The barrier potential of the PN junction diode is caused due to migration of charges across the junction. This potential is due to the differential charge density, across the junction .If the cross section area of the junction is increased, the number of charge carriers is increased and the barrier potential must increase.But practically(even theoretically) its not possible to get more than 0.6V. Why this is so ?
2007-08-11 16:33:10 · 2 answers · asked by Chander's 1 in Science & Mathematics ➔ Physics
Increasing the cross-section of the junction does not affect the charge density. The total charge in the junction is increased because the volume of the space-charge region (area times depletion-depth) is larger, but the charge density (charge per unit volume), which determines the potential, is fixed by the doping of the semiconductors and does not change.
2007-08-11 18:20:10 · answer #1 · answered by gp4rts 7 · 0⤊ 0⤋
Increasing the cross section of the interface increases the number of charges but not the charge density.
For any particular diode the amount of potential barrier is a function of the type of material used in maufacture of the junction.
Silicon and germanium have different barrier potential....which is determined at the manufacturing process.
2007-08-12 00:00:20 · answer #2 · answered by Anonymous · 1⤊ 0⤋