A Dielectrically Modulated GaN/AlN/AlGaN MOSHEMT with a Nanogap Embedded Cavity for Biosensing Applications

Sensitivity Analysis of Al0.3Ga0.7N/GaN Dielectric Modulated MOSHEMT Biosensor

“…Impact of cavity dimensions on sensitivity.-The sensing capability of the device changes due to variation in the cavity dimensions like the height or length of the cavity. 17,29 By varying the height of the cavity, h CUG from 5 nm to 20 nm and keeping all the other parameters constant, it is observed that the sensitivity increases for different device parameters as the height of CUG decreases as seen in Fig. 3a.…”

“…Impact of dielectric constant of gate dielectric on sensitivity.-The device optimization is carried out by simulating the device for different gate insulators as presented in Table I for sensitivity towards neutral biomolecule κ ( = ) 8 .For our analysis, we have considered the high-κ dielectric HfO 2 κ ( = ) 25 which has been reported to give high sensitivity to pH, 26 followed by a rare-Earth oxide Gadolinium Oxide (Gd 2 O 3 κ )( = ) 16 which offers lower defects and lower leakage currents, 27 and Al 2 O 3 κ ( = ) 9 , which is used owing to its low defect, and high surface binding capacity 17 and compared with the conventional SiO 2 κ ( = ) 3.9 for a 20 nm cavity thickness with a length of 20 μm and gate length of 1 μm.…”

“…The sharp increase in the conduction band energy is due to the presence of the high-κ dielectric. 17 It is followed by a dip caused due to interface traps present at the hetero interface between the GaN cap layer and the AlGaN barrier layer. The barrier layer offers a slight rise in energy which falls as we move towards the AlGaN/GaN heterojunction where the 2DEG well is formed.…”

“…The device sensitivity is measured using absolute values. For neutral biomolecules Uricase (κ = 1.54), Urease (κ = 1.64), Streptavidin (κ = 2.1), Protein (κ = 2.5), Biotin (κ = 2.63), Cholesterol Oxidase (ChOx) (κ = 3.28), Glucose Oxidase (GOx) (κ = 3.46), 3-Aminopropyltriethoxysilane (APTES) (κ = 3.57), 17 Keratin (κ = 8) 23 have been considered. While for charged biomolecules analysis κ = 14 is considered in this paper pertaining to charged amino acids (κ = 11-25).…”

“…[11][12][13] To overcome scaling issues associated with Silicon Dioxide (SiO 2 ) as the gate dielectric, high-permittivity κ ( ) materials like Aluminium Oxide (Al 2 O 3 ) κ ( = ) 9 14 and Zinc Oxide (ZnO) κ ( = − ) 6 10 15,16 are reported in MOSHEMT-based sensors. While Al 2 O 3 is used owing to its low defect, and high surface binding capacity, 17 ZnO is selected due to its higher sensitivity, lower lattice mismatch, and bulk growth capability. 15 The choice of AlGaN/GaN as the sensing element material stems from its chemically stable nature and its capability to form ionic bonds which makes biomolecule attachment to its surface possible.…”