Figure 36.

(a) Drain–source current variations measured as a function of gate potential at a fixed drain–source potential of −0.5 V for ss-DNA (marker DNA), after hybridization with complementary target ss-DNA to form ds-DNA and after removal of DNA by washing. A gate potential shift of approximately 80 mV is detected on this DNA-FET with approximately 4×10¹² cm⁻² molecules bonded to the gate. (b) Gate potential shifts as detected on diamond transistor structures with 10¹², 4×10¹² and 10¹³ cm⁻² ss-DNA marker molecules bonded to the gate area. The threshold potential is increasing towards less dense grafted diamond gates areas.