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A transmission electron microscope is employed for the microanalysis of the lattice site and the characteristic, intra-atomic photoluminescence feature of the substitutional Mn in very high quality GaMnN layers at 1.41 eV. The results clearly show that the most of the Mn atoms in the samples are located on the substitutional Ga site, as the shape and intensity of the PL line are highly sensitive to the structural properties of the grown layers.

The effect of Si-doping on the morphology, structure, and transport properties of nanowires was investigated. The nanowires were deposited by selective-area metal organic vapor phase epitaxy in an N2 ambient. It is observed that doping systematically affects the nanowire morphology but not the structure of the nanowires. However, the transport properties of the wires are greatly affected. Room-temperature four-terminal measurements show that with an increasing dopant supply the conductivity monotonously increases. For the highest doping level the conductivity is higher by a factor of 25 compared to only intrinsically doped reference nanowires. By means of back-gate field-effect transistor measurements it was confirmed that the doping results in an increased carrier concentration. Temperature dependent resistance measurements reveal, for lower doping concentrations, a thermally activated semiconductor-type increase of the conductivity. In contrast, the nanowires with the highest doping concentration show a metal-type decrease of the resistivity with decreasing temperature. [ABSTRACT FROM AUTHOR]

We report the results of direct measurements and a theoretical investigation of the in-plane effective mass in the two-dimensional electron gas of nominally undoped AlGaN/GaN heterostructures with a different degree of quantum confinement. It is shown that in most cases the conduction band nonparabolicity effect is overestimated and the electron wave-function penetration into the barrier layer should be taken into account. The contribution of the wave-function hybridization is determined to play the dominant role. The band edge effective mass value is deduced to be (0.2±0.01)m0. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the structural properties of AlGaN/GaN heterostructures grown by metal organic chemical vapor deposition on sapphire substrates with different thicknesses using high-resolution x-ray diffraction and Raman scattering methods. We discuss the microscopic nature of spatial-inhomogeneous deformations and dislocation density in the structures. Microdeformations within mosaic blocks and the sizes of regions of coherent diffraction are determined. We reveal a gradient depth distribution of deformations in the mosaic structure of nitride layers, as well as at the interface regions of the sapphire substrate on the microscale level using confocal micro-Raman spectroscopy. We determine that an increase in substrate thickness leads to a reduction in dislocation density in the layers and an increase in the elastic deformations. The features of the block structure of nitrides layers are shown to have a significant influence on their elastic properties. [ABSTRACT FROM AUTHOR]

The effect of a small dose of gamma irradiation on transport characteristics of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures was investigated. It is shown that the carrier concentration remains practically unchanged after an irradiation dose of 106 rad, while the 2DEG mobility exhibits a considerable increase. The results are explained within a model that takes into account the relaxation of elastic strains and structural-impurity ordering occurring in the barrier layer under irradiation. [ABSTRACT FROM AUTHOR]

The wurzite type gallium nitride doped by gadolinium ([Ga.sub.1-x][Gd.sub.x]N) is prepared by Gd ion implantation of the parent GaN thin films deposited on sapphire substrates. The material has displayed a weak ferromagnetism (FM), which is present up to 700 K.

Deals with a study which determined the optical and electrical properties of modulation doped In[subx]Ga[sub1-x]/InP single quantum wells. Experimental details; Experimental results; Analysis and discussion.

Investigates the effect of electron cyclotron resonance plasma cleaning on the contact resistance between a superconducting Nb layer and a two-dimensional electron gas in a strained In[sub x]Ga[sub 1-x]As/InP heterostructure. Semiconductor surface created by cleaning by a He/H plasma results.

Provides information on an experimental report on the observation of quantized conductance in split-gate In0.53Ga0.43As/Ga0.77In0.23As/InP point contacts. Methodology used to conduct the experiment; Results of the experiment.