ABSTRACT

"Technology of heterostructure devices for satellite detection systems

at millimeter wavelengths"

            In this work, Single Barrier Varactor Diodes and Coplanar Wave-Guides on a membrane were fabricated and characterized in AC regime.

            The Single Barrier Varactor consists on an heterostructure for a use in harmonic multiplication. This is possible because of the capacitance modulation wich leds to a generation of harmonics. In practice, the heterostructure is a blocking conduction layer of InGaAs/InAlAs/InGaAs or InGaAs/InAlAs/AlAs/InAlAs/InGaAs sample grown by Molecular Beam Epitaxy starting from an InP substrate. Samples exhibit very symetric Capacitance - Voltage characteristics. The best results led to a high capacitance contrast of 5.5 between 0 V and 6 V bias. We also investigted the same heterostructure in a stacked configuration with leakage currents as low as 10 A/cm² at 12 V.

            Coplanar wave-guides deposited on thin Polyimide or Silicon Nitride dielectric films were studied as passive components. The propagation element can be compared to free space with a low relative dielectric index. Such structure were fabricated using micromachining technology of Gallium Arsenile. We demonstrated a constant high velocity of 2.9.10⁸ m/s close to the velocity of the electromagnetic wave in air. It was also demonsrated that there is a predominance of metallic losses with a square root frequency dependence. Then we showed preliminary results of modelling filters at 250 GHz.

            The potential applications of this devices are quazi-optical systems at millimeter and submillimeter wavelengths for detection systems.

KEY-WORDS

Heterostructure, III-V Semiconductor, Varactor Diode, Coplanar waveguides, Transmission lines, Membrane, Filters