Process-Property Relationships For a-Si_1-xC_x:H Deposition: Excursions in Parameter Space Guided by Real Time Spectroellipsometry

Abstract

Real time spectroellipsometry (RTSE) has been applied to study the growth of a-Si1-xCx:H alloys (x∼0.1; Eg=1.90–2.00 eV) for applications as i- and p-type layers in wide band gap solar cells. Two important material parameters, the optical gap and the relative bond-packing density (or void volume fraction), can be estimated from RTSE data collected during the growth of a sequence of layers onto the same substrate using different plasma-enhanced CVD conditions. In this way, large regions of parameter space have been scanned expeditiously, and an improved understanding of the effects of H2-dilution, substrate temperature (Ts), plasma power, gas pressure, and gas flow on the film properties has been obtained.

Deposition phase diagrams for Si1−xGex:H from real time spectroscopic ellipsometry

“…Similar observations of an optimum electronic quality at maximum R had been presented earlier for Si 1Àx C x :H alloys [7], although the now well-known dependence of the amorphous-to-(mixed-phase microcrystalline) transition on accumulated thickness (that motivates multistep processing, in fact) [4,8] had yet to be recognized. Thus, the maximum dilution concept is also expected to hold for the Si 1Àx Ge x :H alloys.…”

Real time spectroscopic ellipsometry of thin film Si/sub 1-x/Ge/sub x/:H: phase diagrams for optimization in photovoltaics applications

“…Similar observations of an optimum at maximal R had been presented previously for a-Si 1,Cx:H alloys [4]. and thus these observations are also expected to hold for the Si l ,Ge,:H alloys.…”

Enhanced Growth Rate and Silane Utilization in Amorphous Silicon and Nanocrystalline-Silicon Solar Cell Deposition via Gas Phase Additives

“…These types of structural transitions and growth evolutions have been observed for Si:H prepared under a variety of deposition conditions 1 and its alloys with germanium 19 (Si 1-x Ge x :H) and carbon 20 (Si 1-x C x :H). The comparison of the behavior of these transitions as a function of single deposition parameters has been used to produce so-called deposition phase diagrams or growth evolution diagrams, which have guided the development of optimization principles in Si:H-based PV.…”