Explanation:

P-type semiconductor:

When a small quantity of impurity atoms such as aluminum, boron or gallium are added to pure semiconductor materials such as silicon or germanium, it creates a material called P-type semiconductor. P-type semiconductor is created by doping a small quantity of trivalent impurity atoms in the pure semiconductor material. In P-type semiconductor, the majority carriers are holes and the minority carriers are electrons.

Working principle:

When a small quantity of aluminum is added to a silicon or germanium crystal, a P-type semiconductor is created. The aluminum atoms have only three valence electrons compared to the four valence electrons of the silicon or germanium atoms. This creates a hole in the crystal lattice structure of the silicon or germanium material.

As a result, the P-type semiconductor material has an excess of holes or positive charge carriers. When a voltage is applied across the P-type semiconductor material, these holes act as charge carriers and move towards the negative terminal of the voltage source.

Applications:

P-type semiconductor materials are widely used in the fabrication of electronic devices such as transistors, diodes, and integrated circuits. P-type semiconductors are used in the base layer of bipolar junction transistors (BJTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs).

Conclusion:

Hence, the addition of a very small quantity of aluminum to a silicon or germanium crystal makes it a P-type semiconductor material. P-type semiconductors have an excess of holes or positive charge carriers, and they are widely used in electronic devices.