Introduction Level of integrations in IC’s : Source: wikipedia ULSI, WSI, SoC and 3D-IC Conductor - Low Resistance SemiConductor - Resistance changes Insulator - High Resistance Karl Ferdinand Braun developed the crystal detector , the first semiconductor device , in 1874. SemiConductor A semiconductor material has an electrical conductivity value falling between that if a conductor , such as metallic copper, and an insulator , such as glass. Its conducting properties may be altered in useful ways by introducing impurities (" doping ") . Semiconductor - Types Intrinsic (pure) Extrinsic (Doped) N type Ptype Intrinsic semiconductor Donor atoms (n-Type Semiconductor) Acceptor atoms (p-Type Semiconductor) Group IV semiconductors Silicon , Germanium Phosphorus , Arsenic , Antimony Boron , Aluminium , Gallium Group III–V semiconductors Aluminum phosphide , Aluminum arsenide , Gallium arsenide , Gallium nitride Selenium ...