Mind Map (Semi)

* Nucleus of any atom is +ve charge

1.2.1 Formation of a junction *Placing p-type silicon next to n-type silicon is the primary way many semiconductor devices are constructed

* Material with full valence electron and excellent conductor

*The Free electrons and holes are trying to move across the N and P junction.

* valence orbit outermost orbit 1.1.1 Conductor and Insulator 1.1.1.1 Atom Structure :Conductor

1.0 INTRODUCTION TO

*The +ve and –ve ions within the junction caused there is a voltage different between the 2 types materials

1.1.2 Semiconductor

*Two types of  semiconductivematerials are silicon and germanium. *Silicon and Germanium atoms have four valence electrons. 1.1.2.1.1 Silicon *Silicon has 4 valence electrons *can form covalent bonds with each other 1.1.2.1.2 Germanium *amount of heat energy needed to move one of the electron valence to a higher orbit level

1.2.1.3 Threshold voltage and its values for Silicon and Germanium

SEMICONDUCTOR

*copper wire is use to conduct electricity

1.1.2.1 Atom Structure : Semiconductor

*Free electrons and holes are trying to move across the N and P junction. *Electrons in N type material are strongly attracted to fill holes in P-type materials

*Electrons in N type material are strongly attracted to fill holes in P-type materials.

* valence electron have 29 electrons and photons * the valence electron are weakly attracted to the nucleus

. . . mobility

1.2.6 Breakdown during reverse biased *These free electrons will collide with other bonding *Reverse current flow occurred and the value increased simultaneously. *This limit is known as insulation breakdown limit. *It can cause the P-N  joint burn

*The voltage different is same like a small battery where the voltage different is known as barrier voltage. *The value of barrier voltage is small. (Where for Ge semiconductor ≈ 0.3V and Si semiconductor ≈ 0.7V)

1.2.1.2 Depletion region and its properties *In the N type material, the electrons become depleted near the junction. *The combination will cause atoms near the joined  junction become neutral *The neutral regions with no current carriers is called depletion region

1.2.2 Forward bias voltage and reverse bias voltage supplied across a P-N  Junction. *Definition of biased voltage: *2 types of biased voltage: –Forward-bias –Reverse bias

1.2.3 Effects on P-N junction when supplied with forward and reverse biased 1.1.3 The characteristics of N-type and Ptypesemiconductor *Dopingis a process of adding other materials called impuritiesto the silicon crystal *One such impurity material is arsenic which known as a donor impurity *Donorimpurities have 5 valence electrons *N-typesilicon has been doped with a donor impurity to make it semiconduct *Acceptorimpurities have 3 valence electrons *P-typesilicon has been doped with an acceptor impurity to make it semiconduct.

1.2.4 Area of depletion region *Electrons in N type material will move forward to the  junction that cause the depletion region become smaller and the resistant across it will decrease *When forward bias increased over the value of barrier voltage (0.3V for Ge semiconductor and 0.7V for Si semiconductor)

1.2.5 Current Flow (include leakage current) *It is a minority current in materials *This current is known as leakage current or reverse current. *Electrons in P-type material is pushed by the reverse-bias voltage to the joint region and passed through it.