S. C. Jackson

Novel photochemical vapor deposition reactor for amorphous silicon solar cell deposition

A novel photochemical vapor deposition (photo‐CVD) reactor having a flexible ultraviolet‐transparent Teflon curtain and a secondary gas flow to eliminate deposition on the window has been used to deposit amorphous silicon films and p‐i‐n solar cells. The background levels of atmospheric contaminants (H2O, CO2, N2) depend strongly on the vacuum procedures but not on the presence of a Teflon curtain in the reactor. Intrinsic films with a midgap density of states of 3×1015 eV−1 cm−3 and all‐photo‐CVD pin solar cells with efficiencies of 8.5% have been deposited.

Molecular beam distributions from high rate sources

A mathematical model that describes the evaporated flux from high rate sources like those used in the deposition of semiconductor films were developed from mass balances with suitable constitutive equations describing the molecular beam distribution. The model was experimentally verified in laboratory scale equipment. Good agreement between the measured distributions and model results were obtained using a single fitting parameter. The fitting parameter is material specific and was correlated to the Knudsen number at a fixed location in the nozzle. A generalized procedure to evaluate this parameter and estimate the incident flux from a molecular beam source is outlined.