Figure 2 indicates energy band diagram with respect to various biomolecules of Biosensor of this proposed device structure for biomolecules having various dielectric constants shown in table.2. Electrons need the energy to jump from a lower energy level to a higher energy level. The dotted lines in the graph indicate the valence band and solid lines indicate the conduction band. The bandgap before tunneling is approximately 1eV. During tunneling, different energy levels in valance and conduction band can be observed for different biomolecules.
Table 2
Biomolecules with their Dielectric Values
Sl. No

Biomolecules

Dielectric Constant

1

DNA

8.7

2

Cellulose

6.1

3

Biotin

2.63

4

Streptavidin

2.1

5

APTES

3.57

Fig. 3 indicates variation of Potential for various dielectric values. Potential is minimum at the Source region and starts increasing across the channel and further increases in the Drain region. The potential starts from 0.64V and saturates at 1.51V. For different values of dielectric constant, the potential of the device changes. From the graph, we can observe that the steep and high potential is obtained for a greater value of the dielectric constant. Fig.4 indicates variation of Electric Field across channel of this device. In the graph, we can observe two peaks since we have two gates for our device structure. At each point, the electric field is measured, and the sharp points denote the junction. For DNA having the dielectric constant K=8.7, the electric field is 2.28x106 and 1.0x105. For Cellulose having dielectric constant K=6.1, the electric field is 2.16x106 and 1.0x105. For APTES having the dielectric constant K=3.57, the electric field is 1.97x106 and 1.0x105. For Biotin having the dielectric constant K=2.63, the electric field is 1.87x106 and 1.0x105. For Streptavidin having the dielectric constant K=2.1, the electric field is 1.8x106 and 1.0x105. For different values of dielectric constant, the electric field across the device changes. The electric field is directly proportional to the dielectric value and from the graph, we can observe that as we increase the value of dielectric constant the electric field across the device increases.
Figure 5 indicates plot of IV Characteristics for different values of dielectric constants by plotting the drain current (ID) in Amperes on the Yaxis, Gate voltage (VG) in Volts on the X axis. This voltage is varied in the steps of 0.05V. The channel length is kept constant at 50nm. From the figure, we observe that drain current increases as gate voltage increases from 0.1V to 1V. For Streptavidin having the dielectric constant, K = 2.1 the value of Id starts increasing from 0.9V. For biotin having the dielectric constant K = 2.63 the value of Id starts increasing from 0.75V. For APTES having the dielectric constant of K = 3.57 the value of Id starts increasing from 0.55V and saturates at drain current 4x108A and 1V. For Cellulose having a dielectric constant of K = 6.1 the value of Id starts increasing from 0.3V and saturates at drain current 4x10− 8A and 1v. For DNA having the dielectric constant of K = 8.7 the value of Id starts increasing from 0.15V and saturates at drain current 4x10− 8A and 1V.
Figure 6 indicates the plot of IV Characteristics for different values of dielectric constants by plotting the drain current (Id) in Amperes on the Yaxis, gate voltage (Vg) in Volts on the Xaxis. The voltage is varied in the steps of 0.05V. The channel length is kept constant at 50nm. The Yaxis is in the logarithmic scale. For Dielectric constant K = 2.1 Id is in the range of 10− 12A and saturates at the range of 10− 7A, similar characteristics are observed for all the materials with different dielectric values. All of these drain current values saturate at the range of 10− 7 A as shown in the figure.
Figure 7 indicates the plot of IV Characteristics for different values of cavity lengths by plotting the drain current (Id) in Amperes on the Yaxis, gate voltage (Vg) in Volts on the X axis. The cavity length is increased in the steps of 5nm. We have taken APTES Biomolecule of dielectric constant K = 3.5, which is a medium range of dielectric value. From the graph, we can observe that the value of Id starts increasing from 0.55V and saturates at drain current 4x1008A and 1V.
Fig. 8 shows the influence of ION current on this proposed device structure for distinct values of various dielectric constants. Inferring the above figure, we discover the raise in dielectric constant considerably raises the ON current. This is because an increase in k causes the electric current at the tunnel junction to increase, resulting in a reduction in tunnel width.