Semiconductors ECE Spring 2022 IIIT Hyderabad Asst. Prof. A. Sarje Review (EM) • Gauss Law & Divergence Theorem • Potential between two points • Poisson’s Equation & Laplace equation • Solution to Wave Diļ¬erential equation (HW) Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Some exceptions • Sn, Pb are metals • Pure C (diamond) is insulator • AlN and BN are insulators Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Some Examples • • Today we find Semiconductors Everywhere • Generating Electricity to Using Electricity • Generating Light/Sound to Detecting Light & Manipulating Light/Sound • Kitchen, Laboratory, Hospitals/OT, Spaceships, Oil rig, Sub marine, Automobile, Home appliances, IOT…. Endless list Devices • Photo diodes, solar cells, Optical Displays (OLED, QD-based), LED • Power devices: SiC based, Thyristors • Laser diodes, photo couplers • Wave guides, Transistors Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Lead (IV) - VI group PbS Lead sulfide : oldest semiconductor known • • • Infrared detectors Photo optic applications Slip property modifier used in friction industry Lead Telluride • Low bandgap, used as thermoelectric • Infrared detection and imaging • Solar cells. Lead Selenide • Infrared detectors for thermal imaging • Gas analysis • Hot spot detection • Industrial process and quality control • Defense applications http://www.teledynejudson.com/prods https://virtual-museum.soils.wisc.edu/displays/ https://virtual-museum.soils.wisc.edu/display/halite Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Electro-optic Modulator LiNbO3 • Human made (not natural) • Electro-optic modulator • Changes refractive index when electric field applied wikipedia.com http://www.pmoptics.com/catvmodulator.html Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Quantum Dots Single Electron Transistor Q LED Power Devices Quantum LED screen Solar Power Harvesting Sub Nano Transistors Quantum Laser Devices Organic LED Display Silicon Monsoon 2020 Principles of Semiconductor Devices http://hyperphysics.phy-astr.gsu.edu/hbase/Solids/sili.html Physics-and-radio-electronics.com Dr. A. Sarje, IIITH Semiconductor classification • Purity: Semiconductor material have to have purity (Si: 1 impurity in 10^6 i.e. <10^16/cc ) • Intentional doping to change property: 10^14/cc to 10^22/cc • Semiconductor have to pure (no impurities). Only certain desired impurities called DOPANTS are added to control its conductivity. • Materials classification • Amorphous • Crystalline • Polycrystalline Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Crystals • Periodic Array of atoms • They occur naturally also. DIY Fun project Grow your own crystals https://sciencenotes.org/how-to-grow-crystals/ Monsoon 2020 Principles of Semiconductor Devices https://sciencenotes.org/ Dr. A. Sarje, IIITH Crystals Chocolate Silicon Quartz Common Salt Monsoon 2020 Principles of Semiconductor Devices chocolatealchemy.com https://www.pv-magazine.com/silicon-crystals-and-ingots-used-for-solar-cell-manufacturing/ www.lasenor.com Dr. A. Sarje, IIITH Crystal of Naica Mexico http://www.geologypage.com/2016/06/cave-of-crystals-giant-crystal-cave.html Monsoon 2020 Principles of Semiconductor Devices Dr. A. Sarje, IIITH Silicon Boule • Silicon is one of the most abundant elements on this earth Silicon Boule • Purified silicon is melt and crystallised into huge silicon crystal by seeding. Czochralski process. • https://www.youtube.com/watch? v=cYj_vqcyI78 Silicon Furnace yiwafer.com Monsoon 2020 Principles of Semiconductor Devices www.tf.uni-kiel.de Dr. A. Sarje, IIITH