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Unformatted text preview: Question 1. Consider an Ohmic contact whose geometry is defined in Figure 3.5.1 of the online text. The metalsemiconductor contact resistivity is 106 cm 2 and the sheet resistance of the thin semiconductor layer is 10 . a) What is the contact resistance times the width, R c W , if the contact length, d , is much longer than the penetration depth? b) What is the minimum contact length, d , if the contact resistance times the width, R c W, must be less than twice the value obtained in a)? What is the ratio of that contact length, d , to the penetration length? c) Construct a normalized line graph with R c / R c ( d = ) vs. d / for such contact and add the solution of b) on the figure. a) The contact resistance times the width and the penetration length are obtained from: c s c R W R = 3.16 mOhmcm and s c R = 3.16 micron b) For R c ( d ) = 2 R c ( d = ), tanh( d / ) = 0.5, from which d / = 0.549, so that d = 1.74 micron c) The normalized resistance is given by d d R R c c coth ) ( as shown in the figure below together with the solution of part b). together with the solution of part b)....
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 '08
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