Ultrasound-induced nitride formation on the surface of single-crystalline GaAs in cryogenic fluid

We have developed and successfully used a new method for structuring semiconductor surfaces that is based on the phenomenon of cavitation excited by focused ultrasound in a liquid medium. In this work, the cavitation impact of ultrasound at a frequency of $\sim$ 1 MHz and a power density of $\sim$ 15 W/cm$^2$ on the surface of single-crystalline (001) GaAs in liquid nitrogen led to the formation of a submicron-sized relief of rippled and concentric structures with a height of up to 300 nm. Data of Raman spectroscopy and energy-dispersive X-ray spectroscopy showed the formation of GaAs$_{1-x}$N$_x$ surface compound with a nitrogen content of 5–7%.