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Why potential across pn junction is called potential barrier?
The potential across a pn junction is called potential barrier because majority charge carriers have to overcome this potential before crossing the junction.
Why does a diode not conduct until the cut in voltage is reached?
Cut in voltage is the minimum voltage required to overcome the barrier potential. In other words it is like trying to push a large boulder....it may not be possible to push a large boulder by one person but it may be done if 2 or more people try to push it together depending on the size of the boulder.....similarly....the charge carriers in the barrier region have a potential energy of about 0.6V for Silicon and about 0.2V for Germanium. so in order for the diode to conduct, it is required to overcome the potential of the charge carriers in the junction barrier region and hence only if a potential more than that of the barrier potential (cut off voltage) is applied, then electrons flow past the junction barrier and the diode conducts.
What would cause the barrier potential to decrease from 0.7v to 0.6v?
The forward voltage of a semiconductor junction, silicon or germanium, changes by -2mV for every rise in temperature of 1 degree C, so your friend is correct
What is potential barrier factor?
Potential barrier is the energy inserted in order to go against the passage of electron.
Why germanium and silicon are considered as best semiconductors?
actually diamond should be much better, if fabrication issues can be solved, it is faster and will operate up to 600ºC junction temperature. Silicon is limited to 150ºC junction temperature and Germanium is limited to 50ºC to 60ºC. Germanium was originally used because it was easiest to purify and process. Silicon is the cheapest material now, it comes from sand and there is no shortage of that.
Compare the characteristics of a silicon and germanium diode?
Potential barrier of silicon is 0.7, whereas potential barrier of germanium is 0.3
Why silicon has more barrier potential than germanium?
Silicon has a larger band gap than germanium, leading to a higher barrier potential. This is due to the differences in the electronic structure of these two materials. Silicon's larger band gap means that it requires more energy to move electrons across the junction, resulting in a higher barrier potential compared to germanium.
Which is greater the breakdown voltage or the barrier potential?
Breakdown voltage is far greater than barrier potential. silicon:- break-down voltage :- 5v - 450 v barrier potential ;- 0.5v to 0.7 V
What is the typical value of the barrier potential for a germanium diode?
The typical value of the barrier potential for a germanium diode is around 0.3 to 0.4 volts. This barrier potential is the voltage required to overcome the potential barrier at the junction of the diode and allow current flow in the forward direction.
Why germanium has less barrier potential than silicon?
germanium has great intrinsic concentration at room temperature,hence conduction is great in germanum compared to silicon, and resistance decreases in germanum and hence built in potentail also less in germanum compared to silicon.built in potential of silicon is 0.7v built in potential of germanum is 0.3v. 1)intrinsic concentration of germanium at room temperature is 2.5*10^13 atoms/cm^3. 2)intrinsic concentration of silicon at room temperature of 300k is 1.5*10^10 atoms/cm^3.
What is the cut in voltage of germanium and silicon diodes?
cut in voltage *** for silicon is 0.7volts and that for germanium is 0.3volts.According to Millman and Taub, "Pulse, Digital and Switching Waveforms", McGraw-Hill 1965, the cutin (or offset, break-point or threshold) voltage for a silicon diode is 0.6, and 0.2 for germanium.Breakdown voltage is another thing entirely. It is the reverse voltage at which the junction will break down.
What would cause the barrier potential to decrease from 0.7 V to 0.6 V?
The barrier potential may depend on the exact material; but you can't normally change that. It may also depend on temperature.Also, such a barrier potential is not fixed at some value (like 0.7 V); however, it's often close enough that you can consider it to be constant. But actually, the barrier potential depends on the current. At higher currents, the potential is slightly higher.
What is meant by 0.3 volts for germanium and 0.7 volts for silicon?
== When we make a semiconductor junction (a p-n junction), the electric fields force charges to shift creating what is called a depletion region. This depletion region forms a potential barrier across the junction. This potential barrier has a voltage associated with it, and that voltage is 0.3 volts (approximately) for germanium semiconductor material, and 0.7 volts (approximately) for silicon semiconductor. The terms we apply to this barrier potential are the built-in voltage (or potential), junction voltage (or potential), and contact potential. Use the link below to check facts and review some other closely related material.
What happens to the barrier potential when the temperature increases?
When the temperature increases, the barrier potential in a semiconductor diode decreases. This is due to the increase in carrier density at higher temperatures, which results in more charge carriers being available to pass through the barrier. Ultimately, this leads to a lower resistance across the diode and a decrease in the potential barrier.
Why potential across pn junction is called potential barrier?
The potential across a pn junction is called potential barrier because majority charge carriers have to overcome this potential before crossing the junction.
What is the typical value of the barrier potential for a silicon diode?
Forward biase the given diode by using a Variable resistor in the circuit. By adjusting the value of variable resistor you will adjust the voltage being applied to junction diode. First adjust the resistance such that no(negligble) current flows through the circuit. Now start decreasing the value of resistance. Note the voltage across resistor(Vr) when current just starts flowing through the circuit. Then Potential barrier of diode will be: Vb=V-Vr Vb:Barrier Potential V:Battery Voltage Vr:Voltage Drop across resistance when current just starts flowing through the circuit.
Why does a diode not conduct until the cut in voltage is reached?
Cut in voltage is the minimum voltage required to overcome the barrier potential. In other words it is like trying to push a large boulder....it may not be possible to push a large boulder by one person but it may be done if 2 or more people try to push it together depending on the size of the boulder.....similarly....the charge carriers in the barrier region have a potential energy of about 0.6V for Silicon and about 0.2V for Germanium. so in order for the diode to conduct, it is required to overcome the potential of the charge carriers in the junction barrier region and hence only if a potential more than that of the barrier potential (cut off voltage) is applied, then electrons flow past the junction barrier and the diode conducts.
