Thickness Evolution Of The Microstructure Of Si : H Films In The Amorphous-To-Microcrystalline Phase Transition Region

Real time spectroscopic ellipsometry (RTSE) has been applied to develop deposition phase diagrams that describe the thickness evolution of the phase of hydrogenated silicon (Si:H) thin films. Such diagrams can be applied to establish optimization principles for the intrinsic (i-) layers incorporated into high performance solar cells based on amorphous Si:H (a-Si:H). The phase diagrams for the growth of Si:H on a-Si:H film substrates incorporate two transitions versus accumulated thickness, the first from the amorphous to the mixed-phase (amorphous + microcrystalline) growth regime [the a-->(a+muc) transition] and the second from the mixed-phase to single-phase microcrystalline growth regime [the (a+muc)-->muc transition]. Methods have been developed to extract the evolution of the volume fraction of microcrystalline Si:H (pc-Si:H) within the mixed-phase growth regime. Similar deposition phase diagrams have also been developed to optimize p-type Si:H layers for a-Si:H-based n-i-p and p-i-n cells.