cadmiumtellurid

Cadmium telluride, with the chemical formula CdTe, is a binary compound semiconductor in the II–VI family. It forms a crystalline solid with a zinc blende (sphalerite) structure at room temperature and is typically produced as polycrystalline thin films or bulk crystals.

CdTe has a direct band gap of about 1.44 eV at room temperature, placing it in the visible light range for efficient photon absorption. It also exhibits a high optical absorption coefficient, on the order of 10^5 cm−1, which allows very thin absorber layers in devices.

Growth and processing methods vary by form. Bulk crystals are grown by techniques such as the traveling heater method or vapor transport, while thin films are deposited by methods including close-spaced sublimation and various vapor- and solution-based techniques. Doping can tailor its electrical type: copper and cadmium vacancies tend to produce p-type material, whereas donor dopants such as chlorine, indium, or gallium can enable n-type conduction under suitable processing.

Cadmium telluride is widely used in photovoltaic devices, especially CdS/CdTe thin-film solar cells, where a CdS window layer is paired with CdTe to form a p–n junction. The material’s strong absorption allows relatively thin CdTe layers, typically a few micrometers, in efficient solar cells. Beyond photovoltaics, CdTe is used in certain radiation and infrared detectors, including CdZnTe-based detector configurations.

Safety and environmental concerns center on cadmium toxicity. Proper handling, encapsulation, and disposal are important to minimize environmental release, and regulatory controls apply to cadmium-containing devices.