physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6-8-9itcu1voaye

<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Higher Concentration</B></Primary></p>
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<p>Depletion layer is thin, ~ $\mu m$</p>
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<p>Electric field is high in Reverse bias condition.</p>
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<p>Valence electrons going from valence band to conduction band.</p>
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<p>This is known as <span style="color:green">zener breakdown</span>.</p>
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<p>The p-n junctions which use this zener breakdown for the application, they are known as <span style="color:green">zener diodes.</span></p>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-037-0564.0.jpg"></p>
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Avalanche Breakdown$\to$<span style="color:blue">Higher Concentration</span>$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$Voltage Regulator$\to$Problem$\to$Photodiode$\to$Light Emitting Diode: LED$\to$Solar Cell
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Avalanche Breakdown$\to$Higher Concentration$\to$<span style="color:blue">I-V Curve Showing Avalanche and Zener Breakdown</span>$\to$Voltage Regulator$\to$Problem$\to$Photodiode$\to$Light Emitting Diode: LED$\to$Solar Cell
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<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Voltage Regulator</B></Primary></p>
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<p>Power supply is giving DC.</p>
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<p>Shunt resistance: $R_S$</p>
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<p>Put a zener diode in reverse bias condition.</p>
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<p>The zener diode: 5V for the breakdown</p>
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<p>2 watts as the power rating.</p>
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<p>$V_A = 10$ volts</p>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-051-1106.4.jpg"></p>
<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-01.jpg"></p>
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<footer style='font-size:18px'>
Avalanche Breakdown$\to$Higher Concentration$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$<span style="color:blue">Voltage Regulator</span>$\to$Problem$\to$Photodiode$\to$Light Emitting Diode: LED$\to$Solar Cell
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<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Problem</B></Primary></p>
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<p><strong>Current Through</strong> $1k \Omega$</p>
<p>$V = 5 \text{Volts}$</p>
<p>$ R = 1 k\Omega$</p>
<p>$ I_L = 5 mA$</p>
<p>$\underline{\text{Current in} {~R_s}}$</p>
<p>$I_s =\frac{5\text{volts}}{12.5\Omega} = 400mA$.</p>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-069-1489.2.jpg"></p>
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<hr>
<footer style='font-size:18px'>
Avalanche Breakdown$\to$Higher Concentration$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$Voltage Regulator$\to$<span style="color:blue">Problem</span>$\to$Photodiode$\to$Light Emitting Diode: LED$\to$Solar Cell
</footer>

<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Problem</B></Primary></p>
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<p>As you have upper limit on the current in zener, you also have a lower limit on the current in zener.</p>
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<p>In reverse bias breakdown condition you need a certain current.</p>
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<p>$\text{Current} {~I_L} = \frac{5V}{1k\Omega} = 5mA $.</p>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-069-1489.2.jpg"></p>
<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-073-1717.2.jpg"></p>
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<footer style='font-size:18px'>
Avalanche Breakdown$\to$Higher Concentration$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$Voltage Regulator$\to$<span style="color:blue">Problem</span>$\to$Photodiode$\to$Light Emitting Diode: LED$\to$Solar Cell
</footer>

<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Problem</B></Primary></p>
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<p><strong>Current</strong></p>
<p>${~I_L} = \frac{5V}{1k\Omega} = 5mA $</p>
<p>Voltage across, $R_s= 8-5 = 3 \text{Volts}$</p>
<p>$I_s=\frac{V}{R_s}=\frac{3V}{12.5\Omega} = 0.24A = 240 mA$</p>
<p>$I_D= 235 mA$</p>
<p><span style="color:blue">Source voltage should be greater than the Zener Breakdown.</span></p>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-073-1717.2.jpg"></p>
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<hr>
<footer style='font-size:18px'>
Avalanche Breakdown$\to$Higher Concentration$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$Voltage Regulator$\to$<span style="color:blue">Problem</span>$\to$Photodiode$\to$Light Emitting Diode: LED$\to$Solar Cell
</footer>

<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Problem</B></Primary></p>
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<p>$E=\frac{hc}{\lambda}$</p>
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<p>hc = 1240 eV.nm</p>
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<p>$\lambda = 400 ~nm$</p>
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<p>$E=\frac{1240~eV.nm}{400 ~nm} = 3.1 eV $</p>
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<p>$\lambda = 620 ~nm $</p>
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<p>$E = \frac{1240 eV.nm}{620 nm} = 2 {~eV} $</p>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-084-2037.6.jpg"></p>
<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-091-2214.0.jpg"></p>
<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-092-2262.0.jpg"></p>
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<footer style='font-size:18px'>
Avalanche Breakdown$\to$Higher Concentration$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$Voltage Regulator$\to$<span style="color:blue">Problem</span>$\to$Photodiode$\to$Light Emitting Diode: LED$\to$Solar Cell
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<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Light Emitting Diode: LED</B></Primary></p>
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<main>
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<p><strong>Recombination of electron - hole pair</strong></p>
<p>$ E_g $ should be in visible range</p>
<p>$ E_g \sim $</p>
<p>$1.8 \mathrm{eV}-3.2 \mathrm{eV} $</p>
<p>{Ga As},{Ga As P},{Ga Ni},{Ga I},{Sic}</p>
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<li><span style="color:blue">2014 Nobel Prize for Blue light emitting Diode.</span></li>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-112-2794.8.jpg"></p>
<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-125-2946.0.jpg"></p>
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<footer style='font-size:18px'>
Avalanche Breakdown$\to$Higher Concentration$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$Voltage Regulator$\to$Problem$\to$Photodiode$\to$<span style="color:blue">Light Emitting Diode: LED</span>$\to$Solar Cell
</footer>

<p><Success style="float:center;text-align:center;font-size:28px;" ><B>Special Purpose P-N Junction</B></Success></p>
<p><Primary style="float:center;text-align:center;font-size:24px;"><B>Solar Cell</B></Primary></p>
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<p>$h\nu > E_g$</p>
<p>$e-h \hspace{2mm}$ Pair generation</p>
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<p>Pairs which are generated are swpet away by the Electric field.</p>
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<p>The voltage which is generated is called as a open circuit voltage</p>
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<p>0.6 volts.</p>
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<p><img alt="image" src="/subject-images/iitpal/image/physics-class-12-unit-14-chapter-06-special-purpose-p-n-junction-physics-l-6_8-9itcu1voaye-003.jpg"></p>
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Avalanche Breakdown$\to$Higher Concentration$\to$I-V Curve Showing Avalanche and Zener Breakdown$\to$Voltage Regulator$\to$Problem$\to$Photodiode$\to$Light Emitting Diode: LED$\to$<span style="color:blue">Solar Cell</span>
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