Abstract

The bandwidth of photoconductive submillimeter-wave emitters based on low-temperature-grown (LTG) GaAs is known to decrease at high applied bias, which limits the output power of these devices at frequencies near 1 THz. We performed measurements of an LTG GaAs photoconductor embedded in a coplanar waveguide with both static and dynamic illumination to investigate the bandwidth decrease and an increase in dc photocurrent that occurs at the same bias voltages. We attribute both phenomena to a reduction of the electron capture cross section of donor states due to electron heating and Coulomb-barrier lowering. We discuss why the phenomena can not be explained by injection-limited currents or impact ionization.

© 1999 Optical Society of America