Semiconductor Physics Unit PDF

Here is the markdown conversion of the document: # Unit II # Semiconductor * **Semiconductor:** It is a material whose properties lie between a conductor and an insulator. * The most commonly used semiconductor materials are Silicon (Si) and Germanium(Ge). * It is the most popular beca...

Here is the markdown conversion of the document: # Unit II # Semiconductor * **Semiconductor:** It is a material whose properties lie between a conductor and an insulator. * The most commonly used semiconductor materials are Silicon (Si) and Germanium(Ge). * It is the most popular because it can be controlled according to requirements. **Conductor** * It is a material in which electrons can flow, but it cannot be controlled as per requirements. * Example: Gold, silver, copper, aluminium, etc. **Insulator** * It is a material in which electrons cannot flow. * Example: Wood, plastic, rubber. * Why is Silicon (Si) is the most preferable compared to Germanium? 1. Silicon is abundant in nature. 2. It is the cheapest. 3. Thermal stability is higher, and it is less temperature sensitive. 4. The power handling capacity of silicon is higher than germanium. * The efficiency of silicon is higher than germanium. ## Types of Semiconductors They are of two types: 1. Extrinsic Semiconductor (आन्तरिक अर्धचालक) 2. Extrinsic Semiconductor (बाह्य अर्धचालक) ### Intrinsic $\implies$ Extrinsic The impure semiconductor is called extrinsic. In other words, if extra impurities are added to it, it is called the extrinsic semiconductor. ### There are two types of Extrinsic Semiconductors 1. P-type Extrinsic 2. N-type Extrinsic ### P-type Extrinsic $\implies$ Intrinsic If trivalent impurities are added to a pure semiconductor, it is called a P-type semiconductor. * The trivalent impurities are Boron(B), Aluminum(AI), Gallium(Ga), Indium(In), and Thallium(TI) ## Structure of P-type $Si=2.8.4$ * When trivalent impurities like Boron (B) are added to a pure semiconductor than, a covalent bond between the Silicon is broken, and free electrons are generated because Boron, having three electrons in its outmost orbit, try’s to gain one electron from the silicon. * After getting the one electron, a negative ion appears on the Boron atom. Simultaneously, holes are created and some free electrons. **In other words, a P-type consists of three things:** 1. Holes( Majority carriers) 2. Electrons( Minority carriers) 3. Negative Zones ## N-Type Semiconductor If pentavalent impurities are added to a pure semiconductor, it is called an N-type Semiconductor. pure+pentavalent The pentavalent impurities are. Nitrogen(N), Phosphorus(P), Arsenic(As), Antimony(Sb), Bismuth(Bi) If pentavalent impurities like phosphorus are added in silicon, a pure semiconductor covalent bond breaks. Between, presented at the phosphorus atom emigrates one electron. In the crystal atom emits one electron, in the crystal therefore positive zone appears. On the Phosphorus atom Some notes are also present in minority carriers due to movement. In other words, we can say, an N-type consists of three things 1. Positive Ions 2. Hole- (Minority) 3. Electron- (Minority) ## PN TYPE OR PN JUNCTION OR DIODE When p-type and n-type semiconductors are combined with each other, then holes are present in the p-type, and electrons present n-type get diffused due to the force of attraction of this process. This is carried out in one drive stage, which then diffusion process stops. As a result, + Ion In N Type and – negative Ion In P-type near the Junction exist. This Reason is Called “Space Change Region or depletion Region of pn-junction” * At the middle and one terminal is taken out that is called anode. * Similarly at middle and of n-type. one terminal is also taken, that is called cathode. It seems a p-n device having two terminals, an anode, and a cathode. Therefore it is also called a Diode. ## Important **Symbol of Diode** * **Biasing** $\implies$ Connection of a battery or cell through a PN- junction, is called biasing * There are two types of Biasing 1. Forward Biasing 2. Reverse Biasing ### Forward Biasing When p-type of diode terminal is connected through the positive terminal of battery and n-type or cathode terminal is connected through the negative terminal of battery than diode is set to be forward- break down. Biasing. In other words, when the anode terminal is connected through the positive terminal of the battery and cathode terminal is connected through the negative terminal of the battery than diode, are said to be forward biasing. * That Is $V_A>V_k$ ### Biasing- डायोड में Battery लगाने की प्रक्रिया * When reverse bias voltage is applied through a PN junction diode, then electrons and holes get the energy from that source. * When voltage increases more than the width, the depletion region increases gradually, there is no electron or hole. cross the junction and therefore, no current flows through the Diode is said to be in an OFF state. But a practically small amount of electrons cross the barrier due to temperature and thermally generated carriers. * When the value of reverse bias voltage keeps on increasing, one stage comes when sudden change in current and diode get break down and this is called reverse breakdown voltage## Reverse Changctristic of Diode OR VI Chanactristic of Diode in Reverse Bias * * * ### Qus. Explain working of PN Junction diode. Explain VI Characteristics of diode. * $SI=0?$ * $Ge=0?$ Reverse * $V_R$ = Reverse breakdown voltage * $V_{FB}$ = Forward breakdown voltage * shockley's eauation. * `Intrinsic Impedenae)` a constant <!-- --> - **NOTE** If it is not mentioned in the question consider it is made up of silicon -Thermal Voltage $V_T=\dfrac{KT}{q}$ * at Room Temprature That is 25-TO 2je $V_T \approx 26 mV$or 25 my\\Since VT = KT q * Where $k \longrightarrow Boltz Max's Constant$$K=1.38\times 10^{23} j/k$ * $\Tau$ tempratune in kelvin 2ijc 30QK (275+27)$q= Change > 1.6×10^\circ c$ 4 AT Room Temprature V₁ = 1.38×10-23 ×800 1. 6×1019 **Question- Find the current trurough a Dinade** * **10 124 din le voltage (VD) = 0.5 V ANE WE** * 25.85 m Assuming of germinium * $I = 0.012A,$ VF= V₁= 25.85×103 V ## 2. find the Reverse Saturation current * **through the germinium diode of** the value of Diole voltage is 15 OV current Through the to be diode25mA Considet Therind voltage is *28.85 mv - * * * IO=? n=1 U= A.J I = 0.25 MA = 0.25x503 20 = 25.85mV= 25,35x1 * * * We know that * I = * "Intrinsic Impedenze") an constant For siliconi 2 ge >\ I" from ego" and ego ## **Types of Diode** 1. **Simple P-n.Dinde** (VVD) 2. **Zener Din de** 3. **light Emiting Diode** 4. **P=I=N** * * * # Dr Dorglie Dave-8- Acoording to De Buroglie, particle. Savrounded by wave Whose wavekngt is dependen on mass of the parken (on) # "Dr, = mc * If particle having velocity (u) then, 2mv= p * "If the genetic energy of the gassis qiven Kinetic energy of the gassis ## DIAGRAM It is always, operated in four-ward bias Condition. Its most use in catelite Commusication. ## [HALL - EFFECTI *"According to Hall." Ef any Semiconductor It any A magnetic field (9) * having Gument (1) then electric field in Blectrie - force Magnetic force * "Electric Aree is Gual to Magnetic Force ### "Comdurtivity I" for Non-dispersiersive medium 4 * Since ### "Reverse Changctristic of Diode" * "That is <!-- --> ### Forward Biasing's When p-type of Dmode Terminal is Connectes through positive terminal of batting and N-type Therefore An N = Chorge - "Number of charge charge Density' Give 24