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Reg No. Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
THIRD SEMESTER B.TECH DEGREE EXAMINATION, JANUARY 2017 Course
Code: EC203
Course Name: SOLID STATE DEVICES (AE, EC)
Max. Marks: 100 Duration: 3 Hours
PARTA

Question No. | is compulsory. Answer question No. 2 or 3

1. (a) Derive the expression nopo= 1४ from fundamentals. (5)
(b) A germanium sample is doped with 1016 boron atoms per പണ്‌. Find the electron
concentration. Intrinsic carrier concentration of germanium is 2.5 x 10'*/em7at300K.
(5)

(०) An n- type silicon sample with Na = 1015 /em’ is steadily illuminated such that

2० = 1020 EHP/cm3-sec. 18, at = lusec for this excitation. Draw the energy band

diagram with the quasi Fermi levels at 300K. Intrinsic carrier concentration of silicon
is
1.5 x 1010 /ണ 3 (5)
2. (a) Explain the temperature dependence of carrier concentration of an extrinsic
semiconductor with the help of graph. (5)
(b) What is Hall Effect? Derive the expression for finding the carrier concentration of a
semiconductor from Hall voltage. (10)
OR
3. (a) What is Einstein Relation? Derive the expression. (5) (b)

Derive Continuity equation. Find the expression for the distribution of carriers in a
semi-infinite semiconductor bar if steady injection of carriers occurs at one end. (10)
PART B
Question No. 4 is compulsory. Answer question No. 5 or 6

4. (a) Draw the charge density and electric field distribution within the transition region of a

PN Junction with Na
(b) An abrupt silicon PN junction has Na = 107 /em 3 and N= 107 /em 3. Draw the

energy band diagram of the junction at equilibrium at 300K and find its contact potential

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