Improvement of Fermi-Level Pinning and Contact Resistivity in Ti/Ge Contact Using Carbon Implantation

Effects of carbon implantation (C-imp) on the contact characteristics of Ti/Ge contact were investigated. The C-imp into Ti/Ge system was developed to reduce severe Fermi-level pinning (FLP) and to improve the thermal stability of Ti/Ge contact. The current density (J)-voltage (V) characteristics showed that the rectifying behavior of Ti/Ge contact into an Ohmic-like behavior with C-imp. The lowering of Schottky barrier height (SBH) indicated that the C-imp could mitigate FLP. In addition, it allows a lower specific contact resistivity (ρc) at the rapid thermal annealing (RTA) temperatures in a range of 450–600 °C. A secondary ion mass spectrometry (SIMS) showed that C-imp facilitates the dopant segregation at the interface. In addition, transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) mapping showed that after RTA at 600 °C, C-imp enhances the diffusion of Ge atoms into Ti layer at the interface of Ti/Ge. Thus, carbon implantation into Ge substrate can effectively reduce FLP and improve contact characteristics.

Влияние условий осаждения из паров металлоорганических соединений на получение эпитаксиальных слоев n-CdTe с использованием изопропилиодида

The dependence of iodine incorporation in CdTe layers on the deposition conditions during metalorganic vapor phase epitaxy is investigated. The growth of the layers was carried out from dimethylcadmium and diethyltellurium in the hydrogen flow in a vertical reactor with a hot wall condition at a total pressure of 20 kPa. The total iodine concentration was determined by secondary ion mass spectrometry, the electrically active concentration was determined from the Hall effect measurement. The iodine incorporation depends on the crystallographic orientation of the substrate (were studied (100), (310), (111)A, (111)B, (211)A and (211)B), the concentration of the doping precursor (flux range 5·10–8–3·10–6 mol/min), the mole ratio of organometallic compounds (DMCd/DETe=0.25–4), growth temperature (335–390°C) and the walls of the reactor above the pedestal (hot wall zone 290–320°C). The total iodine concentration reached 5·1018 cm–3 and the activation efficiency was ~4 %. After thermal annealing in cadmium vapor at 500°C the activation efficiency was ~100 %.

Effects of NH3 Plasma and Mg Doping on InGaZnO pH Sensing Membrane

In this study, the effects of magnesium (Mg) doping and Ammonia (NH3) plasma on the pH sensing capabilities of InGaZnO membranes were investigated. Undoped InGaZnO and Mg-doped pH sensing membranes with NH3 plasma were examined with multiple material analyses including X-ray diffraction, X-ray photoelectron spectroscopy, secondary ion mass spectroscopy and transmission electron microscope, and pH sensing behaviors of the membrane in electrolyte-insulator-semiconductors. Results indicate that Mg doping and NH3 plasma treatment could superpositionally enhance crystallization in fine nanostructures, and strengthen chemical bindings. Results indicate these material improvements increased pH sensing capability significantly. Plasma-treated Mg-doped InGaZnO pH sensing membranes show promise for future pH sensing biosensors.