Extended Gate Field Effect Transistor-Based N-Type Gallium Nitride as a pH Sensor

Abstract A SPICE model for extended-gate field-effect transistor (EGFET) based pH sensor was developed using standard discrete components. Capacitors and resistors were used to represent the sensing and reference electrodes in the EGFET sensor system and the values of the discrete component were varied to see the output of the transistor. These variations were done to emulate the EGFET sensor output in different pH values. It was found that the experimental transfer and output characteristics of the EGFET were very similar to those from the SPICE simulation. Other than that, the changes of value components in the equivalent circuit did not affect the transfer and output characteristics graph, but the capacitor value produced significant output variation in the simulation. This can be related to the modification on the equivalent circuit was done with additional voltage, VSB (source to bulk) to produce the different VT values at different pH.

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Gallium Nitride Normally-Off Vertical Field-Effect Transistor Featuring an Additional Back Current Blocking Layer Structure

Electronics ◽

10.3390/electronics8020241 ◽

2019 ◽

Vol 8 (2) ◽

pp. 241 ◽

Cited By ~ 1

Author(s):

Huolin Huang ◽

Feiyu Li ◽

Zhonghao Sun ◽

Nan Sun ◽

Feng Zhang ◽

...

Keyword(s):

Gallium Nitride ◽

Field Effect ◽

Field Effect Transistor ◽

Blocking Layer ◽

Vertical Field ◽

Current Blocking Layer ◽

Effect Transistor ◽

Vertical Field Effect ◽

Vertical Field Effect Transistor ◽

Current Blocking

A gallium nitride (GaN) semiconductor vertical field-effect transistor (VFET) has several attractive advantages such as high power density capability and small device size. Currently, some of the main issues hindering its development include the realization of normally off operation and the improvement of high breakdown voltage (BV) characteristics. In this work, a trenched-gate scheme is employed to realize the normally off VFET. Meanwhile, an additional back current blocking layer (BCBL) is proposed and inserted into the GaN normally off VFET to improve the device performance. The electrical characteristics of the proposed device (called BCBL-VFET) are investigated systematically and the structural parameters are optimized through theoretical calculations and TCAD simulations. We demonstrate that the BCBL-VFET exhibits a normally off operation with a large positive threshold voltage of 3.5 V and an obviously increased BV of 1800 V owing to the uniform electric field distribution achieved around the gate region. However, the device only shows a small degradation of on-resistance (RON). The proposed scheme provides a useful reference for engineers in device fabrication work and will be promising for the applications of power electronics.

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Graphene Channel Liquid Container Field Effect Transistor as pH Sensor

Journal of Nanomaterials ◽

10.1155/2014/547139 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 29

Author(s):

Xin Li ◽

Junjie Shi ◽

Junchao Pang ◽

Weihua Liu ◽

Hongzhong Liu ◽

...

Keyword(s):

Field Effect ◽

Field Effect Transistor ◽

Ph Value ◽

Ph Sensor ◽

Drain Current ◽

Fast Response ◽

Monolayer Graphene ◽

Ph Sensing ◽

Order Of Magnitude ◽

Effect Transistor

Graphene channel liquid container field effect transistor pH sensor with interdigital microtrench for liquid ion testing is presented. Growth morphology and pH sensing property of continuous few-layer graphene (FLG) and quasi-continuous monolayer graphene (MG) channels are compared. The experiment results show that the source-to-drain current of the graphene channel FET has a significant and fast response after adsorption of the measured molecule and ion at the room temperature; at the same time, the FLG response time is less than 4 s. The resolution of MG (0.01) on pH value is one order of magnitude higher than that of FLG (0.1). The reason is that with fewer defects, the MG is more likely to adsorb measured molecule and ion, and the molecules and ions can make the transport property change. The output sensitivities of MG are from 34.5% to 57.4% when the pH value is between 7 and 8, while sensitivity of FLG is 4.75% when thepH=7. The sensor fabrication combines traditional silicon technique and flexible electronic technology and provides an easy way to develop graphene-based electrolyte gas sensor or even biological sensors.

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