Charging mechanism of AlGaN/GaN open-gate pH sensor and electrolyte interface

Anvari, Roozbeh; Myers, Matthew; Umana‐Membreno, Gilberto A.; Baker, Murray V.; Spagnoli, Dino; Nener, Brett

doi:10.1109/commad.2014.7038679

Cited by 5 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, as deficiency remains in precisely understanding the latent mechanism of the response so far from the viewpoint, whether for chemistry or physics, although some work has been done [24,25,26]. The site-binding model is often adopted to roughly interpret the pH-sensing process as an absorption effect of protons (H + ) or hydroxyl (OH − ) ions by the hydroxyl groups on the device sensing surface, which will form positive or negative charge sites.…”

Section: Discussionmentioning

confidence: 99%

High Sensitive pH Sensor Based on AlInN/GaN Heterostructure Transistor

Yan

Son

Dai

et al. 2018

Sensors

View full text Add to dashboard Cite

The AlInN/GaN high-electron-mobility-transistor (HEMT) indicates better performances compared with the traditional AlGaN/GaN HEMTs. The present work investigated the pH sensor functionality of an analogous HEMT AlInN/GaN device with an open gate. It was shown that the Al0.83In0.17N/GaN device demonstrates excellent pH sense functionality in aqueous solutions, exhibiting higher sensitivity (−30.83 μA/pH for AlInN/GaN and −4.6 μA/pH for AlGaN/GaN) and a faster response time, lower degradation and good stability with respect to the AlGaN/GaN device, which is attributed to higher two-dimensional electron gas (2DEG) density and a thinner barrier layer in Al0.83In0.17N/GaN owning to lattice matching. On the other hand, the open gate geometry was found to affect the pH sensitivity obviously. Properly increasing the width and shortening the length of the open gate area could enhance the sensitivity. However, when the open gate width is too larger or too small, the pH sensitivity would be suppressed conversely. Designing an optimal ratio of the width to the length is important for achieving high sensitivity. This work suggests that the AlInN/GaN-based 2DEG carrier modulated devices would be good candidates for high-performance pH sensors and other related applications.

show abstract

Section: Discussionmentioning

confidence: 99%

High Sensitive pH Sensor Based on AlInN/GaN Heterostructure Transistor

Yan

Son

Dai

et al. 2018

Sensors

View full text Add to dashboard Cite

show abstract

“…Compared to the well-understood carrier property in p-n junction, the carrier dynamics at the p-GaN/electrolyte heterojunction is more complex with involvement of strong interaction between nanowire surface and electrolyte ions/molecules, while apparently offering more variables in tuning charge-transfer behaviors and subsequently affecting the ultimate optoelectronic characteristics. [17][18][19] Previous works reveal that the pristine p-GaN/electrolyte interface may suffer large charge-transfer impedance raised by charge trapping from surface states, [20] leading to poor efficiency of the reduction reaction. With the help from co-catalyst loading on surface, the decorated adlayer may act as passivation layer to eliminate the charge-trapping effect, [20][21][22] enabling fast charge transfer from GaN to the adlayer.…”

Section: Working Principles Of the Bipolar-junction Photoelectrodementioning

confidence: 99%

Light‐Induced Bipolar Photoresponse with Amplified Photocurrents in an Electrolyte‐Assisted Bipolar p–n Junction

Fang

Wang

et al. 2023

Advanced Materials

View full text Add to dashboard Cite

The p–n junction with bipolar characteristics sets the fundamental unit to build electronics while its unique rectification behavior constrains the degree of carrier tunability for expanded functionalities. Herein, a bipolar‐junction photoelectrode employed with a gallium nitride (GaN) p–n homojunction nanowire array that operates in electrolyte is reported, demonstrating bipolar photoresponse controlled by different wavelengths of light. Significantly, with rational decoration of a ruthenium oxides (RuOx) layer on nanowires guided by theoretical modeling, the resulting RuOx/p–n GaN photoelectrode exhibits unambiguously boosted bipolar photoresponse by an enhancement of 775% and 3000% for positive and negative photocurrents, respectively, compared to the pristine nanowires. The loading of the RuOx layer on nanowire surface optimizes surface band bending, which facilitates charge transfer across the GaN/electrolyte interface, meanwhile promoting the efficiency of redox reaction for both hydrogen evolution reaction and oxygen evolution reaction which corresponds to the negative and positive photocurrents, respectively. Finally, a dual‐channel optical communication system incorporated with such photoelectrode is constructed with using only one photoelectrode to decode dual‐band signals with encrypted property. The proposed bipolar device architecture presents a viable route to manipulate the carrier dynamics for the development of a plethora of multifunctional optoelectronic devices for future sensing, communication, and imaging systems.

show abstract

“…A site-binding model that was initially proposed for the oxide/aqueous sensing mechanism is currently in use to explain the sensing principle for AlGaN/GaN HEMT-based pH sensors [ 38 , 39 ] because a natural oxide layer (such as Al x O y and Ga x O y ) is formed on the surface of the AlGaN and GaN layer when the device is exposed in air [ 33 ]. Figure 2 presents the operating principle of the proposed HEMT-based pH sensor.…”

Section: Basic Structure and Operation Principlementioning

confidence: 99%

Low-Power pH Sensor Based on Narrow Channel Open-Gated Al0.25Ga0.75N/GaN HEMT and Package Integrated Polydimethylsiloxane Microchannels

Yang

et al. 2020

Materials

View full text Add to dashboard Cite

pH sensors with low-power and strong anti-interference are extremely important for industrial online real-time detection. Herein, a narrow channel pH sensor based on Al0.25Ga0.75N/GaN high electron mobility transistor (HEMT) with package integrated Polydimethylsiloxane (PDMS) microchannels is proposed. The fabricated device has shown potential advantages in improving stability and reducing power consumption in response to pH changes of the solution. The performance of the pH sensor was demonstrated where the preliminary results showed an ultra-low power (<5.0 μW) at VDS = 1.0 V. Meanwhile, the sensitivity was 0.06 μA/V·pH in the range of pH = 2 to pH = 10, and the resolution of the sensor was 0.1 pH. The improvement in performance of the proposed sensor can be related to the narrow channel and microchannel, which can be attributed to better surface GaxOy in a microchannel with larger H+ and HO− concentration on the sensing surface during the detection process. The low-power sensor with excellent stability can be widely used in various unattended or harsh environments, and it is more conducive to integration and intelligence, which lays the foundation for online monitoring in vivo.

show abstract

Charging mechanism of AlGaN/GaN open-gate pH sensor and electrolyte interface

Cited by 5 publications

References 15 publications

High Sensitive pH Sensor Based on AlInN/GaN Heterostructure Transistor

High Sensitive pH Sensor Based on AlInN/GaN Heterostructure Transistor

Light‐Induced Bipolar Photoresponse with Amplified Photocurrents in an Electrolyte‐Assisted Bipolar p–n Junction

Low-Power pH Sensor Based on Narrow Channel Open-Gated Al0.25Ga0.75N/GaN HEMT and Package Integrated Polydimethylsiloxane Microchannels

Contact Info

Product

Resources

About