Question

Q2 MOSFET and I-V Curves (Total 30 pts) Q2.1 Consider the band diagrams (conduction band) of a N-MOSFET along the channel (x) direction as shown in fig. 1. In fig. 1, the solid curve shows the band diagram with the gate voltage VG = 0. All the variables have their usual meaning. Which of the dashed curves (case I or case II) in fig. 1 represents of the band diagram (conduction band) of the N-MOSFET with VG >0? 5 pts Circle your answer. (Case I / Case II ) Gate Oxide Type=p Doping=N Case V=0 Case 11 E., Source E. Semi E., Drain Figure 1: Band diagram of a N-MOSFET along the channel (2) direction.

Answer 1

And 2.1 ts asked in the question, the energy band diagram for Vayo will be dashed were with case - I Reason? When we opply positive voltage in the gate terminal of nuos (Valo) the p- region below the gate ( the channel) starts getting depleted from holes and turning to accumulation of minority eleefrens, region of electron ar (n-type) channel will be formed. Hence the differenu between construction band energy detween n-region and channel reegion will be decreased and case I will be the result. CA Ansa.2 A (mA) 2.4 1 19 T linear i / saturation 12 | fald autols! Va (v) Given Vs =0, so Vos avo-Vj = VD - Vesa Vu Vs = VG cut off when fp =0, At vu a lv this is happening

linear : When, Vos & Vas uve - » from the figure it can be seen that upto Vu= av, fo is small and not changing drasting drastically wort Va, hence this is linear region. Above vuozv. current is in saturation. van 2.3 On set of saturation : Nos = Vus-ve . Voo Vas Vt = 3-1 - 2 v Vo corresponding to this where is av. Amb 2.4 on sel- of sturation: Voc ve-Vt from the were given in fig. 3, ah set of Saturation, voz3v Va aur Ves VaVp - 4-3 - Iv

saturation - Vazar on set of saturation : (Voovna Vt in this point) t s av Nocu And 2.5 We know that, - Ans25 fig: 3 Jo = { unbox (%) (ven - V4) from » 1:42 = { uncea ("%) (4-2) Vua 1. » {un cox (2) all hence saturation curref at Uno su In a toma con (2) (No - vej alget (3-1 . luggy 0.6355mA 142 Ma con cm Iga 0.6355 mA x All the best