Mobility, lifetime and diffusion length in polycrystalline materials

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A model to study the effect of grain boundary states density of the polycrystalline metal‐insulator‐semiconductor (MIS) solar cell paramenters is presented. It assumes a uniform insulatorsemiconductor (I–S) surface state density (Nss) and the increase in the density at the I–S surface due to grain boundary appearing at the interface. The results in a change of interfacial charge and hence barrier height (φb), diode quality factor (n) and the current in the device. Under illuminated condition the I–S charge changes due to the capture of photogenerated carriers. The overall effect of the charge density at the I–S interface is reflected in the degradation of the cell parameters with decreasing grain size (D).

Section: Introductionmentioning

confidence: 99%

Effect of grain boundary states density in polycrystalline MIS solar cells

Goyal

Kumar

Sen³

1989

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On the resistivity of polycrystalline silicon

Tyagi¹,

Sen²

1983

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Theoretical investigations of the influence of grain size (D) and doping density (NA), on the carrier concentration (p*) and effective resistivity (ϱ*) of polycrystalline silicon are made, considering the finite thickness (2t) of the grain boundary region and the dynamics of capture and release of carriers at the grain boundary trap‐states. It is found that for low values of impurity concentration the average carrier concentration (p*) and the effective resistivity (ϱ*) are controlled by trapping of free carriers at the grain boundary trap‐states where, as for higher doping densities, the values of p* and ϱ* tend to those of a single crystal as a result of saturation of the trapping states.

Grain Size and Temperature Dependence of the Electrical Behaviour of Polysilicon

Tyagi¹,

Sen²

1984

Self Cite

The effect of grain size (D) and temperature (T) on the electrical behaviour of polysilicon is investigated theoretically by considering a simplified carrier trapping model and an empirical expression for grain boundary trapping states density. The model presented applies well for all grain sizes over the entire range of doping concentration and temperature. The computed variations of electrical properties, such as resistivity and mobility, with D and T are seen to be in agreement with the experimental findings. It is observed that the effect of temperature is more pronounced for smaller grain sizes whereas for larger values of D the properties tend to those of a single crystal.