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Mots-Clés / Keywords

Microtechnology; Microhotplate; Semi-conducting gas sensors;

Abstract

This letter reports for the first time the interesting behavior of the interface between indium tin oxide (ITO) as a high resistive electrode and barium strontium titanate tunable paraelectric thin film material. The interface is consisting of barium strontium titanate (BST) thin film dielectric material sandwiched between two ITO high resistive layers, all are integrated above glass substrate. When dc field is applied between the ITO layers, the BST thin film material properties are tuned. It is found that the ITO/BST/ITO heterostructure exhibits a tunable resistor performance. To our knowledge; these results are never reported.

Mots-Clés / Keywords

Agile components; BST; Characterization; Distributed tuning; Indium tin oxide; matching circuits; Material parameters; Metamaterial; Thin films; Tunability; Tunable circuit; Tunable resistor;

Abstract

We report an experimental study of GaAs etching by ICP-RIE based on Cl2:N2 chemistry. The influence of the RF source power, the chlorine dilution, the RF platen power, and the process pressure at several substrate temperatures are investigated. An optimized process is proposed to get routinely GaAs nanowires of 1 ¼m high and about 30 nm in diameter with a full top-down approach combining electron beam lithography and Ni lift-off steps.

Mots-Clés / Keywords

GaAs nanowires; Top-down; Plasma etching; ICP-RIE; Cl2/N2 chemistry;

Abstract

This paper introduces the use of germanium as resistive material in RF MicroElectroMechanical (MEMS) devices. Integrated resistors are indeed highly required into RF MEMS components, in order to prevent any RF signal leakage in the bias lines and also to be compatible with ICs. Germanium material presents strong advantages compared to others. It is widely used in microtechnologies, notably as an important semi-conductor in SiGe transistors as well as sacrificial or structural layers and also mask layer in various processes (Si micromachining especially). But it also presents a very high resistivity value. This property is particularly interesting in the elaboration of integrated resistors for RF components, as it assures miniaturized resistors in total agreement with electromagnetic requirements. Its compatibility as resistive material in MEMS has been carried out. Its integration in an entire MEMS process has been fruitfully achieved and led to the successful demonstration and validation of integrated Ge resistors into serial RF MEMS variable capacitors or switches, without any RF perturbations.

Mots-Clés / Keywords

Germanium; RF MEMS; Integrated resistor; Millimeter waves; Process compatibility;

Abstract

The effects of thermal annealing on optically transparent electrodes of ITO (indium tin oxide) contact deposited on p-type Be-doped GaAs have been investigated by means of the transfer length method and secondary ion mass spectroscopy measurements. This study shows that the temperature that minimizes the specific contact resistance of ITO/GaAs (500 °C) greatly differs from the temperature that leads to a maximum conductivity of the ITO layer (600 °C) and from the values reported on ITO/GaAs in the literature. The oxygen diffusion in the semiconductor layer and its interaction with the beryllium dopant is pointed out to explain these differences.

Mots-Clés / Keywords

ICP-RIE; Plasma etching; Cl2/N2 chemistry; GaAs nano-columns; GaAs nanowires;

Abstract

The main goal of this work is to realize a metal oxide gas sensor with stable operating temperature. This article describes our approach and the technological process used to reach a high and stable operating temperature (650-700°C), with low consumption (100mW) and good thermal homogeneity all over the active area.

Mots-Clés / Keywords

Micro-hotplates; Semi-conducting gas sensors; Nanoparticles; Micro-cavity; Tin oxides; Microtechnology; Inter-digitized electrodes;