Hello Prasanna,

In TCAD Sentaurus, you can either allow the simulator to select the default material parameter file or you can define the user specified parameters. Just have a look at the default materials library available in TCAD Sentaurus: $STROOT/tcad/$STRELEASE/lib/sdevice/MaterialDB

Moreover for mole fraction dependent material parameters, if you know the physical mole fraction dependent equations to compute all material parameters, you can manually calculate and include it in the TCAD simulation. Otherwise, define the mole fraction of the material in the physics section, TCAD Sentaurus automatically compute the material parameters based on the specified mole fraction. Please have a look at the chapter "Defining Devices" in Sdevice Manual for more information. 

In the default TCAD parameter file of InGaAs, they have included the complex refractive index. Pls. find the attachment. Hope it helps!

Thank you Nandhakumar  very much for your response 

In that file they gave n,k values for mole fraction 0.4 ,0.7,0.75,0.8 and 0.85 ranges but they didn't gave for 0.47 or in that range, and also if i use this .par file its shows no absorption at 1.55um wavelength but we well known that at 1.55um In0.53Ga0.47As will have good max efficiency and absorption.