EE-130/230A, Spring 2020 HW 4 Due in the beginning of class on 03/31/2020 Problem 1[10 pts] Consider a Metal Semiconductor Schottky diode is fabricated with PtSi contact and a p-doped Si (NA=1018cm-3). (a) Draw the energy band diagram (b) Draw the profile of charge density in this diode. Can you comment on the nature of the charge density that you are drawing for the PtSi side of the junction? (c) Draw the potential profile and calculate the built in potential. (d) Draw the energy band profile under forward bias (e) Qualitatively explain how current flows in this device in forward and reverse bias. Problem 2[10 pts] A MS contact is formed between a metal and a semiconductor such that fm=c. Under what conditions will the contact be ohmic and under what conditions will the contact be rectifying? Problem 3[10 pts] Consider a tungsten barrier on silicon with a measured barrier height of efBn=0.67 eV. The effective Richardson constant is K=114 A/˚K2-cm2 . T=300K. Find out the reverse saturation current density. Now consider a pn junction diode at T=300K with the following parameters: Na= 1018 /cm3 Nd=1016 /cm3 tp=tn=10-7 sec. Find out the reverse saturation current for this pn junction diode. Comment on the reverse saturation current of these two diodes. Problem 4[10 pts] For a Schottky barrier diode where Si is doped to Nd=7x1018 /cm3, and barrier height is 0.67 eV, find out the depletion region width. Problem 5 [10 pts] Construct a plot of the equilibrium depletion width versus the Nd doping concentration in silicon MS diodes maintained at T=300K. Vary Nd over the range 1014/cm3<Nd<1017/cm3 and include curves corresponding to barrier heights of 0.5, 0.6 and 0.7 eV.