Terahertz emission from heavily-doped p-type silicon hole arrays
We investigated the terahertz (THz) emission properties in heavily-doped p-type silicon (Si) hole arrays. Deep etching of Si decreases the free carrier density thereby enhancing the THz emission due to reduced free carrier absorption. We fabricated the Si hole arrays using a two-step metal-assisted chemical etching technique and employed THz time-domain spectroscopy in reflection and transmission geometries to measure the THz spectra. Results showed enhancement on the THz emission of the heavily-doped Si hole arrays for longer etch times. However, the THz emission significantly dropped after an etch time of 6 hours and 30 minutes.