CONDUCTOR INSULATOR SEMICONDUCTOR The elements which allow the flow of electric current through it by the application of voltage. Good conductor. The elements which do not allow any flow of electric charge. The elements whose conductivity lies between insulators and conductors. Bad conductor. Wood, Rubber, Glass, Ebonite, Mica, Sulphur, Dry air. Energy Band. Copper, Mercury, Silver, Al, Water, Acids, Human Body, Metallic Salt, Charcoal. Conduction band and valence band overlap each other. At 0K works, it works as an insulator while by applying thermal agitation or by adding impurity becomes good conductor. Germanium, Silicon, Cotton, Wool, Marble, Sand, Paper, Ivory, Moist air. Conduction band and valence band are separated by 6eV. Conduction band and valence band separated by 1eV. Temperature Coefficient. Positive temperature Coefficient of resistance. Negative Temperature Coefficient of resistance. They do not contain any charge carriers. Negative Temperature Coefficient of resistance. Intrinsic charge carriers are holes and electrons. Current flow due to electrons. Current does not flow. Current flow due to holes and electrons. Very High. Negligible. Low. Valence band and conduction band is completely filled. Valence Band is completely filled and conduction band is completely empty. Valence band is partially empty and conduction band is partially filled. BASIS FOR COMPARISON Definition. Electric Conductivity. Examples. Electrons. Charge carriers. Current Flow. Number of Charge Carriers. Valence band and conduction Band. Effect of temperature on conductivity. On Increasing Temperature. Conductivity decreases. Conductivity Increases. Conductivity Increases. The number of current carriers decreases. The number of current carriers increases. The number of current carriers increases. Resistance Increases. Resistance remain unchanged. Resistance Decreases. Takes place easily. Does not take place. Very Slow. Behaves like super conductor. Behaves like an Insulator. Behaves like an Insulator. Ionic bond. Ionic Bond and Covalent Bond. Covalent Bond. Effect of doping. Current Flow under the influence of electric field. Behaviour at Absolute 0K temperature. Bonding Types. Comparison Chart of Conductor, Insulator and Semiconductor: Comparison Chart Of Zener Breakdown And Avalanche Breakdown: PARAMETERS ZENER BREAKDOWN Basic Definition It occurs when the electric field is created due to high reverese voltage. Less than 5 V High Doping density Exhibit Negative temperature coefficient Very Sharp Reverse Voltage Range Doping density Temperature Coefficient Nature of V-I Characteristics Mechanism Due to collision between electrons AVALANCHE BREAKDOWN It occurs when high velocity electrons collide with bounded electrons. More than 5 V Low doping density Exhibit Positive temperature coefficient Not as sharp as Zener Breakdown Due to High electric field Comparison chart of Diode and Zener Diode: PARAMETERS Definition DIODE Diode is a semiconductor device which conducts only in forward biased. Operation in Reverse Biased It gets damaged in reverse biased. ZENER DIODE Zener diode is semiconductor device which can conduct in forward as well as reversed biased. It can operate without getting damaged. Circuit Symbol Doping Intensity In normal diodes doping intensity is low. Application Diode is used in rectifiers, clippers, clampers etc. DIODE PARAMETERS In Zener diode doping intensity is high to achieve sharp breakdown. Zener diode is mostly used in voltage regulator. ZENER DIODE Comparison Chart of Diode and Transistor: Parameter Definition Diode A diode is a two terminal device which allows current to pass in one direction only. Formation It is formed by joining a Ptype semiconductor with Ntype semiconductor. Transistor Transistor is a three terminal device which allows current to flow from high resistance region to low resistance region It is formed by sandwiching a layer of P-type or N-type material between two N-type or P-type material on either end. Circuit Symbol Depletion Layer Number of Junctions Terminals Only one depletion region is formed. Only one junction between P-type and N-type semiconductor. 2 terminals are there in a diode i.e. anode and cathode. Two depletion region are formed. Two Junctions are formed one in between emiter and base and other between base and collector. 3 terminals are there in transistor i.e. emitter, base and collector. Considered as Applications It can be considered as a switch. Rectifier, voltage double, clipper etc. It can be considered as a switch or an amplifier. Amplifier, Oscillator etc. Comparison Chart of NPN Transistor and PNP Transistor: Parameter Definition Majority Charge Carriers Circuit Symbol Direction of Majority Charge Carriers Direction of Current Direction of arrow in circuit NPN TRANSISTOR Transistor which consists of one layer of P-type material sandwiched between two layers of N-type semiconductor. Electrons PNP TRANSISTOR Transistor which consists of one layer of N-type material sandwiched between two layers of P-type semiconductor. Holes Electrons flow from emitter to collector. Current flows from collector to emitter. Outwards from base Holes flow from emitter to collector. Current flows emitter to collector. Inwards to base terminal. symbol Acts as Mobility of Charge carriers terminal. It acts as current source as it sources current from base terminal of transistor. Electrons possess high mobiltiy thus conduction is more Commonly Used NPN transistor is used in most of the applications. Frequency Response Faster response than PNP transistors. It acts like current sink as it completely sink the current towards base terminal. Holes are less mobile in copmparison to electron thus, PNP transistor provides less condcution. PNP transistor is less used in comparison to NPN transistor. Slower frequency response.