MCQ Detailed View

The two elements most commonly used for making transistors are silicon (Si) and germanium (Ge). Both of these elements belong to Group 14 (Carbon Group) of the periodic table and are well-known as semiconductors. Their electrical conductivity lies between that of a conductor and an insulator, and this property can be controlled by adding impurities, a process known as doping.

The first practical transistors, invented in 1947 at Bell Laboratories by John Bardeen, Walter Brattain, and William Shockley, were made using germanium. Germanium has high electron mobility, which makes it suitable for fast switching applications. However, it also has limitations such as sensitivity to temperature, which reduces its stability in practical electronic circuits.

Silicon soon became the preferred material for transistors. It has a wider band gap (1.1 eV) compared to germanium (0.66 eV), making it less sensitive to temperature changes and more efficient in handling high voltages. Additionally, silicon forms a natural oxide layer (silicon dioxide, SiO₂) which is crucial for the fabrication of integrated circuits and microchips. This oxide layer provides excellent insulation and makes large-scale semiconductor manufacturing possible.

Other elements such as boron, aluminium, iridium, or tungsten are not used as the base materials for transistors, although boron and aluminium may be used as dopants to modify semiconductor properties. The backbone of nearly all modern electronics, from computers to smartphones, depends on transistors made primarily of silicon, with germanium still used in some specialized applications.

Therefore, the correct answer is Silicon and Germanium, which remain the foundation of semiconductor technology and modern electronic devices.