Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications

184 Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications

© 2011 by Taylor & Francis Group, LLC

species will not be desorbed and therefore poisons the site for future adsorption of oxygen. The

specic on-state resistance of the rectier RON is given by

R

ON

= (4V

2

B

/ εµE

3

M

) + ρ

s

W

S

+ R

C

,

where ε is the ZnO permittivity, µ the carrier mobility, ρ

s

and W

S

the substrate resistivity and thick-

ness, and RC the contact resistance. Over a relatively limited range of CO partial pressures in the N

2

ambient, the on-state resistance decreased according to R

ON

= (R

O

+ A(P

CO

)

0.5

)

−1

, where A is a con-

stant and R

O

is the resistance ...