Efficient CW terahertz generation with n-i-pn-i-p photomixers

We report on a concept for highly efficient generation of terahertz (THz) radiation and its verification by experimental studies. The THz generation is based on photomixing in a periodic stack of specially designed pin- photodiodes. This design allows to suppress the slow hole transport, to optimize high-speed ballistic electron transport in the photodiodes and, at the same time, to avoid the degradation of the high-frequency performance due to the usual "RC- roll-off.