C. S. Ho

Enhanced AlGaN/GaN MOS-HEMT Performance by Using Hydrogen Peroxide Oxidation Technique

This paper investigates enhanced device characteristics of AlGaN/GaN metal-oxide-semiconductor high electron mobility transistor (HEMT) (MOS-HEMT) fabricated by using hydrogen peroxide (H2O2) oxidation technique which demonstrates the advantages of simplicity and cost effectiveness. A 13-nm-thick Al2O3 oxide was grown upon the surface of AlGaN barrier layer and served as the gate dielectric layer and the surface passivation layer at the same time to effectively decrease gate leakage current and prevent RF current collapse, which are the critical issues of nitride HEMTs. Enhanced device performances of dc, RF, power, and reliability of the present MOS-HEMT are comprehensively investigated as compared with a conventional Schottky-gate HEMT.

Comparative studies of AlGaN/GaN MOS-HEMTs with stacked gate dielectrics by the mixed thin film growth method

This paper reports Al0.27Ga0.73N/GaN metal–oxide–semiconductor high electron mobility transistors (MOS-HEMTs) with stacked Al2O3/HfO2 gate dielectrics by using hydrogen peroxideoxidation/sputtering techniques. The Al2O3 employed as a gate dielectric and surface passivation layer effectively suppresses the gate leakage current, improves RF drain current collapse and exhibits good thermal stability. Moreover, by stacking the good insulating high-k HfO2 dielectric further suppresses the gate leakage, enhances the dielectric breakdown field and power-added efficiency, and decreases the equivalent oxide thickness. The present MOS-HEMT design has demonstrated superior improvements of 10.1% (16.4%) in the maximum drain–source current (IDS, max), 11.4% (22.5%) in the gate voltage swing and 12.5%/14.4% (21.9%/22.3%) in the two-terminal gate–drain breakdown/turn-on voltages (BVGD/VON), and the present design also demonstrates the lowest gate leakage current and best thermal stability characteristics as compared to two reference MOS-HEMTs with a single Al2O3/(HfO2) dielectric layer of the same physical thickness.

Investigations of AlGaN/GaN HFETs utilizing post-metallization etching by nitric acid treatment

This work investigates AlGaN/GaN heterostructure field-effect transistors (HFETs) processed by using a simple post-metallization etching (PME) treatment. Decreased gate length (LG) can be achieved by using nitric acid (HNO3) PME treatment owing to the high etching selectivity of HNO3 of Ni against the Au and GaN layer. Influences on LG, etched gate profiles and device characteristics with respect to different PME processing parameters by HNO3 treatment are systematically investigated. Optimum device performance is obtained as LG was reduced to 0.5 μ mb y using a1 μm long gate mask by immersing the device into a 45% diluted HNO3 solution for 35 s. Improved device performances, including maximum drain‐source current density (IDS, max: 657.6 mA mm −1 → 898.5 mA mm −1 ), drain‐source saturation current density at zero gate bias (IDSS0: 448.3 mA mm −1 → 653.4 mA mm −1 ), maximum extrinsic transconductance (gm, max: 158.3 mS mm −1 → 219.2 mS mm −1 ), unity-gain cut-off frequency (fT: 12.35 GHz → 22.05 GHz), maximum oscillation frequency (f max: 17.55 GHz → 29.4 GHz) and power-added efficiency (P.A.E.: 26.3% → 34.5%) compared to the untreated reference device, have been successfully achieved. (Some figures may appear in colour only in the online journal)

A Device Performance Study of Stacked Gate Dielectrics AlGaN/GaN MOS-HEMTs by Mixed Oxide Thin Film Growth Techniques

This paper reports an AlGaN/GaN metal-oxidesemiconductor high electron mobility transistor (MOS-HEMT) with stacked Al2O3/HfO2 gate dielectrics by using hydrogen peroxide (H2O2) oxidation/sputtering techniques. The present Al2O3/HfO2 bi-layer MOS-HEMTs can combine the advantages of both gate dielectrics and have demonstrated enhanced drive current, breakdown, and power characteristics.

Effects of Poly(3-hexylthiophene) Concentration on Performance of Extended-Gate Field-Effect Transistor for Silver Ion Detection

The characteristics of selective silver ion sensors are developed by extended-gate field-effect transistor (EGFET) are reported. In comparison with various concentrations of P3HT, the 70 mg/ml P3HT exhibits an excellent sensitivity of 68.15 mV/decade and a linearity of 0.969 in the silver ion range of 10 -1 M to 10 -7 M. We believe that broad orientation distribution of crystalline domains, which caused more interaction between Ag+ and conjugated polymer backbone, and lead 70 mg/ml P3HT films in Ag + -EGFET have high sensitivity.

Influence of absorption property by doping/inserting C545T in Polymer Solar Cell

1 Institute of Microelectronics, Department of Electrical Engineering, and Advanced optoelectronic Technology Center, National Cheng Kung University, No. 1 University Road, Tainan, 70101, Taiwan, Republic of China Phone: +886-6-2757575#62350 E-mail: wchsu@eembox.ncku.edu.tw Department of Electronic Engineering, Feng Chia University, Taichung, Taiwan, Republic of China. Institute of Opto-Mechatronic, National Chung Cheng University, Min-Hsiung, Chia-Yi, 62145, Taiwan, Republic of China.

High Efficiency Top-Emission Organic Light-Emitting Diodes

Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, 1, University Road, Tainan, Taiwan 70101, Republic of China Phone: +886-6-2757575#62350 / E-mail: wchsu@eembox.ncku.edu.tw Department of Electronic Engineering, Feng Chia University, 100, Wenhwa Road, Taichung, Taiwan 40724, Republic of China Institute of Opto-Mechatronics, National Chung Cheng University, 168, University Road, Chia Yi, Taiwan 62145, Republic of China

Single Donor-Acceptor Heterojunction Organic Photovoltaic Cell with an AgO-Based Anode

Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University Advanced Optoelectronic Technology Center, National Cheng Kung University 1 University Road, Tainan, Taiwan 70101, R.O.C. Phone: +886-6-2757575 #62350 E-mail: wchsu@eembox.ncku.edu.tw Department of Electronic Engineering, ICEMC Center, Feng Chia University 100 Wenhwa Road, Taichung, Taiwan 40724, R.O.C.