What Is Tellurium?

Tellurium is a brittle, silvery-white metalloid element occupying Group 16 of the periodic table, with atomic number 52 and the chemical symbol Te. Discovered in 1782 by the Hungarian mineralogist Franz-Joseph Müller von Reichenstein and named by Martin Heinrich Klaproth in 1798, it occupies an intermediate position between metals and nonmetals and exhibits an intrinsically p-type semiconductor character. Its narrow bandgap of approximately 0.33 eV and high carrier mobility place it among a small group of elemental semiconductors that attract sustained interest in microelectronics, energy conversion, and optoelectronics research.

Tellurium is relatively rare in the Earth's crust, more scarce than gold, and is recovered primarily as a byproduct of copper refining. Its electrical and thermoelectric properties are strongly anisotropic, reflecting the chiral one-dimensional atomic chains that form its crystal structure. This structural character makes tellurium distinct from cubic semiconductors such as silicon and germanium and gives rise to unusual optical and transport phenomena.

Semiconductor Properties and Electronic Behavior

As a narrow-bandgap p-type semiconductor, tellurium exhibits Hall mobilities reaching 250 cm²/V·s in thin-film configurations, a figure that supports practical transistor fabrication. Research published in Nature on selenium-alloyed tellurium oxide demonstrates that tellurium-based oxides enable amorphous p-channel transistors compatible with low-temperature processing, expanding their utility in flexible and large-area electronics. The anisotropic band structure allows charge transport to be tuned by controlling crystal orientation, and low Schottky barrier heights at metal contacts reduce parasitic resistance in device configurations.

Two-dimensional and quasi-one-dimensional forms of tellurium have attracted considerable recent attention. Van der Waals layered structures of elemental tellurium can be exfoliated to few-atom thickness, producing material with tunable bandgaps and preserved carrier mobility. These thin-film and nanostructured forms are under investigation for field-effect transistors, photodetectors, and complementary metal-oxide-semiconductor (CMOS)-compatible circuits.

Thermoelectric Applications and Telluride Compounds

The most commercially significant role of tellurium is as a constituent of thermoelectric materials, principally bismuth telluride (Bi₂Te₃) and its alloys. Bismuth telluride operates near room temperature with a dimensionless figure of merit (ZT) that makes it the dominant material for solid-state cooling and low-grade waste heat recovery. A review of bismuth telluride and its alloys as thermoelectric materials confirms that p-type and n-type variants can be combined in modules achieving conversion efficiencies above 8%, substantially exceeding conventional commercial modules. Lead telluride (PbTe) extends the useful temperature range to 300-600 °C and is employed in thermoelectric generators for deep-space probes and industrial waste heat systems.

The cost and relative scarcity of tellurium impose real constraints on large-scale deployment of bismuth telluride devices, motivating research into reduced-tellurium or tellurium-free alternatives while the materials science of known tellurides continues to be refined.

Photovoltaic and Optical Uses

Cadmium telluride (CdTe) thin-film solar cells represent the largest volume application of tellurium by mass. CdTe has a direct bandgap near 1.45 eV, closely matched to the solar spectrum, and thin-film panels based on this material have achieved commercial module efficiencies exceeding 19%. Tellurium-based materials also find use in infrared optics, where mercury cadmium telluride (HgCdTe, or MCT) is the principal detector material for mid-wave and long-wave infrared sensing from 3 to 15 micrometers. A 2025 review of tellurium-based materials for nanoelectronics outlines how CdTe and HgCdTe continue to set the baseline against which new tellurium compound device concepts are measured.

Applications

Tellurium has applications in a range of fields, including:

• Thermoelectric cooling and power generation using bismuth telluride modules
• Thin-film photovoltaics based on cadmium telluride absorber layers
• Infrared photodetectors using mercury cadmium telluride for thermal imaging
• Phase-change memory materials, where tellurium alloys store data as amorphous or crystalline states
• Metallurgical additives that improve the machinability of copper and stainless steel