Enhanced hot carrier microwave detectors

Hot carrier detector diodes have given an improvement in sensitivity as video detectors at X-Band when a steep thermal gradient was imposed in the region in the semiconductor where the majority carriers are generated by virtue of the RF signal. Temperature gradients of the order of 10,000 degrees/cm were obtained by mounting the semiconductor die on a bismuth telluride cooling couple and pumping the heat through the semiconductor die from the ohmic point contact. The interaction of the AC thermoelectric effect with a DC thermal gradient produces the enhancement which can be understood in terms of non-equilibrium carrier concentrations generated in distances less than the carrier diffusion length. A simple one dimensional model with linear temperature gradients shows enhancements of the order of magnitude observed.