Method to Predict and Optimize Charge Sensitivity of Ungated AlGaN/GaN HEMT-Based Ion Sensor Without Use of Reference Electrode

Abstract

In this paper, we report on a methodology for theoretical prediction and optimization of charge sensitivity for ungated AlGaN/GaN high electron mobility transistorbased ion sensors operated in the reference electrode free configuration. We have performed numerical simulations of device sensitivity, specifically the change in channel electron concentration with the change in surface potential, for different Al mole fractions and AlGaN thicknesses. These results can be used for device optimization, signal analysis, and sensor calibration purposes. To validate the model, six ungated AlGaN/GaN transistor-based devices of different Al mole fractions and AlGaN thicknesses were fabricated. These devices were exposed to KOH solutions with different pH values, and the voltage change at the gate area was indirectly measured as a function of ionic concentration. The gain in conductivity across the measured range of pH values was experimentally extracted for each device and closely matched the sensitivity predicted by simulation.

AlGaN/GaN high electron mobility transistor for various sensing applications: A review

“…The methods to predict and consequent optimization of charge sensitivity for ungated AlGaN/GaN HEMT was reported in [135], [136]. The numerical simulations are performed and validated with different barrier layer composition fabricated devices.…”

Performance analysis of high-k materials as stern layer in ion-sensitive field effect transistor using commercial TCAD

“…As the SiO2 gate dielectric shows a low response sensitivity and poor stability, other inorganic materials such as Al2O3 [7,8], Si3N4 [6,9], Ta2O5 [9][10][11], HfO2 [12][13][14][15] and ZrO2 [12][13][14] with their enhanced stability and sensitivity have also been investigated. The pervious works of using high-k materials as an ISFETs gate used numerical or mathematical modeling simulations [16][17][18][19]. However, now that the ISFET has become the mainstream device of a few CMOS-based sensing platforms, accurate and versatile numerical device simulations in an integrated TCAD environment are desirable to support the ISFET design, extract the ISFET equivalent circuit parameters, and perform mixed device-circuit analysis.…”

Temperature-dependent stress in diamond-coated AlGaN/GaN heterostructures

“…AlGaN/GaN high electron mobility transistors (HEMTs) [1] are attractive for a variety of sensor applications [2,3], especially, they are capable to be operated at high temperatures and in harsh environments. However, any high power application needs an efficient thermal management to suppress the self-heating of the HEMT active channel which limits their performance [4,5].…”