A quantum well is a structure in quantum mechanics that confines particles, such as electrons or holes, in one spatial dimension. This confinement leads to quantized energy levels, creating a potential well in which the particles are restricted to move.
In semiconductor physics and device engineering, quantum wells are commonly used to create electronic or optical devices. These structures are typically thin layers (often on the order of nanometers) sandwiched between layers of a different material. The quantum confinement effect arises because the energy levels for particles within the well become quantized due to their confinement in one dimension.
The quantization of energy levels in a quantum well has several important implications:
Energy levels: Only certain discrete energy levels are allowed for particles within the well. The separation between these energy levels depends on the characteristics of the well, such as its width and the properties of the materials involved.
Wavelength restriction: In the case of electrons, for example, their motion is confined in one dimension, leading to quantized energy levels. This restriction on energy levels also translates into a restriction on the possible wavelengths of light that can be emitted or absorbed by the electrons.
Optoelectronic devices: Quantum wells are crucial components in various optoelectronic devices, such as quantum well lasers and quantum well infrared photodetectors. The quantization of energy levels allows for precise control over the emission or absorption of photons.
Tunneling: Quantum wells also exhibit quantum tunneling phenomena, where particles can pass through energy barriers that classical physics would consider impenetrable.
The term quantum well is used in different contexts, including semiconductor physics, quantum optics, and quantum information processing, reflecting its versatile applications in various fields of physics and technology.