What Is Antimony?

Antimony is a metalloid element with atomic number 51 and the chemical symbol Sb, positioned in Group 15 of the periodic table alongside nitrogen, phosphorus, arsenic, and bismuth. It exhibits properties intermediate between metals and nonmetals: it conducts electricity poorly at room temperature, forms brittle crystalline structures, and can behave as either a metal or a nonmetal depending on its chemical environment and bonding configuration. Antimony has been known to human civilization for thousands of years in the form of its sulfide ore stibnite, but its modern engineering relevance derives from its role as a semiconductor dopant, a component in compound semiconductors and phase-change materials, and a flame-retardant additive in plastics and electronics packaging.

In electronics, antimony is primarily encountered as an n-type dopant in silicon and germanium, and as a constituent of binary and ternary compound semiconductors. Its position in Group 15 gives it five valence electrons, which allows it to donate an electron when substituted into a Group 14 semiconductor crystal lattice, thereby increasing the electron carrier concentration.

Semiconductor Doping and Compound Semiconductors

Antimony is used as a shallow n-type dopant in silicon, particularly for devices requiring a dopant that diffuses slowly at high temperatures, such as deep-trench capacitors and certain power device structures. Its lower diffusion coefficient compared to arsenic makes it preferable when tight dopant profile control is needed at elevated process temperatures. In compound semiconductor systems, antimony forms binary compounds with important optoelectronic properties: indium antimonide (InSb) has one of the highest electron mobilities among known semiconductors, approximately 77,000 cm2/V·s at room temperature, and a direct bandgap in the mid-infrared range that makes it well-suited for infrared photodetectors and thermal imaging arrays. Gallium antimonide (GaSb) and aluminum antimonide (AlSb) serve as substrate and barrier materials in heterojunction devices for near-infrared and mid-infrared laser diodes and photodetectors. These properties are surveyed in materials literature such as EurekAlert coverage of 2D antimony for post-silicon electronics, which describes the charge mobility advantages of antimonene, the two-dimensional allotrope of antimony.

Phase-Change and Memory Applications

Antimony is a component of the phase-change material Ge2Sb2Te5 (GST), the chalcogenide alloy that forms the functional layer in phase-change memory (PCM) and optical data storage. In GST, the amorphous and crystalline phases have distinct electrical resistivities and optical reflectivities, allowing information to be stored and retrieved by switching between them using short thermal pulses. The speed and stability of the phase transition are sensitive to the antimony fraction in the alloy composition, and adjusting the Ge-Sb-Te ratio enables tuning between faster and more stable device characteristics. Research on nanoelectromechanical antifuse interconnects using antimony-based materials illustrates how antimony-based materials are embedded in emerging non-volatile memory architectures.

Electronic and Industrial Uses

Beyond semiconductors and memory, antimony trioxide is widely used as a flame retardant synergist in printed circuit board laminates, cable insulation, and electronic housings, where it acts in combination with halogenated compounds to interrupt combustion chain reactions. Antimony-tin oxide (ATO) films provide transparent electrical conductivity for liquid-crystal display electrodes and antistatic coatings. The strategic importance of antimony has grown as a critical mineral: China currently produces over 50 percent of global supply, and export restrictions imposed in recent years have affected supply chains for electronics and defense systems. The Thermo Fisher antimony materials overview summarizes these supply and industrial dimensions.

Applications

Antimony has applications in a range of fields, including:

• Infrared detector arrays and thermal imaging cameras, through indium antimonide photodetector materials
• Phase-change non-volatile memory and optical storage, as a constituent of Ge2Sb2Te5 alloys
• Semiconductor device fabrication, as an n-type dopant with controlled diffusion characteristics in silicon
• Printed circuit board manufacturing, as a flame-retardant additive in laminate and encapsulant materials
• Transparent conductive electrodes, as antimony-tin oxide films in display and photovoltaic applications