The Electrical and pH-Sensitive Characteristics of Thermal Gd[sub 2]O[sub 3]∕SiO[sub 2]-Stacked Oxide Capacitors

Abstract

The Gd 2 O 3 /SiO 2 -stacked oxides prepared by thermal oxidation were implemented at 1000°C for 5-30 min in ambient oxygen. The transmission electron microscopy results indicated that the longer the oxidation time the thicker the oxide layer. Meanwhile the grown layer surface roughness is reduced and the hysteresis of the corresponding metal oxide semiconductor capacitor is decreased. Large shifts of flatband voltages are observed when the stacks' layer ͑Gd 2 O 3 /SiO 2 ͒ electrolyte-insulator-semiconductor structure is immersed in the pH 2, 4, 6, 8, and 10 buffer solutions, respectively. The hydrogen ion sensitivity of this structure is found to be 53.31 mV/pH.

Structural properties and sensing performance of high-k Nd2TiO5 thin layer-based electrolyte–insulator–semiconductor for pH detection and urea biosensing

“…However, pH-ISFET devices based on Si 3 N 4 sensing membrane normally show unstable properties on threshold voltage stemming from the conversion of silicon nitride film to a hydrated silicon dioxide (SiO 2 ) or an oxynitride layer during the contact with an aqueous solution (Jamasb et al, 1998a,b). In order to solve this problem, several high dielectric constant (high-k) materials, including Al 2 O 3 , Ta 2 O 5 , ZrO 2 , HfO 2 , Y 2 O 3 , Gd 2 O 3 and Pr 2 O 3 were recently proposed as a pH sensing membrane borrowing from their good sensing performance and highly thermal stability, as demonstrated in the literature (Bousse et al, 1990;Kwon et al, 1996;Yoshida et al, 2004;Lai et al, 2006;Liao, 2007, 2008;Chang et al, 2006). Nevertheless, the poor interface existing in between the metal oxide and Si substrate (Wilk et al, 2001) remains a technical hurdle to overcome.…”

Structural properties and sensing characteristics of Y2O3 sensing membrane for pH-ISFET

“…Recently, high dielectric constant (high k) materials, such as Al 2 O 3 , Ta 2 O 5 , TiO 2 , WO 3 , and ZrO 2 [4][5][6][7][8] were proposed as hydrogen ion sensing membrane for pH-ISFET to replace Si 3 N 4 membrane because of their high sensitivity performance. In addition, HfO 2 and Gd 2 O 3 layers with good sensing performance and high thermal stability were proposed for electrolyte-insulator semiconductor (EIS) structure [9,10]. However, because of the poor interface between the high k material and silicon substrate, all sensing membranes must be deposited on the thermally grown SiO 2 to improve the * Corresponding author.…”

A urea biosensor based on pH-sensitive Sm2TiO5 electrolyte–insulator–semiconductor

“…To extend the application of pH-ISFET sensors, it will be necessary to develop insulator materials that possess high pH sensitivity, small hysteresis, high stability, and low drift. High-dielectric-constant (high-k) materials, including ZrO 2 , HfO 2 , Y 2 O 3 , Pr 2 O 3 , Gd 2 O 3 , and Er 2 O 3 [8][9][10][11][12][13], have recently been proposed as pH-sensitive membranes due to their good sensing performance in electrolyte-insulator-semiconductor (EIS) devices. To improve the quality of the interface between the high-k material and the silicon substrate, growing a thin SiO 2 film on the Si substrate imparts the pH sensing membrane with a smaller density of the interfacial state, lower stress, and good adhesion [14].…”