Abstract

Ultrafast electrical signals have been generated from metal-semiconductor-metal photoconductive switches utilizing low-temperature-grown substrates, or a technique of electron-beam lithography to realize narrow photoconductive gaps. The fastest response of 0.87 ps has been achieved by the photoconductive switch of a 300-nm gap made on a low-temperature-grown GaAs substrate.¹ On the other hand, the fabrication of semiconductor nanostructure based on a scanning tunneling microscope (STM) or an atomic force microscope (AFM) has been developed rapidly. We made a photoconductive switch⁴ oxidizing Ti thin film by an AFM, which is the method recently proposed² and developed.³

© 1996 Optical Society of America