Mohabbat,

welcome,

Any internal space charge region at the interfaces of two different materials called also the junction between two materials is modeled always by the socalled space charge layer capacitance or the junction capacitance Cj.

It can be expressed by

Cj= epsilon A/ dj

where dj is the thickness of the space charge region.

If there is an oxide layer between two conducting or semiconducting materials.

It has also an oxide capacitance.

If you have Metal insulator semiconductor you will get the socalled MIS capacitance. It has complicated behavior with applied voltage.

If you give a drawing of the physical structure i can give a specific advise to you.

Best wishes

Mohabbat,

welcome,

Any internal space charge region at the interfaces of two different materials called also the junction between two materials is modeled always by the socalled space charge layer capacitance or the junction capacitance Cj.

It can be expressed by

Cj= epsilon A/ dj

where dj is the thickness of the space charge region.

If there is an oxide layer between two conducting or semiconducting materials.

It has also an oxide capacitance.

If you have Metal insulator semiconductor you will get the socalled MIS capacitance. It has complicated behavior with applied voltage.

If you give a drawing of the physical structure i can give a specific advise to you.

Best wishes

Bhattacharya, R. N., H. Shen, P. Parayanthal, Fred H. Pollak, T. Coutts, and H. Aharoni. "Electroreflectance and photoreflectance study of the space-charge region in semiconductors:(In-Sn-O)/InP as a model system." Physical Review B 37, no. 8 (1988): 4044.

The depletion region sometimes could extends along the entire p or n material, due to this, the generated carriers can generate a considerable photocurrent. For this reason, you must take into account in you calculations.

Best regards