7/24/2019 PUT NEC 302 2015-16

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AKGEC/IAP/FM/03

Ajay Kumar Garg Engineering College, Ghaziabad

Dear!men! o" ECE

Pre#$ni%er&i!y 'e&!

Cour&e( )*'e+h eme&!er( III

e&&ion( -0.#. e+!ion( EC#.,-,3 1 EI

ubje+!( Fundamen!al& o" Ele+!roni+ De%i+e& ub* Code( 2EC#30-

Ma Mar4&( .00 'ime( 3 hour&

Note( A!!em! all e+!ion&*

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5*. A!!em! all ar!&* All ar!& +arry e6ual mar4&* 7ri!e an&8er o" ea+h ar! in &hor!*

9-.0 : -0;

9a; 7ha! i& &hor! diode>

since the contact potential is the maximum forward bias that can appear across a unction. %he

appearance of a forward oltage across an illuminated unction is nown as the photovoltaic

effect.

9"; 7hy minori!y +arrier& genera!ion i& limi!ed 8i!hin one di""u&ion 9ou!&ide dele!ion

region; "or in+rea&ing re%er&e &a!ura!ion +urren!*

*hen V is negatie (reerse bias), the exponential term approaches +ero and the current is -I0,

which is in the n to p (negatie) direction. %his negatie generation current is also called the

reverse saturation current. As&

9g; Men!ion !he ali+a!ion o" nega!i%e +ondu+!an+e de%i+e&*egatie resistance oscillators are mainly used at high frequencies in the microwae range or

aboe, since feedbac oscillatorsfunction poorly at these frequencies. icrowae diodes are

used in low- to medium-power oscillators for applications such as radar speed guns, and localoscillators for satellite receiers. %hey are a widely used source of microwae energy, and

irtually the only solid-state source of millimeter wae and terahert+energy

9h; Di""eren!ia!e "lore&+en+e and ho&hore&+en+e*

If the recombination occurs for direct rather than ia a defect leel band, band gaps light is gien

off in the process. #irect recombination is a fast process and is called as florescence. $nlieflorescence, a hosphorescent material does not immediately re-emit the radiation it absorbs.

%his slow process is called phosphorescence and the material is called phosphorus.

9i; 7ha! i& inje+!ion ele+!rolumine&+en+e