| semiconductor | |
|---|---|
| Name | Semiconductor |
| Caption | Crystalline silicon, a prototypical semiconductor |
| Type | Material |
| Composition | Elemental (e.g., Silicon) or compound (e.g., Gallium arsenide) |
| Applications | Electronics, Photonics, Computing |
| Discovered | Mid-20th century (modern solid-state devices) |
| Notable institutions | Bell Laboratories, Massachusetts Institute of Technology, IBM, Intel |
semiconductor
A semiconductor is a class of crystalline and amorphous materials whose electrical conductivity lies between that of conductors and insulators. In the context of Quantum Physics, semiconductors are central because their electronic, optical, and thermal properties derive from quantum-mechanical behavior of electrons in periodic potentials and engineered structures, enabling modern electronics and quantum-enabled technologies.
Semiconductors serve as a practical laboratory for testing and exploiting principles of Quantum mechanics and Solid-state physics. Devices such as transistors and laser diodes manifest quantum confinement, tunneling, and discrete energy states predicted by theory. Major research institutions—Bell Laboratories, IBM Research, Stanford University, and the California Institute of Technology—have used semiconductor systems to probe many-body effects (e.g., quantum Hall effect) and to develop platforms for quantum computing such as silicon qubits and spin qubit architectures. Semiconductor heterostructures and nanostructures bridge fundamental quantum research and industrial applications in firms like Intel and Nvidia.
Semiconductor behavior is governed by quantum properties of electrons and holes in periodic lattices described by Bloch's theorem and band theory. Phenomena such as quantum tunneling, quantum confinement, and wavefunction coherence determine transport and optical response. Many-body quantum treatments (e.g., Bardeen–Cooper–Schrieffer theory for superconductivity in doped semiconductors or Fermi–Dirac statistics for carriers) inform device operation. Experiments at laboratories including CERN-adjacent groups and national labs such as Lawrence Berkeley National Laboratory explore excitonic effects, electron spin resonance, and decoherence relevant to quantum information science.
Electronic band structure—valence and conduction bands, band gap, and effective mass—directly results from quantum solutions of electrons in periodic potentials. Semiconductors like silicon (indirect band gap) and Gallium arsenide (direct band gap) differ in optical transition strengths and carrier dynamics, influencing applications from photovoltaic cells to light-emitting diodes. Charge carriers are described as quasiparticles: electrons and holes whose populations obey Fermi–Dirac distribution; key concepts include carrier lifetime, mobility, recombination (radiative and nonradiative), and drift-diffusion under applied fields examined in texts by authors such as Charles Kittel and Neil W. Ashcroft.
Semiconductor quantum devices span classical-to-quantum regimes. The pn junction and MOSFET are foundational for classical computing in companies like Intel and AMD. Quantum-specific devices include single-electron transistors, quantum dots used in quantum dot lasers and single-photon sources, and superconductor–semiconductor hybrid systems for Majorana research pursued at institutions like Microsoft Research and ETH Zurich. Semiconductors underpin photodetectors, solar cells (e.g., silicon photovoltaics), and optoelectronic integration in telecommunications by firms such as Corning Incorporated and Applied Materials.
Materials science for semiconductors encompasses elemental crystals (silicon, germanium), III–V compounds (gallium arsenide, Indium phosphide), and emerging two-dimensional materials like graphene and transition metal dichalcogenides (e.g., MoS2). Doping with donors or acceptors (phosphorus, boron) introduces shallow impurity levels, a process industrialized by techniques such as ion implantation and diffusion in fabs operated by TSMC and Samsung Electronics. Nanostructuring—quantum wells, wires, and dots grown by molecular beam epitaxy at facilities such as University of California, Santa Barbara—creates size-quantized energy levels exploited in lasers, sensors, and proposed quantum processors.
Quantum phenomena in semiconductors are characterized by spectroscopic and transport measurements. Techniques include photoluminescence, time-resolved pump–probe spectroscopy, angle-resolved photoemission spectroscopy (ARPES) at synchrotron centers like SLAC National Accelerator Laboratory, and scanning probe methods such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Low-temperature, high-magnetic-field measurements reveal quantum oscillations and the fractional quantum Hall effect, while electron spin resonance and single-shot readout are employed to probe qubit states in silicon devices developed at groups including Delft University of Technology and University of New South Wales.
The modern semiconductor era grew from mid-20th-century advances: the invention of the transistor at Bell Laboratories and subsequent development of the integrated circuit by inventors like Robert Noyce and Jack Kilby. Quantum theory provided the explanatory framework; band theory and semiconductor physics matured through work by scientists such as William Shockley and Walter Brattain. Industrialization led to the Silicon Valley ecosystem and global supply chains dominated by firms like Intel, TSMC, and Samsung Electronics. Semiconductors have reshaped national economies, defense capabilities, and social life, prompting policy focus on domestic manufacturing and research stability by governments and institutions worldwide.
Category:Semiconductors Category:Quantum physics