Use MathCAD to solve the following problems:

1. An n⁺-polysilicon-gate n-channel Si-MOSFET with substrate doping N_A=5x10¹⁵ cm^-3. The insulator is SiO₂, and its thickness is 400 A. The interface charge Q_ox =5x10¹⁰ qC/cm², the gate length is 1 um, and the gate width is 40 um

1. Find W_m, V_FB, and V_T.
2. For V_G= 5V, obtain the current at V_D= 1V.
3. For V_G=5V, (i) find the saturation current, (ii) the current at pinch-off, and (iii) the current at V_D=5V.
4. Are the currents in (C) equal to each other? Should they should be equal, or this is just a coincident? Explain.
5. Is this device enhancement or depletion mode device?