Terahertz-emitting devices based on boron-doped silicon

Terahertz light emission was observed near 8 THz from electrically pumped boron-doped Si mesas. Samples were fabricated by depositing contacts using metal evaporation and a standard lift-off technique, followed by multi-step reactive ion etching. At a sample temperature of 4.4 K, we observed total emitted time-resolved powers of up to 31 μW, integrated over three closely spaced spectral lines. The spectral positions of these lines show excellent agreement with published data for transitions between hydrogenic states of the boron acceptor impurity in Si. Our findings suggest that moderate power CMOS-compatible terahertz sources can be fabricated without epitaxially grown quantum wells.