Quantum Wells

A quantum well is a two-dimensional structure formed when two layers of different materials are placed together. The two layers are usually semiconductors, such as gallium arsenide, separated by an ultrathin barrier of another material, such as aluminum arsenide. The barrier is typically only a few nanometers thick, effectively trapping electrons within the well. Quantum wells are used in a variety of electronic devices, such as LEDs, lasers, photodetectors, and transistors. When an electron is confined to a quantum well, it behaves differently from a free electron, due to the effects of quantum mechanics. A quantum well acts as a confining potential energy, which affects the energy levels of the electron. These energy levels are quantized, meaning that the electron can only occupy certain energy levels, known as quantum states. This quantization of energy levels leads to a number of interesting properties, such as a greater mobility of the electrons within the well and a greater sensitivity to external fields. Quantum wells are also used in optoelectronic devices, such as LEDs and lasers. In these devices, electrons and holes are injected into the quantum well, where they recombine and emit light. The wavelength of the emitted light depends on the width of the quantum well, allowing for the tuning of the device to a specific frequency. Quantum wells are also used in transistors, where the electrons are confined to a quantum well in order to increase the transistor’s switching speed and efficiency.