University:
University of South Wales
Course:
NG3S921 | Advanced Semiconductors
Academic year:

2023
Views:

142

Pages:

4
Author:

Rebecca L.

A hola indicates a missing elechon in this, под no more than the hodes is no: of elechong. In N-type Semiconductors the no: of boles is less than the no of free electon An p-type semiconductor majsouty charge carriers are holes and minosity Charge coarcors are dorbons In type semiconductor majority Charge corners are dochong and minonty charge carries Are holes P-N Junchon diode Prl Junction odiode/Semiconductor diode / crystal diade → If one side of a Semiconductor crystal is doped coich acceptor impurity atom and the other side of the same crystal is doped with donay impurity *Represented as: (+) (-) Depletion Layer & potential Barrier of a Junción diode -The n-side of p.nl junchion has more è and p. has more boles. When junction is formed, electrons and holes migrate in all direchon. Ca sideaudonor 100810 tole Prypentype. Each time an è crosses the junction a is created in the n-type and negative depletion Layer +ve ion in p-type. When sufferent cons are created (net pr the charge on n-side and -ve on P-side) These charges produces an dechic field which opposes further flow of elections bem D-region to p-region. This field acts as a barrier and is called internal potenhal barrier (1PB) (Vo) * Vo of Silicon = 0-7V * Vo of Ge 0-3 Deplehon layer: A thin layer on each side of the junction has no free electons or holes. This Layer is depleted off free charges and is Called depletion layer/ space charge region The distance blw the hoo ends of the depletion layer is called width of the barrier Cabut 5 Depending on the nahae of semiconductor and its doping, worth width of depletion layer may change Electric field devoloped across junción, E = VIPB , Vo/d d thickness of depletion layer Biasing of P-N Junchon Biasing: connecting cell across p.nl Junction It can be done in 2 ways, a) Forcoard biaşing b) Reverse biaging/Backward biasing a. Forward biasing • Connecting the positive terminal of the battery to the p-type and negative terminal to the n-type of the Pri Junction is asaid to be forward blasing depleton layer - deder the Forward bias, the elechon from the n-region and files from the P-region flow through the function in opposite direction The potential barrier hight is reduced. The appled p.d across the IPB. If the appled pid is greater than IPB current flows through the junction. When the junction & forward biased, Potenhal barrier is reduced and it disappeas at a certain forward voltage From O.1V to 0-3V. 1) widds of depletion layer is decreased The juncion coffers a very low resistance. (the Forward reses fance) w) Elechon fuom n-region and filor flow from p-region through the junchon is opposde direction and give rise to forward current b. Reverse biasing • Connecting the negative terminal to the p-type and the Positnie terreinal to the n-type of the p-r yunchon is called reverse biasing • When the junction is reverse biased, ) The width of the depletion layer is increased (i (ii) The potential baxuey of the applied voltage increased by the magnitude (m) The jerochon offers a high resistance called the reverse resistance (v) No current flows in the corcut due to majority Carriers