Open AccessAtomic-scale characterization of hydrogenated amorphous-silicon films and devices. Annual subcontract report, 14 February 1994--14 April 1995
Author(s) -
A. C. Gallagher,
David M. Tanenbaum,
Arnaldo Laracuente,
Branislav Jelenković
Publication year - 1995
Language(s) - English
Resource type - Reports
DOI - 10.2172/95549
Subject(s) - materials science , void (composites) , amorphous silicon , silicon , scanning tunneling microscope , amorphous solid , nanocrystalline silicon , agglomerate , photovoltaics , silane , optoelectronics , particulates , semiconductor , nanotechnology , crystalline silicon , photovoltaic system , composite material , crystallography , chemistry , organic chemistry , ecology , biology
Properties of the hydrogenated amorphous silicon (a-Si:H) films used in photovoltaic (PV) panels are reported. The atomic-scale topology of the surface of intrinsic a-Si:H films, measured by scanning tunneling microscopy (STM) as a function of film thickness, are reported and diagnosed. For 1-500-nm-thick films deposited under normal device-quality conditions from silane discharges, most portions of these surfaces are uniformly hilly without indications of void regions. However, the STM images indicate that 2-6-nm silicon particulates are continuously deposited into the growing film from the discharge and fill approximately 0.01% of the film volume. Although the STM data are not sensitive to the local electronic properties near these particulates, it is very likely that the void regions grow around them and have a deleterious effect on a-Si:H photovoltaics. Preliminary observations of particulates in the discharge, based on light scattering, confirm that particulates are present in the discharge and that many collect and agglomerate immediately downstream of the electrodes. Progress toward STM measurements of the electronic properties of cross-sectioned a-Si:H PV cells is also reported