about 0.2 V
more at higher temps
any closer look at the specific diodes spec sheet
dopeants vary
0.3v as opposed to the silicon 0.6v
== 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.
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.
barrier potential P0=(kT/q)*ln(Na*Nd/Ni^2) when T ↑, P0↑.
Yes, it varies inversely, i.e. as temperature increases the barrier potential decreases. It decreases by 2mV for degree Celsius rise of temperature.
Potential barrier of silicon is 0.7, whereas potential barrier of germanium is 0.3
0.3 volt
0.3v as opposed to the silicon 0.6v
Due to variation in energy gap between valance band and conduction band....
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.
== 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.
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
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.
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.
The potential across a pn junction is called potential barrier because majority charge carriers have to overcome this potential before crossing the junction.
Breakdown voltage is far greater than barrier potential. silicon:- break-down voltage :- 5v - 450 v barrier potential ;- 0.5v to 0.7 V
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.