Abstract

Decreasing the finger spacing and width of metal-semiconductor-metal (MSM) photodetectors can greatly improve their speed and sensitivity. Smaller finger spacing leads to shorter transit time and higher sensitivity; smaller linger width to spacing ratio leads to smaller capacitance and therefore shorter external response time. We have fabricated MSM photodetectors of nanometer finger spacing and width as small as 25 nm on bulk GaAs and Si substrates using ultrahigh resolution electron beam lithography and a lift-off process. Typically, we employ one of two resist schemes in patterning extremely fine metal fingers.

© 1992 Optical Society of America