We present an new unbiased antennaless CW THz photomixer made of buried metal/semiconductor/metal (MSM) elecrodes with dis-similar Schottky barriers. The two dis-similar metals in each MSM are in intimate contact, and yet the maximum electric field appearing in the semiconducting material, unlike that in the planar structures, is far below its breakdown threshold. This relaxes the breakdown constraint that is normally confronted in the design of similar THz emitters with planar MSMs. Besides, use of the buried MSMs has increased the volume in which the carriers’ photogeneration occurs, enhancing the resultant CW THz radiation by more than three order of magnitude as compared with a similar emitters but planar MSM electrodes.
