Miniaturized diamond field-effect transistors for application in biosensors in electrolyte solution

Abstract

The authors fabricated diamond solution-gate field-effect transistors (SGFETs) with miniaturization of the channel length to 5μm by photolithography. The channel surface was directly functionalized with amine by ultraviolet irradiation in an ammonia gas for 4h and aminated diamond SGFETs were sensitive to pH by 40mV∕pH. Urease was immobilized on the amine-modified channel surface, which was sensitive to urea by 27μA/decade from 10−5M to 10−2M. The authors fabricated submicron-sized (500nm) diamond SGFETs using electron-beam lithography. The transconductance (gm) was 56mS∕mm, which was 930-fold greater than that of the 500μm channel length.