Some Aspects of Reactive Complex Plasmas

Abstract

Reactive plasmas are nowadays widely used for technological applications. The spontaneous formation and growth of dust is a phenomenon frequently observed in such plasmas. The formation of dust particles has been observed in a great variety of different discharge types and in different kind of gases or gas mixtures. Due to the large variety of different phenomena that can be observed in reactive complex plasmas this article will address some selected (general) problems and examples that are specific for the physics and chemistry of such systems. These examples concern the formation and growth of dust particles in reactive plasmas, the mechanisms responsible for that growth processes, the spatial distribution of the dust particles within the discharge, the response of the plasma to the formation and growth of dust particles and some technological aspects.

Surprising temperature dependence of the dust particle growth rate in low pressure Ar/C2H2 plasmas

“…1, R p,LLS is constant in phase (IV). This is in perfect agreement with constant particle growth rates in comparable Ar/C 2 H 2 RF plasmas determined ex-situ by means of SEM by Berndt et al 4 Consequently, this is a verification that, indeed, n p is constant. In Fig.…”

“…Once these nanoparticles reach a critical density, they rapidly coagulate (III) to ultimately form permanently negatively charged particles, typically 20-50 nm in size. After coagulation, the particle size increases linearly 4 by deposition of plasma species on their surface (stage IV) while their density n p remains constant; 7 i.e., the negatively charged particles are confined within the positive plasma potential and no new particles are created since reactive species are rather deposited on the particle's surface than creating new particles. When the particles become too large, the confining electric force is not able to overcome the nonconfining ones anymore, the particles are lost from the discharge and n p starts to decrease.…”

Dust particles in low-pressure plasmas: Formation and induced phenomena

“…Dusty plasmas are due to the simultaneous presence in the same place of dust particles and plasmas, but a noteworthy aspect is that dust particles can be formed in the plasma itself. In this last case, the fundamental requirement is the presence of molecular precursors [11]. These precursors result from the presence of reactive gases (silane SiH 4 [5,[12][13][14][15][16], methane CH 4 [17][18][19], acetylene C 2 H 2 [17,20,21]) or from material erosion (physical or chemical) at the molecular level [22][23][24][25][26].…”

Nanoparticle growth in ethanol based plasmas

“…For example, Fig. 4a shows a nanoparticle surface close to the typical cauliflower structure observed in hydrocarbon plasmas [14]. On the contrary, Fig.…”