PMID- 22163786
OWN - NLM
STAT- MEDLINE
DCOM- 20120605
LR  - 20211021
IS  - 1424-8220 (Electronic)
IS  - 1424-8220 (Linking)
VI  - 11
IP  - 3
DP  - 2011
TI  - Open-gated pH sensor fabricated on an undoped-AlGaN/GaN HEMT structure.
PG  - 3067-77
LID - 10.3390/s110303067 [doi]
AB  - The sensing responses in aqueous solution of an open-gated pH sensor fabricated 
      on an AlGaN/GaN high-electron-mobility-transistor (HEMT) structure are 
      investigated. Under air-exposed ambient conditions, the open-gated undoped 
      AlGaN/GaN HEMT only shows the presence of a linear current region. This seems to 
      show that very low Fermi level pinning by surface states exists in the undoped 
      AlGaN/GaN sample. In aqueous solution, typical current-voltage (I-V) 
      characteristics with reasonably good gate controllability are observed, showing 
      that the potential of the AlGaN surface at the open-gated area is effectively 
      controlled via aqueous solution by the Ag/AgCl gate electrode. The open-gated 
      undoped AlGaN/GaN HEMT structure is capable of distinguishing pH level in aqueous 
      electrolytes and exhibits linear sensitivity, where high sensitivity of 1.9 mA/pH 
      or 3.88 mA/mm/pH at drain-source voltage, V(DS) = 5 V is obtained. Due to the 
      large leakage current where it increases with the negative gate voltage, 
      Nernstian like sensitivity cannot be determined as commonly reported in the 
      literature. This large leakage current may be caused by the technical factors 
      rather than any characteristics of the devices. Surprisingly, although there are 
      some imperfections in the device preparation and measurement, the fabricated 
      devices work very well in distinguishing the pH levels. Suppression of current 
      leakage by improving the device preparation is likely needed to improve the 
      device performance. The fabricated device is expected to be suitable for pH 
      sensing applications.
FAU - Abidin, Mastura Shafinaz Zainal
AU  - Abidin MS
AD  - Material Innovations and Nanoelectronics Research Group, Faculty of Electrical 
      Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. 
      mastura@fke.utm.my
FAU - Hashim, Abdul Manaf
AU  - Hashim AM
FAU - Sharifabad, Maneea Eizadi
AU  - Sharifabad ME
FAU - Rahman, Shaharin Fadzli Abd
AU  - Rahman SF
FAU - Sadoh, Taizoh
AU  - Sadoh T
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20110309
PL  - Switzerland
TA  - Sensors (Basel)
JT  - Sensors (Basel, Switzerland)
JID - 101204366
RN  - 0 (Aluminum Compounds)
RN  - 0 (aluminum gallium nitride)
RN  - CH46OC8YV4 (Gallium)
RN  - VRA0C6810N (gallium nitrate)
SB  - IM
MH  - Aluminum Compounds/*chemistry
MH  - Electrochemical Techniques/*instrumentation/*methods
MH  - *Electrons
MH  - Gallium/*chemistry
MH  - Hydrogen-Ion Concentration
MH  - *Transistors, Electronic
PMC - PMC3231593
OTO - NOTNLM
OT  - AlGaN/GaN
OT  - HEMT
OT  - liquid-pHase
OT  - open-gated structure
OT  - pH sensor
EDAT- 2011/12/14 06:00
MHDA- 2012/06/06 06:00
PMCR- 2011/01/01
CRDT- 2011/12/14 06:00
PHST- 2011/01/10 00:00 [received]
PHST- 2011/02/28 00:00 [revised]
PHST- 2011/03/07 00:00 [accepted]
PHST- 2011/12/14 06:00 [entrez]
PHST- 2011/12/14 06:00 [pubmed]
PHST- 2012/06/06 06:00 [medline]
PHST- 2011/01/01 00:00 [pmc-release]
AID - s110303067 [pii]
AID - sensors-11-03067 [pii]
AID - 10.3390/s110303067 [doi]
PST - ppublish
SO  - Sensors (Basel). 2011;11(3):3067-77. doi: 10.3390/s110303067. Epub 2011 Mar 9.