(saturation).
When the junction barrier is strengthened, current
through the diode is reduced to such a small value that it can be
disregarded (cutoff).
(2) To better understand the operation of a junction diode, compare its
operation to that of an electron-tube diode.
Figure 1-3 shows the
comparison. When battery Ebb is connected as in A, the positive on the
plate attracts the negative electrons emitted by the cathode. Current
flow is indicated by the meter.
Figure 1-3.
Comparison of electron-tube diode with junction diode.
(3) In B of figure 1-3, the positive charge of the battery on the P-type
material repels the positive charges in the P material toward the
junction.
Likewise, the negative charge of the battery on the N-type
material repels the negative charges in the N material toward the
junction.
Since unlike charges attract, the opposing charges
effectively combine, weakening the opposition of the junction barrier.
When the battery is connected in this manner, it aids the flow of
current across the junction, and the diode is said to be forward
biased.
309 L1
6
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