1. The problem is to understand the basic concept of semiconductors. 2. Semiconductors are materials with electrical conductivity between conductors (like metals) and insulators (like glass). 3. The conductivity of semiconductors can be controlled by adding impurities, a process called doping. 4. Important rules: - Pure semiconductors have moderate conductivity. - Doping introduces free charge carriers: electrons (n-type) or holes (p-type). 5. This allows semiconductors to be used in electronic devices like diodes and transistors. 6. In summary, semiconductors are materials whose electrical properties can be precisely controlled for use in electronics.