Question

Problem 8 Intrinsic conductivity in Si 11/6/2019 ESG 333 Effective masses, mobilities and energy gaps can be measured directly For example: for Si: effective masses: m 0.33 mecon (these are averages) m 0.56 mekctros 0.13 m2/(V. s) at RT: e Ec 1.11 eV Hh0.05 m/(V. s) (see pages 138-142 of notes) For intrinsic Si (no impurities): a) Calculate the relaxation times t, Th and the chemical potential u (at T- 300 K) b) Calculate the average number of conduction e s per unit volume (n) at T (remember the intrinsic density of holes, p, is equal to n) 300° K c) Calculate the ratio (use 4 valence e/atom) number of valence e /unit vohme R = n (in Si, the number of atoms/cm2 is 5.00 x 102) d) Calculate the conductivity o and resistivity p for Si. Calculate resistance for the sample below 10 mm 1 mm 2 mm e) How does this o compare with that of Cu (59.6 x 10 . m)?

solve for c and d

Answer 1

Calulate the ratio (use 4 velence é lunit volume) R= no. of Valence é (unit volume 4 x 5x10² 6.023x1023 6.023 = 3.32x10!!!

d) for an lotija ) camioneta (some p>") - Tain + 4) Pensions. C- I Pagepro (for Pure re si for Intrinsic Silicon at 3ook Mr = 1450 ; Mp= 505&n=p=n. = 9.65000 1 . (- qp cep tha) • q= 16 min c { charge of election } 1.6x1079 x 9.65*10** (1450 + 505) Boziloise 3.31x102 cm) (1) 331288-181 32-cm.

Conducting 331288.181 15 = 3.01852x10 s cm (or) skom ..Rx 9.65009 (1450+505) - [R = 18865.75*109 5.3410th