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&p [e{"-x )/Lr - e(x""l)IL"} eULP _ e-l,Lp in .NET Display Code128 in .NET &p [e{"-x )/Lr - e(x""l)IL"} eULP _ e-l,Lp EAN 13 for .NET

&p [e{"-x )/Lr - e(x""l)IL"} eULP _ e-l,Lp use none none writer toaccess none in none.net ean 13 generating Junctions (b) Show that the current in the diode is I= Microsoft Office Word Website (^-i)( ). 5.36 Given the narrow base none none diode result (Prob. 5.

35), (a) calculate the current due to recombination in the n region, and (b) show that the current due to recombination at the ohmic contact is /(ohmic contact) = (~ " c s c h y - \ ^ v " k T - 1). 5.37 Assume that a p+-n ju nction is built with a graded n region in which the doping is described by Nd(x) = G^.The depletion region (W = xnQ) extends from essentially the junction at x = 0 to a point W within the n region.

The singularity at x = 0 for negative m can be neglected. (a) Integrate Gauss"s law across the depletion region to obtain the maximum value of the electric field 0 = -^GV0m+1)/e(m + 1). (b) Find the expression for %(x), and use the result to obtain V0 - V = mt2) /e(m + 2).

9GW< (c) Find the charge Q due to ionized donors in the depletion region; write Q explicitly in terms of (V0 - V). (d) Using the results of (c), take the derivative dQ/d(V0 - V) to show that the capacitance is C- = A qGe m+\) [m + 2)(V0 " V). l/(m+2). 5.38 We deposit a metal wi th a work function of 4.6 e V on Si (electron affinity of 4 eV) and acceptor doping level of 1018 cm-3.

Draw the equilibrium band diagram and mark off the Fermi level, the band edges, and the vacuum level. Is this a Schottky or ohmic contact, and why By how much should the metal work function be altered to change the type of contact Explain with reference to the band diagram. 5.

39 Design an ohmic contact for n-type GaAs using InAs, with an intervening graded InGaAs region (see Fig. 5-44). 5.

40 A Schottky barrier is formed between a metal having a work function of 4.3 eV and p-type Si (electron affinity = 4 eV).The acceptor doping in the Si is 1017 cm-3.

(a) Draw the equilibrium band diagram, showing a numerical value for qVQ. (b) Draw the band diagram with 0.3 V forward bias.

Repeat for 2 V reverse bias.. Very useful applets for un none none derstanding diode operation are available at http:// jas.eng.buffalo.

edu/. DCAniNG LIST Campbell, S. A. The Scienc none none e and Engineering of Microelectronic Fabrication, 2d ed.

NY: Oxford, 2001.. 5 . Chang, L. L., and L.

Esaki none none . "Semiconductor Quantum Heterostructures." Physics Today 45 (October 1992): 36-43.

Muller, R. S., and T.

I. Kamins. Device Electronics for Integrated Circuits.

New York: Wiley, 1986. Neamen, D. A.

Semiconductor Physics and Devices: Basic Principles. Homewood, IL: Irwin, 1992. Pierret, R.

F. Semiconductor Device Fundamentals. Reading, MA: Addison-Wesley, 1996.

Plummer, J. D., M.

D. Deal, and P. B.

Griffin. Silicon VLSI Technology. Upper Saddle River, NJ: Prentice Hall, 2000.

Shockley, W. "The Theory of P-N Junctions in Semiconductors and P-N Junction Transistors." Bell Syst.

Tech. J. 28 (1949), 435.

Wolf, S., and R. N.

Tauber. Silicon Processing for the VLSI Era., 2d ed.

Sunset Beach, CA: Lattice Press, 2000. Wolfe, C. M.

, G. E. Stillman, and N.

Holonyak, Jr. Physical Properties of Semiconductors. Englewood Cliffs, NJ: Prentice Hall, 1989.

. SELF QUIZ Question 1 Consider a forw none none ard-biased ideal (abrupt junction, no recombination or generation in the depletion region) long p-n junction diode under forward bias. On the following graph, sketch and label the total current I,olal, the total electron current In>[olai and the total hole current Iplolai as a function of position throughout the entire device. The value of each has been given at the n-side edge of the depletion region for reference.

(Hint: the excess carrier concentrations are essentially pinned to zero at the contacts.).
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