A high temperature hybrid-circuit structure includes a temperature sensitive device which comprises SiC, AlN and/or Al_xGa_1-xN(x0.69) connected via electrodes to an electrically conductive mounting layer that is physically bonded to an AlN die. The die, temperature sensitive device and mounting layer, which can be a thin film of W, WC or W₂C less than 10 micrometers thick, have temperature coefficients of expansion within 1.06 of each other. The mounting layer can consist entirely of a W, WC or W₂C adhesive layer, or an adhesive layer with an overlay metallization having a thermal coefficient of expansion not greater than about 3.5 times that of the adhesive layer. Applications include temperature sensors, pressure sensors, chemical sensors and high temperature and high power electronic circuits. Without the mounting layer, a thin film piezoelectric layer of SiC, AlN and/or Al_xGa_1-xN(x0.69), less than 10 micrometers thick, can be secured to the die.