Apr 24, 2024
5:00pm - 7:00pm
Flex Hall C, Level 2, Summit
You Seung Rim1,Jiyoung Min1,Madani Labed1,Hyungseok Kim2,Kyungwho Choi3,Teakjib Choi1
Sejong University1,Korea Institute of Science and Technology2,Sungkyunkwan University3
You Seung Rim1,Jiyoung Min1,Madani Labed1,Hyungseok Kim2,Kyungwho Choi3,Teakjib Choi1
Sejong University1,Korea Institute of Science and Technology2,Sungkyunkwan University3
Recently, beta gallium oxide (β-Ga<sub>2</sub>O<sub>3</sub>, 4.7–4.9eV), which has a wide band gap than SiC and GaN, has been attracting attentions in the field of power electronic applications [1]. The Baliga’s figure of merit(B-FOM) of Ga<sub>2</sub>O<sub>3</sub> is about 3000, which is 4 times that of GaN and 10 times that of SiC, and is expected to achieving high breakdown voltage at low on-resistance in the power device [2]. However, despite these high numbers, the actual reported performance of the power unit is much lower than expected. This is because it is difficult to implement p-type Ga<sub>2</sub>O<sub>3</sub>, which can be used as PN junction termination to improve breakdown voltage value [3]. For further improvement of devices which require lower on-resistance(R<sub>on</sub>) and higher breakdown voltage, it is important to form a junction termination structure such as a guard ring and a merged structure using a p-type material even to reduce the maximum electric field of a wide bandgap materials. However, the development of p-type β-Ga<sub>2</sub>O<sub>3</sub> remains insufficient, only the theoretical studies and few experimental results reported. Because a very low mobility of self-trap holes and a deep acceptor level are expected, p-type β-Ga<sub>2</sub>O<sub>3</sub> may intrinsically not be practical for power device applications. As a strategy to compensate for this is to construct p–n heterojunctions by integrating n-type Ga<sub>2</sub>O<sub>3</sub> with other p-type semiconductors if the interface quality is controlled in an appropriate manner [4].<br/>In this study, a diode to form a p-n heterojunction with optimized β-Ga<sub>2</sub>O<sub>3</sub> was fabricated using NiO, a material with p-type conductivity [5]. Among p-type oxide families, the wide-bandgap NiO material has promising potentials in the applications of various optoelectronic and power devices due to its high visible spectral transparency and p-type conductivity stemming from nickel vacancies or monovalent impurities [6].<br/>It was confirmed that the p-type NiO was inserted between the β-Ga<sub>2</sub>O<sub>3</sub> and the Ni Schottky junction to ensure the p-n characteristics and thus the depletion layer expanded. In addition, the conductivity control of nickel oxide was attempted by lithium doping and oxygen concentration regulation. As a result, lithium-doped nickel oxide exhibited improved ohmic contact properties with Ni due to the thin film's low specific resistance characteristics compared to undoped nickel oxide, which induced the diode's low on-resistance. Therefore, using these current characteristics, NiO was stacked in two layers to design a heterojunction diode with a Li-NiO/NiO/β-Ga<sub>2</sub>O<sub>3</sub> structure and a device that achieves a high breakdown voltage of -1678 V while maintaining a low on-resistance of 7.1 mΩcm<sup>2</sup><br/><br/><b>Acknowledgments</b> This work was supported by Korea Institute for Advancement of Technology (KIAT) grant funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea) (P0012451, The Competency Development Program for Industry Specialist), the Technology Innovation Program - (20016102, Development of 1.2kV Gallium oxide power semiconductor devices technology and RS-2022-00144027, Development of 1.2kV-class low-loss gallium oxide transistor) funded by MOTIE, and Hyundai Motor Group.<br/><br/><b>References </b>[1] M. Higashiwaki and G. H. Jessen, Appl. Phys. Lett. 112, 060401 (2018) [2] S. J. Pearton, F. Ren, M. Tadjer, and J. Kim, J. Appl. Phys. 124, 220901 (2018) [3] N. Allen, M. Xiao, X. D. Yan, IEEE Electron Device Lett. 40, 1399 (2019) [4] Y. Kokubun, S. Kubo, and S. Nakagomi, Appl. Phys. Express 9, 091101 (2016) [5] H. H. Gong, Appl. Phys. Lett. 117, 022104 (2020) [6] M. Tyagi, M. Tomar, V. Gupta, IEEE Electron Device Lett. 34, 81 (2013)