Contents
How is built-in potential developed in a PN junction?
P-n junctions are formed by joining n-type and p-type semiconductor materials, as shown below. Since the n-type region has a high electron concentration and the p-type a high hole concentration, electrons diffuse from the n-type side to the p-type side. A “built-in” potential Vbi is formed at the junction due to E.
What is band gap energy of pn junction diode?
The band gap of a semiconductor is the minimum energy required to excite an electron that is stuck in its bound state into a free state where it can participate in conduction. The band structure of a semiconductor gives the energy of the electrons on the y-axis and is called a “band diagram”.
Is contact potential and built-in potential same?
Thus, an electric field is formed going from the n-side to the p-side and there is a built-in potential, from the p to the n side. This potential is called the junction potential or contact potential.
What is the forbidden energy gap?
Forbidden energy gap, also known as band gap refers to the energy difference (eV) between the top of valence band and the bottom of the conduction band in materials. Current flowing through the materials is due to the electron transfer from the valence band to the conduction band.
What factor s do as the barrier potential of a pn junction depends on?
Barrier potential depends on the material used to make p-n junction diode (whether it is Si or Ge). It should also depend on the amount of doping due to which the number of majority charge carriers will change. Also, it depends on temperature due to which the number of minority carriers will change.
Why is the p-n junction called a diode?
Since the p-n junction demonstrates such a unipolar (rectifying) response to the applied voltage it is called a p-n diode and is denoted in circuit diagrams as a following symbol: The current voltage (IV) characteristic for the diode is rectifying and is very different from that for a resistor.
Every procedure I’ve encountered states that the energy of an emitted photon (and by extension the potential across the semiconductor’s band gap) is equal to the threshold voltage multiplied by the elementary charge.
How does forward bias affect the p-n junction?
When we apply forward bias (positive voltage to p-type, negative voltage to n-type) it effectively reduces the built-in voltage. When we apply reverse bias (positive voltage to n-type, negative voltage to p-type) it effectively increases the built-in voltage.
What is the built in potential of a p-n junction?
Calculate the built-in potential of the p-n junction at 400 K. Similarly, the built-in potential at 400 K equals: where the instrinsic carrier density at 400 K was obtained from example 2.4.b 4.2.4. Forward and reverse bias We now consider a p-n diode with an applied bias voltage, Va.