For C-V curve below for 3 different materials, (Si, InAs, InSb). What material will be corresponding to curve A/B/C?
My understanding is that C is inversely proportional to the dielectric constant in the inversion region. As a result, Si has the smallest dielectric constant and therefore matches with C.
InAs = B InSb = C
Is my understanding correct? Thank you for your help!
Yes. You are correct, if they all have the same cros sectional area and same doping concentration in the semiconductor.
For a MOS capacitor, the capacitance value in inversion region is given by the the series combination of insulator capacitance (\$C_{ox}\$) and the semiconductor capacitance in inversion (\$C_{s}\$). Since all the three capacitors have same capacitance in the accumulation region, \$C_{ox}\$ values are same. \$C_s\$ depends on dielectric constant of the semiconductor (\$\epsilon_s\$) and doping in the material. So if the doping is can be assumed to be same, then MOS capacitor with least \$C_s\$ will have lowest capacitance.
