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URN etd-0516102-233902
Author Jung-Lung Chiang
Author's Email Address No Public.
Statistics This thesis had been viewed 5339 times. Download 2537 times.
Department Electrical Engineering
Year 2001
Semester 2
Degree Ph.D.
Type of Document
Language English
Title Study on the pH-Sensing Characteristics of ISFET with Aluminum Nitride Membrane
Date of Defense 2002-04-26
Page Count 112
Keyword
  • Hysteresis
  • Aluminum Nitride
  • Temperature effect
  • Sensitivity
  • Drift
  • ISFET
  • Abstract In this thesis, the aluminum nitride (AlN) thin film was selected as a sensing membrane for the H+ ion-sensitive field-effect transistor (ISFET). The AlN thin films were prepared by a rf sputtering technology on the reference electrode/electrolyte /AlN /SiO2/p-Si/Al structure. The capacitance-voltage (C-V) measurement was used to detect the H+ ion concentration and the C-V characteristic curves were obtained in the different pH buffer solutions. On the other hand, AlN thin films were also prepared on the double layer structure of AlN/SiO2 gate ISFET devices. After packaging, the current-voltage (I-V) measurement with a PID temperature controller was utilized to measure a series of the I-V characteristic curves. The threshold voltage can be obtained to evaluate the pH sensitivity in the different pH buffer solutions. Additionally, the effects of non-ideal factors, such as temperature effect, drift and hysteresis phenomenon on the characteristics of the ISFET are also measured, analyzed and compared with other sensing materials.
    According to the experimental results, it can be found that the ISFET based on aluminum nitride thin film has a superior high pH sensitivity of approximately 50~58 mV/pH at 25℃. The drift and hysteresis are dependent on the H+ ion concentration in pH=1~11, in which the drift rate increases with the pH value increased and the hysteresis magnitude depends on the measuring time and route. It is found that the hysteresis widths measured in pH=7®3®7®11®7 cycle at 960s, 1920s and 3840s loop time are 1.0, 1.5 and 4.5 mV, respectively. When the temperature effect was considered, it was found that the ISFET could be operated at 5~65℃, in which, the pH sensitivity increased as the ambient temperature increased with the temperature coefficient of sensitivity of about 0.13 mV/pH℃. In addition, the output voltage of AlN pH-ISFET can be obtained by a constant current constant voltage (CCCV) read out circuit with a fairly linear response, stability and reproducibility in the pH measuring cycle. From the characteristics mentioned above, the AlN thin film can be as a sensing membrane for pH-ISFET applications.
    Advisory Committee
  • Yeong-Her Wang - chair
  • Tai-Ping Sun - co-chair
  • none - co-chair
  • Mau-Phon Houng - co-chair
  • none - co-chair
  • Jung-Chuan Chou - advisor
  • Ying-Chung Chen - advisor
  • Files
  • etd-0516102-233902.pdf
  • indicate accessible in a year
    Date of Submission 2002-05-16

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