The reason you can’t measure potential is Hidden built-in voltage due to ohmic contact forming a Schottky diode at the semiconductor metal junction (as shown in the band diagram). There is a built-in voltage even in the absence of current.

Why can’t you measure barrier potential with a voltmeter?

We cannot measure the barrier of the PN junction by connecting a sensitive voltmeter to its terminals because in the depletion region, there are no free electrons and holes, and in the absence of forward bias, the PN junction Provides unlimited resistance.

Can we measure the barrier with the help of a voltmeter?

No, it cannot be measured with a voltmeter. The barrier potential is less than 0.2 V for germanium diodes and less than 0.7 V for silicon diodes.

How do we measure barrier potential?

an ordinary Voltmeter Having a finite input impedance, it just means that, to measure the voltage across it, there must be some (tiny) current flowing through the voltmeter. Therefore, measuring the built-in potential of a diode with a voltmeter requires the built-in potential to « drive » a (tiny) current through the voltmeter.

Can we measure the potential difference with a voltmeter?

Potential difference is measured using a device called a voltmeter …however, unlike an ammeter, you must connect a voltmeter in parallel to measure the potential difference between components in a circuit.

Explain why the pn junction contact potential cannot be measured with a voltmeter

32 related questions found

How to calculate resistance?

If you know the total current and voltage of the entire circuit, you can use Ohm’s law to find the total resistance: R = V / I. For example, a parallel circuit has a voltage of 9 volts and a total current of 3 amps. Total resistance RT = 9 volts / 3 amps = 3 Ω.

How to read a voltmeter?

The reading of the voltmeter can be determined by using the current value in the circuit to find the potential difference across the 2Ω resistor. V=IR, where V is the potential difference across the resistor R through which the current I flows. An ammeter is connected in series with the circuit.

How to measure built-in potential?

The built-in potential (at 300 K) is equal to fi = kT/q liter(1016 x 9 x 1017/ni2) = 0.77 V, using kT/q = 25.84 mV and ni = 1010 cm-3. The built-in potential (at 100°C) is equal to fi = kT/q ln(1016 x 9 x 1017/ni2) = 0.673 V, using kT/q = 32.14 mV and ni = 8.55 x 1011 cm-3 (from Example 20) .

How to calculate barrier voltage?

Transcribe image text: Calculate the barrier voltage of a pn junction diode if the intrinsic concentration is 1.5 times the notation 10^10 cm^-3. Donor concentration. N_D=7 times notation 10^16 cm^-3. And the receptor concentration N_A=5 times the symbol 10^15 cm^-3.

How to measure pn junction?

How can we experimentally measure the built-in voltage of a pn junction at thermal equilibrium?use Voltmeter between anode and cathode, it injects current through the terminals, so balancing doesn’t still happen. For zero current, measure zero voltage.

Is it possible to measure the voltage across the barrier?

Is it possible to measure the voltage across the barrier with a voltmeter? Explanation: The contacts of the voltmeter have some resistance and cannot accurately measure the voltage across the potential barrier.Therefore, it not measurable voltage across the barrier.

How to calculate the barrier of a diode?

The potential barrier of a pn junction is given by the following relationship,Vbi = Vt ln(Na*Nd/ni²) Ge is typically 0.2V and Si is 0.8V.

Can it cross the barrier of the pn junction?

We cannot measure potential obstacles The PN junction is measured by connecting a sensitive voltmeter to its terminals, because in the depletion region, there are no free electrons and holes, and in the absence of forward bias, the PN junction provides infinite resistance.

Is the diode unipolar or bipolar?

According to some sources, the diode is Bipolar device Because it has both electrons and holes as carriers.

How do you measure contact potential?

contact potential not measurable Because when in contact with the junction, a potential is formed across the contact which is used to remove the contact potential. The contact potential also separates the bands, with a higher conduction band on the p-side. This is necessary to make the Fermi level constant.

Can we measure the barrier of a pn junction by placing a sensitive voltmeter across the terminals of the pn junction?

What we can’t measure are potential obstacles A PN junction is implemented by connecting a sensitive voltage regulator across its terminals, because in the depletion region, there are no free electrons and holes, and in the absence of forward bias, a PN junction provides infinite resistance.

What is the barrier voltage?

« The barrier voltage is The amount of electromotive force required to start the current through the PN junction. The barrier voltage of silicon is typically between 0.5 – 0.7 volts. The barrier voltage of germanium is typically between 0.2 – 0.3 volts. « 

Is a zener diode a diode?

Zener diodes are Silicon semiconductor device that allows current to flow Either forward or reverse. The diode consists of a special heavily doped pn junction designed to conduct reversely when a specific specified voltage is reached.

What is the barrier voltage?

The negative charge formed on the p-side of the pn junction is called the negative barrier voltage, and the positive charge formed on the n-side of the pn junction is called the positive barrier voltage.This total charge formed The pn junction is called barrier voltage, barrier potential or junction barrier.

Can the built-in voltage be measured?

Built-in voltage can not Measured by connecting the probe externally to the device.

What is the built-in voltage?

Built-in voltage is simple Fermi level difference between p-type and n-type semiconductors before bonding.

What is the voltage of the germanium diode?

When the voltage correctly applied to the diode reaches 0.3V. Silicon diodes require more voltage to conduct current; 0.7 volts are required to create forward bias in silicon diodes.

What is the principle of a voltmeter?

The main principle of a voltmeter is It has to be connected in parallel where we want to measure the voltage. The parallel connection is used because the voltmeter is constructed in such a way that it has a very high resistance value.

What does a voltmeter measure?

Voltmeter, measuring instrument DC or AC voltage on scale Usually measured in volts, millivolts (0.001 volts), or kilovolts (1,000 volts).

What is the resistance of the voltmeter shown in the circuit?

Let the resistance of the voltmeter be RV. So option B is correct. NOTE: Voltmeters are devices with high resistance to allow as little current to flow as possible, and are always connected in parallel to prevent heating of the circuit.