Formation of periodic structures on silicon surface by plasma flow in pulsed plasma accelerator

Surface modification of single-crystal Si (100) wafers under the exposure of a pulsed high-density helium plasma stream in a quasi-stationary accelerator yields, periodic micro and nanostructures at different operational conditions. At 5 kV operating voltage, sub-100 nm ripples and nanocones are observed on Si surface which is attributed to localized melting and rapid quench dynamics driven by plasma deceleration-induced heating. Increasing the operating voltage to 8 − 12 kV, periodic micrometer-scale wrinkles with 6–37 μm pitch are observed by SEM and AFM analysis of the Si surface. From AFM roughness metrics, the increment in observed roughness values (S a increased from 1.05 nm to 19.67 nm; S q from 1. 88 nm to 25.82 nm) and four-point probe measurements (resistance drop from ~ 4 × 106 Ω to ~ 1 × 105 Ω) underscore the enhancement in surface area and electrical conductivity resulting from plasma treatment. This study sheds new light on the morphological development of silicon surfaces and opens up new possibilities for silicon-based electronics.