Jun-Long Su

Bio: Jun-Long Su is an academic researcher from National Cheng Kung University. The author has contributed to research in topics: Electron mobility & Transconductance. The author has an hindex of 1, co-authored 1 publications receiving 12 citations.

Comparison of Al0.32Ga0.68N ∕ GaN Heterostructure Field-Effect Transistors with Different Channel Thicknesses

Abstract: Al 0. 32 Ga 0. 68 N/GaN heterostructure field-effect transistors (HFETs) grown by low-pressure metallorganic chemical vapor deposition are successfully fabricated. A Mg-doped insulating GaN layer is inserted to suppress the leakage current, improve the breakdown voltages, and yield excellent pinch-off characteristics. Moreover, HFETs with different channel thicknesses of 1200, 1500, and 1800 A are investigated. Experimental results show that an HFET with a 1800 A thick channel layer has the highest electron mobility, electron concentration, drain current, and extrinsic transconductance.

Ammonia sensing characteristics of a Pt/AlGaN/GaN Schottky diode

Abstract: The interesting ammonia sensing current–voltage ( I–V ) characteristics of a Pt/AlGaN/GaN Schottky diode are firstly studied and demonstrated. It is found that the ammonia sensitivity is increased by increasing the temperature. Yet, the sensitivity is decreased when the temperature is higher than 423 K. Experimentally, the studied device exhibits a good sensitivity of 13.1 under exposing to a relatively low concentration ammonia gas of 35 ppm NH 3 /air. In addition, the good sensing performance of the studied device is demonstrated over a wide operating temperature regime from 298 K to 473 K. A highest ammonia sensing response of 182.7 is found at 423 K while a 10,000 ppm NH 3 /air gas is introduced.

Improved AlGaN/GaN Metal–Oxide– Semiconductor High-Electron Mobility Transistors With TiO 2 Gate Dielectric Annealed in Nitrogen

Abstract: An AlGaN/GaN metal–oxide–semiconductor high-electron mobility transistor (MOS-HEMT) that uses a high-k TiO2 gate insulator is demonstrated. TiO2 films are annealed at 300 °C and 600 °C in N2 or O2 following the deposition of an oxide layer. Experimental results reveal that the 300 °C N2-annealed TiO2/GaN MOS capacitor has the smallest interface traps of any of the studied devices. The 300 °C N2-annealed oxide interlayers between the GaN and the gate metal reduce the gate leakage current and improve the dc, high-frequency, and noise characteristics. The gate leakage current of the 300 °C N2-annealed MOS-HEMT is more than 3 orders of magnitude less than that of the baseline HEMT. This brief is the first to fabricate a GaN-based MOS-HEMT using an N2-annealed TiO2 gate insulator.

Ammonia Sensing Properties of a Pt/AlGaN/GaN Schottky Diode

Abstract: An interesting Pt/AlGaN/GaN Schottky-type ammonia gas sensor is fabricated and studied. Both the steady-and transient-state behaviors of ammonia adsorption reactions are investigated. At 150°C, significant ammonia detection is observed under a low ammonia concentration of 35-ppm NH3/air. Moreover, a high ammonia sensing response of 18300% and the large Schottky barrier variation ratio A.φb/φb, air of 13.8% are observed upon exposure to a 1% NH3/air gas at 150°C. The presence of dipoles at the metal-semiconductor interface leads to a lowering effect of Schottky barrier height and a larger current. In addition, based on thermodynamics, in contrast with a hydrogen adsorption reaction, the ammonia adsorption reaction is an endothermic reaction. Consequently, the studied NH3 sensor structure provides the promise to integrate high-performance AlGaN/ GaN-based optoelectronic and microwave devices on a single chip.

Hydrogen-Sensing Properties of a Pd/AlGaN/GaN-Based Field-Effect Transistor Under a Nitrogen Ambience

Abstract: The hydrogen-sensing characteristics of a Pd/AlGaN/GaN heterostructure field-effect transistor (HFET) under a nitrogen ambience are studied in this paper. Good and stable hydrogen-sensing behaviors are obtained over the operating temperature from 30 $^{\circ}{\rm C}$ to 250 $^{\circ}{\rm C}$ . In addition, HFET shows the significant hydrogen-detecting ability under an extremely low hydrogen concentration of 10-ppb ${\rm H}_{2}/{\rm N}_{2}$ . Good transient responses are also observed even at room temperature. In addition, a small and nearly constant value of recovery time $({\approx}{\rm 20}~{\rm s})$ is acquired when the hydrogen concentration is higher than 1-ppm ${\rm H}_{2}/{\rm N}_{2}$ at room temperature. Therefore, the studied device shows a promise for high-performance, high-temperature electronics, microsensors, and microelectromechanical system applications.