Question
mosfet
5. Consider an Aluminum-SiOz-Ip-Sil Mos device at T 300 K The work function of Al is 4.1 eV the electron affinity for Sioz and Si are 095 ev and 405 eV respectively The intrinsic carrier concentration of a p-Si is n, 1.5x cm 3 and the bandgap energy is 1-1 eV The relative permittivity for Si and Sioz are 118 and 39, respectively Fig. 1(a shows energy levels in three separated materials that form an MOS system. Fig. 1b) is the energy band diagram at thermal am for the MOS system of Fig. 1(b) under flat-band condition where an external va tage Va equal to V is applied between the metal and the silicon (a Find ay and in Fig, (c) Find Vr and in Fig. 1lc0. (d) Find the electrostatic potential dG) and draw it as a function of x with (x 30 in Fig. 10bl. (e Find the electric field intensity E() and draw it as a function of x in Fig. 10bx (f Find the depletion width W, the acceptor concentration Ne for x>W, and the axide thickness f in Fig 10b (g) Find the threshold gate voltage VG of a MOS system in Fig. 1 bl ie the gate voltage ch) Calculate the maximum depletion width in semiconductor at the onset of the strong etion width capacitance C, at VG
Explanation / Answer
a) qxm = 0.5 rV
b) qr = 0.211 eV
c) Vrb = 5.2 V
d) electrostatic potential = 3.3 V
e) electric field intensity = 15642.32 N/C
f) depletion width = 5.78 micrometer
g) threshold gate voltage = 4.56 V
h) maximum depletion width = 10.72 micrometer
i) Ct = 8.34 nF , Cs = 6.32 nF
