If a battery is connected across the crystal in the direction shown in Fig. 31, holes are repelled from the positive end of the crystal and are caused to drift towards the junction; and electrons are repelled from the negative end of the crystal and also drift towards the junction. This drift of holes and electrons towards the junction reduces both the width of the depletion layer and the height of the potential barrier, and the junction is said to be forward biased. The reduction in the height of the potential barrier allows majority charge carriers of lower energy to cross the junction and since the minority charge carrier current remains constant, there is a net majority charge carrier current across the junction from the P-type region to the N-type region. This current increases very rapidly with increase in the forward bias voltage.
The holes drifting through the P-type region towards the P-N junction may be considered to have been injected by the positive terminal of the battery. Some of these holes may recombine with electrons diffusing across the junction in the other direction and so the hole current across the junction is slightly less than the injected hole current. After they have passed across the junction the holes recombine with the excess electrons in the N-type region and the electrons that have not recombined cross the junction. The total current is the sum of the electron and hole currents and is constant throughout the crystal. The current enters the P-type region as a hole current and leaves the N-type region as an electron current.
Notes:
| depletion layer | обедненный (истощенный) слой |
| to be biased | быть смещенным |
| potential barrier | потенциальный барьер |
| to drift | перемещаться |