Ion Beam Treatment of Functional Layers in Thin-Film Silicon Solar ...

List of Figures
2.1 Schematic diagrams of the discharge zone in close drift ion sources/thrusters. 10
2.2 Magnetic and electric field in the discharge zone of anode layer ion source. 11
2.3 Configuration of linear anode layer ion source used in this work. . . . . . 13
2.4 Energy distribution of oxygen ions at 5 sccm oxygen gas flow into a linear
anode layer ion source. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.5 Wurtzite structure of ZnO crystal. . . . . . . . . . . . . . . . . . . . . . . 21
2.6 Optical transmission, reflection and absorption of a typical ZnO:Al film. . 25
2.7 Burstein-Moss broadening of the optical band gap of degenerate semiconductors.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.8 The schematic drawing of magnetron sputtering. . . . . . . . . . . . . . . 28
2.9 Schematic drawing of randomly textured, out-of-plane textured, and biaxial
textured thin films. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.10 Modified Thornton-model for RF-sputtered ZnO:Al films . . . . . . . . . 31
2.11 SEM micrographs of a series of ZnO:Al films deposited under different
conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.12 Comparison of the local surface morphology for surface with similar
roughness σ, but different values of α. . . . . . . . . . . . . . . . . . . . . 34
2.13 Representative height-height correlation function obtained from a selfaffine
surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.14 Representative power spectrum density function obtained from a selfaffine
surface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.15 Diagram of growth effects including diffusion, reemission and shadowing
that may effect the surface morphology during thin-film growth. [1] . . . 37
2.16 Monte Carlo simulated β value as a function of sticking coefficient s 0 for
sputter deposition. It is assumed that the sticking coefficient of the second
strike at the surface for the re-emitted atom is 1 [2]. . . . . . . . . . . . . 38
2.17 Absorption coefficient of a-Si:H, µc-Si:H and crystalline Si (c-Si) as a
function of photon energy. . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2.18 Schematic diagram of a single junction Si thin-film solar cell. . . . . . . . 42
2.19 Typical curve for current density as a function of voltage in dark and
illuminated. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.1 Sketch of the vertical in-line deposition system. . . . . . . . . . . . . . . 46
3.2 Photo and Geometry of the linear anode layer ion source. . . . . . . . . . 48
3.3 Schematic diagram of the ion beam treatments with non-tilted ion source
and tilted ion source. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
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