with highly doped semiconductors
Fig. 3
Fig. 3
(Color online) I–V curves measured between two contacts (as-deposited Ti/Au) fabricated with and without RIE treatment on n-Ga2O3 substrates. Reproduced from Ref. [1]
Fig. 4
Fig. 4
(Color online) DC output characteristics of Ga2O3 metal/semiconductor field-effect transistors. Reproduced from Ref. [1]
Fig. 5
Fig. 5
DC I–V curves of Ga2O3 MOSFET (Lg = 2 μm) measured at RT. Reproduced from Ref. [12]
Fig. 6
Fig. 6
Output characteristics of the SOG S/D-doped MOSFET with Lg = 8 μm, drain gate spacing Lgd = 10 μm. Reproduced from Ref. [53]
Fig. 7
Fig. 7
Electrical properties of β-Ga2O3 flakes with different thermal annealing atmosphere and annealing temperature. Ti/Au contacts under a N2 and b air. Reproduced from Ref. [55]
Fig. 8
Fig. 8
Atomic percentage profiles by EDS of metallization and β-Ga2O3 a pre- and b post-annealing at a temperature of 500 °C. Reproduced from Ref. [55]
Fig. 9
Fig. 9
I–V plots for Ti/Au contacts on Sn-doped (2¯01) Ga2O3 wafer as a function of annealing temperature in Ar (annealing time 1 min). Reproduced from Ref. [56]
Fig. 10
Fig. 10
The schematic of metal stacks for obtaining Ohmic contacts to wide-bandgap semiconductors
Fig. 11
Fig. 11
The schematic of band offsets for a metal/β-Ga2O3 and b metal/ISL/β-Ga2O3. ∆Ec equals the energy difference between the Fermi energy of metals and the conduction band of semiconductors
See this image and copyright information in PMC

References

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