Silicon And Porous Silicon – Based Extended Gate Field Effect Transistor For pH And Cations Sensor
Loading...
Date
2018-06
Authors
Kabaa, Emad Adnan Said
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Following the advances in biochemical sensors based on porous silicon (PSi) in
the late 20th century, several studies have been carried out to take advantage of the
intrinsic properties of PSi for development of biochemical sensors. The commercial ntype
silicon (Si) has been used in two forms, namely, flat surface and porous layer
based on extended gate field effect transistor (EGFET), as sensors for the pH and
cations (Na+, K+, Mg2+, and Ca2+). This study aim is to improve the low silicon
sensitivity as a cations sensor by increasing the surface area in a cheap and simple way.
This study characterizes Si and PSi by using two orientations (111 and 100) in
improving and achieve high sensitivity of silicon for pH, Na+, K+, Mg2+, and Ca2+
sensors based EGFET. Also, this study investigates the selectivity of Si and PSi for
H+, Na+, K+, Mg2+, and Ca2+; and hysteresis phenomena as an indicator of sensor
stability. It has been used the electrochemical method to form the porous structure for
the two Si orientations (100 and 111) considering the fixed values for the parameters
affecting the chemical etching process. The used parameters were selected
experimentally (current density, illumination, concentration of solution, etching time,
and temperature). The morphological characteristics of porous silicon (PSi) layers
were investigated by field-emission scanning electron microscopy. The pore diameters
for PSi (111) ranged from 250 nm to 750 nm with PSi layer thickness of 18.94 μm. By
contrast, the pore diameters for PSi (100) ranged from 1 μm to 6 μm with thickness of
55.37 μm. Ion-sensing system based on EGFET was developed and the sensitivity for
pH, Na+, K+, Mg2+, and Ca2+ was calculated using the reference voltage and drain
current sensitivity.
Description
Keywords
Biochemical sensors based on porous silicon , in the late 20th century