**3.2.2 Schottky diode**

310 Solar Cells – Thin-Film Technologies

more stable behaviors are observed in the triode-deposited a-Si:H films in the degraded states. The trend is best seen in the film prepared at the *d*ms of 4 cm where the lowest Si-H2

Fig. 7. Change in the neutral spin density (*N*s) due to light soaking as a function of Si-H2

Fig. 8. Light-induced change in the fill-factor (*FF = FFini - FFdeg*) of the Schottky diode having the intrinsic layer produced at the each condition. Closed circle: triode-deposited film (triode), open circle: conventionally prepared film (diode). [Shimizu et al., 2005]

bond density is observed as shown in figure 3.

bond density in the film. [Shimizu et al., 2008]

Furthermore, the stabilities of the triode-deposited a-Si:H films were studied with fabricating the Schottky diodes where their fill-factor (*FF*) changes were evaluated as a measure of degradation. The intrinsic layer of the Schottky diode was fabricated either by a triode or a diode system under the various conditions. The fill-factors in the initial state (*FF*ini) are almost the same throughout the samples: 52 - 54 %. On the other hand, the fill-factors in the degraded state (*FF*deg) are different each other. In figure 8, the change in the fill-factor (*FF* = *FF*ini – *FF*deg) is plotted against Si-H2 bond density [Shimizu et al., 2005]. For comparison, those of the films prepared with the diode system under the various conditions are also shown [Nishimoto et el., 2002]. One can see that the triode-deposited a-Si:H films contain low Si-H2 bond densities, and correspondingly, the observed *FF*s are low. Note that, the scattered correlation is observed when *FF*s are plotted against the Si-H densities of the films [Shimizu et al., 2005].
