Infrared and terahertz emitters based on group IV semiconductors

Infrared and Terahertz emitters have found their applications in fields such as medicine, industry, and scientific research. Methods for generating and detecting infrared and terahertz radiation are constantly evolving. This study explores two general areas of infrared and terahertz technologies. First, the growth, fabrication and electroluminescence spectroscopy of group IV optoelectronic emitters based on GexSn1-x alloys have been investigated. Second, injection current induced terahertz electroluminescence in SiC P-N junction has been investigated.;Optoelectronic devices at the near-IR spectrum can be realized in group IV semiconductors using band engineering and alloying. Germanium-Tin (GeSn) alloys are technologically important for group IV based optoelectronic devices due to the possible transformation of the bandgap from indirect to direct for sufficient Sn content. At room temperature, GeSn alloys offer a wide range of possible bandgap energies ranging from 0.66 eV to 0 eV. This work reports on the electrical characterization and electroluminescence (EL) measurements of P-N heterojunction diodes fabricated from layers of boron doped p-type GeSn grown by molecular beam epitaxy (MBE) on n-type Ge-substrates. Electrical characterization of various GeSn p-n diodes with varying Sn content have been studied to extract various diode parameters with varying Sn content. Infrared spectral emission at 2.15um (0.57eV) have been observed from the electrically pulsed diode at room temperature using FT-IR spectroscopy, which increased in intensity with current. The total integrated emitted power of ~ 50 microwatt have been reported at an applied peak current of 100 mA at a temperature of 100 K. To our knowledge, this is the first time that EL has been observed and reported from p-GeSn/n-Ge diodes with Sn content above 6 atomic percent.;Over the past decade, a lot of research has been focused on Terahertz (THz) emitters and lasers. Shallow impurity intra-center transition in bulk silicon have become attractive as emitters because they are much simpler then quantum cascade lasers. In silicon, the operating temperature for THz emitters is limited by the small activation energy of impurities. SiC devices can be used at higher temperature and can give a high power operation in the THz range. This work reports on THz emission from 4H-SiC p-n junction diodes with current injection induced intracenter optical transitions of dopants in SiC using FT-IR spectroscopy. Injection induced THz EL in SiC P-N junction could allow one to get the emission at significantly reduced voltages on an emitting device ("THz LED"). The operating device drive current for the THz emission is of the order of 10 times less than that of the previously reported impact ionization emitter based on unipolar SiC structures. The temperature and current dependence of THz intensity from SiC p-n junction have also been investigated.