Po Cheng Chou

ZnO-Nanorod-Based Ammonia Gas Sensors With Underlying Pt/Cr Interdigitated Electrodes

ZnO-nanorod-based resistor-type ammonia gas sensors with underlying Pt/Cr interdigitated electrodes have been fabricated and investigated. The response is improved by reducing the electrode spacing d. Experimentally, a high response of 80.6 is found when d is reduced to 2 μm under exposure to a 1000-ppm NH3 /air gas at 300 °C. A lower detection limit of 10-ppm NH3/air at 300 °C is also obtained. This device possesses response and recovery times of <; 3 min even at low ammonia concentrations (10 ppm). The enhanced ammonia-sensing capability with reducing electrode spacing d could be attributed to the formation of more ZnO grain boundaries. A simple cross-linked structure model is presented to interpret the ammonia-gas-sensing performance, and a good correlation between theory and experiment is demonstrated.

On an Ammonia Gas Sensor Based on a Pt/AlGaN Heterostructure Field-Effect Transistor

A new and interesting Pt/AlGaN heterostructure field-effect transistor (HFET)-based ammonia gas sensor is fabricated and investigated. The related ammonia-sensing mechanisms, including direct dissociation of ammonia gas and triple-point model, are presented. Experimentally, the maximum transconductance variation Δgm and threshold voltage variation ΔVth are 16.63 mS/mm and 318.1 mV, respectively, upon exposing to a 10 000-ppm NH3/air gas. In addition, the maximum sensing response and rectification ratio of 113.4 and 2.1 × 103, respectively, are obtained when 10 000- and 35-ppm NH3/air gases are introduced. Therefore, the studied Pt/AlGaN HFET shows the promise for ammonia-gas-sensing applications.

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

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<formula formulatype=inline><tex Notation=TeX>

Effects of the Use of an Aluminum Reflecting and an

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Insulating Layers (RIL) on the Performance of a GaN-Based Light-Emitting Diode With the Naturally Textured p-GaN Surface

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On a GaN-Based Light-Emitting Diode With an Aluminum Metal Mirror Deposited on Naturally-Textured V-Shaped Pits Grown on the p-GaN Surface

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Implementation of High-Power GaN-Based LEDs With a Textured 3-D Backside Reflector Formed by Inserting a Self-Assembled

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