People

Dr. Yeong-Her Wang, Distinguished Professor of the Department of Electrical Engineering at National Cheng Kung University- Failure is a Stepping Stone to Success. [ 下載 PDF ]

Claire Lin

Compound Semiconductors Driving New Materials Revolution

Special Issue Introduction of “Compound Semiconductors Driving New Materials Revolution” [ 下載 PDF ]

Ray-Hua Horng

Study on the P-type Gallium Oxide Epitaxial Films and the Applications in Power Diodes [ 下載 PDF ]

Xin-Ying Tsai, Cheng-Han Lee, Ray-Hua Horng

This study addressed the difficulty in fabricating p-type gallium oxide (Ga₂O₃). Usingphosphorus ion implantation, this research successfully developed P-type Ga₂O₃ and applied it to the fabrication of homogeneous PN diodes. Experimental results showed that after hightemperature annealing and activation, the P-doped Ga₂O₃ exhibited a positive Hall voltage, confirming its P-type semiconductor properties. The resistivity was reduced to 1.01 Ω·cm, approximately nine orders of magnitude lower than that of the undoped Ga₂O₃. A homogeneous PN Ga₂O₃ diode was fabricated using P-doped P-type Ga₂O₃ and silicon-doped N-type Ga₂O₃. To avoid the high leakage caused by silicon diffusion during the high-temperature phosphorus activation process in the P-side-up structure, this study employed an N-side-up structure and regrowth technology to effectively suppress silicon diffusion, significantly improving rectification characteristics and increasing the breakdown voltage to 979 V. Furthermore, this study fabricated a nickel oxide/gallium oxide heterojunction PN diode. Comparisons with the homogeneous diode revealed that the homogeneous diode exhibited superior reliability and stability. This research result not only confirms the feasibility of P-type phosphorus-doped gallium oxide, but also lays the foundation for the future development of high-efficiency gallium oxide power devices.　

Fabrication of β-Ga2O3 Metal-oxidesemiconductor Field-effect Transistors with δ-doped Channel via Non-vacuum Mist Chemical Vapor Deposition [ 下載 PDF ]

Hao-Chun Hung, Han-Yin Liu, Wei-Chou Hsu

This study demonstrates, for the first time, the successful integration of tin (Sn) δ-doping into the channel layer of β-Ga₂O₃ metal-oxide-semiconductor field-effect transistors (MOSFETs) using a non-vacuum mist chemical vapor deposition (Mist CVD) technique. The fabricated Sn δ-doped β-Ga₂O₃ MOSFET exhibited excellent characteristics, including a maximum drain current of 2.38 mA/mm, a threshold voltage of –8.1 V, a subthreshold swing of 394.5 mV/dec, a specific on-resistance of 1.49 Ω·cm², and an off-state breakdown voltage of 1270 V, corresponding to a power figure of merit (PFOM) of 1.08 MW/cm². Comprehensive material and electrical analyses, including XRD, SIMS, and CV measurements, confirm the successful realization of a high-quality δ-doped heteroepitaxial structure. These results highlight the potential of Mist CVD as a costeffective and scalable method for developing high-performance β-Ga₂O₃ power devices.

Investigation of Fabrication and Characteristics of GaN-based Metal-oxidesemiconductor High-electron Mobility Transistors and Integrated Circuits [ 下載 PDF ]

Ching-Ting Lee

The novel vapor cooling condensation system and the photoelectrochemical oxidation/etching systems were used to fabricate high performance depletion mode and enhancement mode gallium nitride (GaN)-based metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs). The complementary MOSHEMT integrated circuits were fabricated by monolithically integrated the depletion mode and enhancement mode devices and applied in inverter circuits. In this work, high-power and high frequency MOSHEMTs were realized by using the GaN-based semiconductors and used in logic circuits.

