Effects of Electrical Characteristics on Undoped and Li-Doped NiO Interlayers Embedded Ni/β-Ga₂O₃ Schottky Barrier Diodes

Recently, beta gallium oxide (β-Ga₂O₃, 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]. Since breakdown fields are more than 8MV/cm and more than three times larger than SiC and GaN, research is actively as next-generation power semiconductors are expected to implement high breakdown voltage and low-resistance[2]. Several devices structures, such as Schottky barrier diodes (SBD), Metal-semiconductor field-effect transistor (MESFET), and metal-oxide-semiconductor field-effect transistor (MOSFET) have been studied as power devices in recent years. High breakdown voltages have been achieved in β-Ga₂O₃ SBDs, but most of which had a relatively high leakage current density at reverse bias [3]. As a strategy to complement this, other p-type oxide semiconductors (NiO_x, Cu₂O, Ir₂O₃, SnO) were used to form a pn heterojunction with n-type β-Ga₂O₃.<br/>In this study, we consider NiO_x interlayer, which has a wide bandgap of 3.6eV and is a material with p-type conductivity [4]. By inserting p-type NiO_x between β-Ga₂O₃ and Ni Schottky junction, we confirmed that the expansion of the depletion layer by securing p-n characteristics. In addition, the conductivity control of nickel oxide was attempted by lithium doping. Nickel oxide and lithium-doped nickel oxide thin films were manufactured by RF sputtering. It was intended to enhance the characteristics of the diode by lithium doping and oxygen concentration control. As a result, we expect that the p-type conductivity of a device manufactured from lithium-doped NiO_x embedded β-Ga₂O₃ SBDs give an effective approach for the reduction of reverse leakage current.<br/><b>Acknowledgements</b><br/>This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2020R1A2C1013693), Korea Institute for Advancement of Technology (KIAT) grant funded by By the Ministry of Trade, Industry & Energy (MOTIE, Korea) (P0012451, The Competency Development Program for Industry Specialist) and the Technology Innovation Program - (20016102, Development of 1.2kV Gallium oxide power semiconductor devices technology) funded by MOTIE.<br/>References<br/>[1] M. Higashiwaki and G. H. Jessen, “Guest editorial: The dawn of gallium oxide microelectronics,” Appl. Phys. Lett. 112, 060401 (2018)<br/>[2] J. Yang, S. Ahn, F. Ren, S. J. Pearton, S. Jang, J. Kim, and A. Kuramata, “High reverse breakdown voltage Schottky rectifiers without edge termination on Ga₂O₃,” Appl. Phys. Lett. 110, 192101 (2017)<br/>[3] M. Labed, S. S. Kyoung, and Y. S. Rim, “Leakage current modelling and optimization of β-Ga₂O₃ Schottky barrier diode with Ni contact under high reverse voltage,” ECS J. Solid State Sci. Technol. 9, 125001 (2020)<br/>[4] H. H. Gong, X. H. Chen, Y. Xu, F.-F. Ren, S. L. Gu, and J. D. Ye “A 1.86-kV double-layered NiO/β-Ga₂O₃ vertical p–n heterojunction diode,” Appl. Phys. Lett. 117, 022104 (2020)