World's first semiconductor maser is silicon-carbide-based and performs continuous microwave amplification at room temperature
https://www.eurekalert.org/news-releases/1138933 "removing silicon atoms from semiconductor's crystal lattice which is then optically excited creates atomic defect spin states... coupled with high-quality-factor resonator becomes microwave device that avoids extreme cooling traditionally required for masers... low-noise signal amplifier, ultra-sensitive magnetometer enabling magnetic field detection down to 20 pT... spin states can also be controlled electrically, for compact, chip-integrated maser diodes for communications, quantum metrology, sensing"