micro - scale and nano - scale devices which achieve high frequency signals ug materials having increased electron saturation velocity . these devices have frequencies in the terahertz range with high temperature and radiation hard characteristics . the transit time device includes a substrate , a buffer layer and an epitaxial layer made of a material in the 43 m and 6 mm crystallographic point groups and associated alloys , and at least two contacts on the device . in operation , one contact is forward biased and the other is reversed biased . applications for this devices include transit - time - based oscillators for use in military and civilian radar receivers , logic devices , burglar alarm and proximity alarm systems .