Exploring the Microscopic World of Materials: Building a More Sensitive Electronic Nose by First-principles Calculations [ 下載 PDF ]

Yi-Jun Guo, Guan-Yu Chen, Yan-Cheng Lin, Sheng-Yuan Jhang, Jine-Du Fu, Cheng-Lung Yu, Po-Liang Liu

With increasing attention to air quality, the development of highly sensitive sensing materials has become a key technology. To evaluate the potential of metal oxides for detecting nitrogen oxides (NO_x), this study employed first-principles calculations to investigate the work function changes of ZnO and ZnGa₂O₄ surfaces upon NO_x adsorption. The results reveal that Ag decoration significantly enhances the electron transfer capability of ZnO, leading to a 1.7-fold increase in the work function shift upon NO₂ adsorption compared to pristine ZnO. Moreover, adsorption of NO and NO₂ on the Ga-Zn-O-terminated surface of ZnGa₂O₄ induces work function changes of +4.97 eV and +1.82 eV, respectively. These findings demonstrate the exceptional sensitivity of these surfaces and provide theoretical insights for the design of high-performance gas sensors.

Exploration of Gallium Oxide-based Semiconductors for Nonenzymatic Biomedical Sensor Applications [ 下載 PDF ]

Hsin-Yu Chou, Wei-Hsiang Chiang, Yao-Chi Chang, Keng-Hung Wu, Jung-Lung Chiang, Dong-Sing Wuu

This study employed various deposition techniques to fabricate gallium oxide-based thin films on multiple substrates and integrated them into extended-gate field-effect transistor (EGFET) structures for multifunctional, nonenzymatic physiological sensing. Leveraging the films’ high stability and selective compound adsorption, the sensors achieve sensitive detection of pH, glucose, ammonia nitrogen (NH₃-N), and cell viability. Enzyme-free design reduces cost and extends storage life. Biocompatibility tests confirm noncytotoxicity, making the devices suitable for long-term biomedical monitoring. The results demonstrate gallium oxide-based semiconductors as promising materials for multifunctional biosensors in healthcare and environmental applications.

Fabrication and Engineering of Novel Quasi Two-dimensional Semiconductors [ 下載 PDF ]

Yi-Cheng Chen, Yong-Jyun Wang, Ying-Hao Chu

With the rapid advancement of modern microelectronics, silicon has long served as the core material for semiconductor devices due to its moderate bandgap, stable physical and chemical properties, and high-quality interface with its native oxide layer. However, as process node scales down to below 10 nm, silicon increasingly faces challenges such as reduced carrier mobility, shortchannel effects, and interface defects. This has driven researchers to actively seek alternative materials with superior performance and novel physical properties. Among them, quasi-twodimensional semiconductor Bi₂O₂Se has shown great potential for next-generation devices, owing to its high electron mobility, environmental stability, and ability to spontaneously form a high-k native oxide layer (Bi₂SeO₅). Bi₂O₂Se can be synthesized using various fabrication techniques, including chemical vapor deposition (CVD), molecular beam epitaxy (MBE), and pulsed laser deposition (PLD), and can be integrated into advanced transistor architectures. Furthermore, the material exhibits diverse physical properties, making it a promising candidate for applications in logic, memory, sensing, and energy devices. This article explores the development and research prospects of Bi₂O₂Se in material growth, device integration, and property engineering.

Column

High-brightness Continuous-wave Laser Systems and Technologies Toward and Beyond 100 kW [ 下載 PDF ]

Hsiao-Hua Wu

This article reviews systems and technologies with the potential to achieve—and surpass—the 100-kW class in high-brightness continuous-wave (CW) lasers. The approaches considered include spectral and coherent beam combining of fiber lasers, distributed-gain solid-state architectures, and diode-pumped alkali vapor lasers. Such 100-kW-class systems have prospective applications in defense against rockets, artillery, unmanned aerial vehicles, and missiles, as well as in industrial processing tasks such as drilling, cutting, and welding of structural panels for vehicles, ships, and aircraft. The aim is to encourage greater attention and support from government and industry for research and development on high-brightness, high-power CW lasers in Taiwan, with the goal of realizing domestically produced 100-kW-class systems in the near future. The article also seeks to catalyze further technical reporting and discourse in this field.