Semiconductor Device Modeling and Simulation (INDSE8C) — DU B.Sc. (Hons) Instrumentation Previous Year Question Papers

Q.1 (a) Under equilibrium conditions andT> OK, whatistheprobability of an electron (2) state being occupied if it is located at Fermi level? a) (c) (d) What are degenerate semiconductors? Draw energy-band diagram of degenerated p-type semiconductor (2) Draw Energy -Momentum diagram for an indirect band gap semiconductor. Mention any two industry standard softwares used for semiconductor device (2) (e) Differentiate between FinFET and HEMT. a The hole concentration in a piece of Si maintained at 300K under equilibrium conditions is 106/cm3. What is the electron concentration? (2) Q.2 (a) What is the significance of Modeling in semiconductor industry? What are the three levels of modeling w.r.t semiconductor industry? (5) a) Define density of states. Express it mathematically (c) State the three fundamental equations that form the basis of most classical semiconductor device models in Technology Computer Aided Design (TCAD) (b) A silicon ingot is doped with 1017 Arsenic atoms/cm3. Find the carrier (4) concenti-ations and the Fermi level at room temperatui.e (300 K). (c) A si wafer is uniformly doped n-type with ND= 1016/cm3. At T=OK, what are the equilibriuni electron and hole concentrations? (3) Q.4 (a) For a non-degenerate n type semiconductor, plot-energy band diagram, density (5) of staes, Fermi distribution function and carrirer concentration (b) D.efine mobility w.r.t semiconductors. How is mobility related to effective mass of the caITier? (c) Assume that, in an n-type semiconductor at T = 300K, the electron concentration varies linearly from 1 x 1018 to 7 x 1017 cm-3 over a distance of o.1 cm. Calculate the diffusion current density if the electron diffusion coefflcient is Dn = 22.5 (3) a Q.5 (a) Differentiate between Lattice scattering and ionized impurity scattering. (5) (b) (c) What is Generation of charge carriers? Explain any two types of generation (4) processes using suitable energy-band diagrams. State the general form of the continuity equation for holes in a semiconductor. Explain what each tern physically represents? (3) Q.6 (a) (b) Draw a flowchart illustrating the sequential steps involved in simulating a p- (5) MOSFET using an industryistandard Technology Computer Aided D.esign (TCAD) tool to analyse its electrical characteristics. Derive the expression for built in potential for a p-n junction under equilibrium (4) (c) A si step junction maintained at room temperature under equilibrium conditions has a p-side doping of NA= 2X 1015 cm-3 and n-side doping of ND= 1015 cm-3. Calculate (i) Electric field at the metallurgical junction (x=0) (ii) Depletion width onn side-xn (3) Q.7 (a) (b) (c) Compare the distribution of the electric field and the space charge density in a step-graded p-n junction under two conditions: (i) at thermal equilibrium (zero bias), and (ii) after the application of a forward bias.