(20) For certain applications, it is advantageous to fabricate the MOSFET in a thin film of silicon on an insulating substrate, referred to as silicon-on-insulator (SOI). a) (10) Define the role of SOI. b) (10) Specify the advantages of SOI in fabricating MOSFET at least three. Gox 3.9 x 8.85 x 10-14 F/cm - AVT = [20FP+ VSB 20Fp] The effect of a channel implant on the threshold voltage can be approximately represented as follows: VI,new = VT,old + eN,/Cox "old" refers to without the implant and "new" refers to with the implant. N, is the carrier concentration/cm of the implant. When the designers investigated the process, they found that the typical value of VSB for the n-MOSFET in the various gates was VSB = 1.0 V which increase the typical threshold voltage VT above the VT value. a) (20) What is the value of N, for an implant that will give a typical V7 (with VSB = 1.0 V) value of 0.5 V. b) (10) Based on calculation above, is the implant donors or acceptors and explain why.