Effect of Embedded Pd Microstructures on the Flat-Band-Voltage Operation of Room Temperature ZnO-Based Liquid Petroleum Gas Sensors

Sensors

Ghusoon M. Ali²  Cody V. Thompson²  Ali K. Jasim¹  Isam M. Abdulbaqi¹ 

[1] Department of Electrical Engineering, Al-Mustansiriyah University, Baghdad 10052, Iraq; E-Mails:;Department of Chemistry and Physics, Coastal Carolina University, Conway, SC 29528, USA; E-Mail:

关键词: zinc oxide;    ZnO;    interdigitated;    liquid petroleum gas;    LPG;    sol-gel;    metal-semiconductor-metal;    gas sensor;    palladium;    Pd;   

DOI  :  10.3390/s131216801

来源: mdpi

【 摘 要 】

Three methods were used to fabricate ZnO-based room temperature liquid petroleum gas (LPG) sensors having interdigitated metal-semiconductor-metal (MSM) structures. Specifically, devices with Pd Schottky contacts were fabricated with: (1) un-doped ZnO active layers; (2) Pd-doped ZnO active layers; and (3) un-doped ZnO layers on top of Pd microstructure arrays. All ZnO films were grown on p-type Si(111) substrates by the sol-gel method. For devices incorporating a microstructure array, Pd islands were first grown on the substrate by thermal evaporation using a 100 μm mesh shadow mask. We have estimated the sensitivity of the sensors for applied voltage from –5 to 5 V in air ambient, as well as with exposure to LPG in concentrations from 500 to 3,500 ppm at room temperature (300 K). The current-voltage characteristics were studied and parameters such as leakage current, barrier height, reach-through voltage, and flat-band voltage were extracted. We include contributions due to the barrier height dependence on the electric field and tunneling through the barrier for the studied MSM devices. The Pd-enhanced devices demonstrated a maximum gas response at flat-band voltages. The study also revealed that active layers consisting of Pd microstructure embedded ZnO films resulted in devices exhibiting greater gas-response as compared to those using Pd-doped ZnO thin films or un-doped active layers.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.