Akhil,

I would like to pay your attention that the quantity which is given as a property for the semiconductors is the mobility u rather than the diffusion constant  D.They are related by the relation D= Vt u where Vt is the thermal voltage kT/q. The motility itself is a function of the temperature T and doping for a specific material. Also, the diffusion length is not given directly in the data sheets of the material. The disillusion length L is given by the sq. root of D Tau. where Tau is the life time. The life time is a technological parameter and varied in a wide range for a given material depending on its technology of formation.

So, the mobility ranges from few cm^2/V s to hundreds of the same unit,

The life time varies in a much wider range from nanoseconds to 100s of microseconds,

The diffusion length ranges from fraction of a  micrometer to 100s of micrometers.

The last comment is that Aluminum oxide is not a semiconductor it is an insulator.

wish you success

Akhil,

maybe would be interesting to know what are you trying to do, are you conducting some solar cell simulations with a specific software? These two magnitudes are usually calculated from carrier mobilities and lifetimes, as Abdelhalim says, which in turn are dependent on several parameters. If you need to have an idea of values you can check the Ioffe website. Note that Al2O3 is used as a passivation layer, and it is an insulator.

In addition to the statements already added you need to be aware of the thicknesses and interface quality of each of your layers.  You could have a really long calculated diffusion length for each individual material region but if there is an interface with high surface recombination velocity relatively close then the effective diffusion length of the material is diminished.  So your total cell simulation would be ideal if you just accounted for the best diffusion lengths and didn't account for interfaces.

Dear Prof. Zekry,

Thank you for the information.

I am working on Simulation of I-V Characteristics of Quantum Dot Solar Cells (single junction GaAs+InAs QD and GaAs+GaSb QD). To determine the Effective Surface Recombination Rate, the specific values of Diffusion Constant and Diffusion Length are required.

I can continue my work with the information you provided.

Thank you.