A new concept for highly efficient THz photomixers based on quasi ballistic transport and thin LT-GaAs recombination layers

We report on a ~ J C W concept for highly eflcient THzphotomirers using the lurge carrier cross section of low temperature grown (LT-)GaAs. It is based on a periodic n-i-pn-i-p heterostructure with thin LT-GaAs layers incorporated bemeen the nand p-layers. The i-layers are optimized with regard to the generation and ballistic transport of photo-generated electrons in the built-in space chargefields with ballisticflight times smaller than a THz cycle. The LTlayers allow eflcient recombination of electrons and holm arriving from opposite directions in neighboringperiods. This concept is veryproniising to overcome the limitations of conventional photomixer concepts and is expected to exhibit improved THz outputpower as well as conversion efjiciency