Consisting of Ge and Te compounds, mainly used in thin film deposition processes such as magnetron sputtering (PVD) and electron beam deposition.

Its physical properties such as unique phase transition characteristics, thermoelectric performance, and ferroelectricity are important in the fields of phase transition memory, thermoelectric conversion, infrared exploration, and lithium-ion batteries.

1. Properties

1) Phase transition properties

・GeTe can rapidly convert between crystalline (α-GeTe) and amorphous (β-GeTe), and its phase transition temperature is about 725°C, making it suitable for phase change random access memory (PCRAM) applications.

・The change in resistivity during the phase transition process is remarkable(~3 to 4 digits), this material can be used for high density memory devices.

2) Excellent thermoelectric performance

・It has relatively high thermoelectric properties (ZT value), which is prominent among high-temperature thermoelectric materials 　　(ZT can reach 2.0 or more).

・Carrier mobility can be optimized by adding In, Bi, Cu, etc. to improve thermoelectric conversion efficiency.

3) Narrow band gap and high carrier mobility

・The band gap is about 0.6 eV, which is suitable for infrared light detection applications.

・High carrier mobility (~ 100 cm²/V-s) suitable for high-speed electronic devices

4) Ferroelectricity and spintronics applications

・Ferroelectricity and can be used for Ferroelectric random access (FeRAM).

・It shows spin-orbit coupling effect in spintronics and can be used for novel memory and logic devices.

5) High Purity and adjustable ingredients

・The purity of industrial-grade GeTe targets is ≥99.99%, and for high-end applications (e.g., semiconductors), it can reach 99.999% or higher.

・Electrical and thermal properties can be optimized by adding Pb, Bi, In, etc.

2. Main applications

1) Phase change random access memory (PCRAM)

・PCRAM realizes data storage by utilizing the difference between crystalline and amorphous resistance, and has the advantages of high speed, low power consumption, and high durability.

2) Thermoelectric conversion devices

・Thermoelectric conversion devices are used for waste heat power generation and solid-state cooling, and have potential     applications in fields such as aerospace and automotive waste heat recovery.

3) Infrared detectors

・Narrow band gap is suitable for infrared detection and can be used for night vision, thermal imaging, etc.

4) Lithium/sodium/potassium ion battery anode materials

・Monolayer GeTe has high theoretical specific capacity (Li: 535.4 mAh/g, Na: 669.2 mAh/g, K: 1070.72 mAh/g) and is suitable for high-power batteries.

5) Spintronics and quantum computation

・Coupled spin-orbit devices and topological quantum computation materials can be used for research.

 3. Latest development trends

・n-type doping optimization: Improvement of thermoelectric performance by adding Bi, In, etc.

・Flexible GeTe films: for wearable thermoelectric devices.

・Quantum dot GeTe: for high efficiency photodetectors.