GaSbBi alloys and heterostructures: fabrication and properties

International audienceDilute bismuth (Bi) III-V alloys have recently attracted great attention, due to their properties of band-gap reduction and spin-orbit splitting. The incorporation of Bi into antimonide based III-V semiconductors is very attractive for the development of new optoelectronic devices working in the mid-infrared range (2-5 µm). However, due to its large size, Bi does not readily incorporate into III-V alloys and the epitaxy of III-V dilute bismides is thus very challenging. This book chapter presents the most recent developments in the epitaxy and characterization of GaSbBi alloys and heterostructures

The effect of soil pH and natural fertilizers on the productivity of different mixtures and nitrogen accumulation in plant biomass

Research aimed at comparing the productivity and nitrogen (N) accumulation in plant biomass of different mixtures and permanent meadow grown in soils with different pH was performed. Most of the N was accumulated in permanent meadow grass biomass. Barley/lupine and barley/pea mixtures accumulated considerably less N. In most cases, soil pH had no significant effect on N accumulation. In fact, N accumulation strongly depended on plant productivity. In 2008, there was a more significant decrease in the productivity of barley/lupine mixture, compared to that of 2007. Permanent meadow was a more stable agroecosystem compared with annual mixtures; therefore different agroclimatic conditions had little effect on yield formation (somewhat bigger in 2008, but insignificantly), whereas increase in grass productivity was obtained. Average data for 2007 and 2008 showed that barley/pea mixture was the most productiveVytauto Didžiojo universitetasŽemės ūkio akademij

The effect of soil pH and natural fertilizers on the productivity of different mixtures and nitrogen accumulation in plant biomass

Research aimed at comparing the productivity and nitrogen (N) accumulation in plant biomass of different mixtures and permanent meadow grown in soils with different pH was performed. Most of the N was accumulated in permanent meadow grass biomass. Barley/lupine and barley/pea mixtures accumulated considerably less N. In most cases, soil pH had no significant effect on N accumulation. In fact, N accumulation strongly depended on plant productivity. In 2008, there was a more significant decrease in the productivity of barley/lupine mixture, compared to that of 2007. Permanent meadow was a more stable agroecosystem compared with annual mixtures; therefore different agroclimatic conditions had little effect on yield formation (somewhat bigger in 2008, but insignificantly), whereas increase in grass productivity was obtained. Average data for 2007 and 2008 showed that barley/pea mixture was the most productiveVytauto Didžiojo universitetasŽemės ūkio akademij

Study of p-Fe₃O₄/n-(GaAs,Si) Heterostructures: Fabrication and Physical Properties

We report preparation and investigation of p -n heterostructures based on Fe₃O₄ thin films grown on semiconductor Si and GaAs substrates. Fe₃O₄ films with thickness ranging from 60 to 300 nm were grown at 350÷450°C using dc magnetron sputtering technique. The measurement of X-ray diffraction and reflection high energy electron diffraction revealed polycrystalline microstructure of thin Fe₃O₄ films deposited on both Si and GaAs substrate. Investigation of surface composition by X-ray photoelectron spectroscopy showed that Fe 2p peak consists of three main peaks, namely, metallic iron Fe(0), Fe(II), and Fe(III). Transport measurements of Fe₃O₄/n-(Si, GaAs) heterostructures demonstrated nonlinear current-voltage (I -V) dependences in the temperature range from 300 K to 78 K

Lietuvos mokslas ir pramonė

Vytauto Didžiojo universitetasŽemės ūkio akademij

Synthesis and Electrical Properties of La-Pr-Mn-O Thin Films and Heterostructures

In this paper we report the results of synthesis and study of both ceramic samples and thin films of electronically doped La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$ and related heterostructures composed of La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$ and p-type La$\text{}_{0.67}$Ca$\text{}_{0.33}$MnO$\text{}_{3}$. The ceramic La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$ samples were prepared by a conventional solid state reaction technique. Single phase La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$ thin films and La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$/La$\text{}_{0.67}$ Ca$\text{}_{0.33}$MnO$\text{}_{3}$ heterostructures were grown on lattice-matched perovskite NdGaO$\text{}_{3}$ substrates by pulsed laser deposition. Electron doping was indicated both for ceramic La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$ samples and thin films from thermopower data. Both ceramic samples and thin films of La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$ demonstrated resistivity of about 10 mΩ cm at 300 K and semiconductor-like resistance vs. temperature behavior with cooling down to 78 K. Meanwhile, the resistance of the La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$/La$\text{}_{0.67}$Ca$\text{}_{0.33}$MnO$\text{}_{3}$ interface showed an anomalous peak at 185 K. A series of post-deposition annealing experiments demonstrated a crucial role of annealing temperature and ambience on both electrical and magnetic properties of La$\text{}_{0.7}$Pr$\text{}_{0.3}$MnO$\text{}_{3}$ material and the heterostructures

Growth and Investigation of p−La2//3Ca1//3MnO3p-La_{2//3}Ca_{1//3}MnO_3/n-Si Heterostructures

We report the fabrication and investigation of p-n diode structures based on thin hole-doped $La_{2//3}Ca_{1//3}MnO_3$ films grown on n-type silicon substrates. $La_{2//3}Ca_{1//3}MnO_3$ films with typical thickness of about 400 nm were prepared using pulsed laser deposition. Reflection high-energy electron diffraction measurements revealed polycrystalline quality of $La_{2//3}Ca_{1//3}MnO_3$ thin films on Si substrates. The surface roughness of $La_{2//3}Ca_{1//3}MnO_3$ films investigated by atomic force microscopy was found to be in the range of 25÷30 nm. Studies of electrical properties showed that $La_{2//3}Ca_{1//3}MnO_3$/Si heterostructures exhibit nonlinear asymmetric I-V characteristics both at room temperature and at 78 K. Furthemore, it was shown that these I-V dependences are sensitive to magnetic field, especially at lower voltages

Electroresistance of Electrically Nonhomogeneous La 0.67

Current and electrical field-induced electroresistive effects were investigated for La$\text{}_{0.67}$Ca$\text{}_{0.33}$MnO$\text{}_{3}$/MgO thin films demonstrating nanosized electrical inhomogeneities. Two different models based on enhanced conductivity of intergrain boundaries by injecting spin-polarized carriers from ferromagnetic grains and electrical field-enhanced hopping of carriers in high resistance intergrain media were carried out to explain nonlinear electrical properties of the films