Alexander V. Merkulov

Secondary ion mass spectroscopy investigations of magnesium and carbon doped gallium nitride films grown by molecular beam epitaxy

The incorporation of magnesium and carbon in GaN grown by molecular beam epitaxy (MBE) has been investigated by secondary ion mass spectroscopy (SIMS) and other techniques. We have grown Mg:GaN in a wide range of chemical concentrations -. Low temperature photoluminescence of Mg:GaN is dominated by the donor-acceptor transitions associated with Mg at eV. Carrier concentration for Mg:GaN in the range - with mobilities were measured by the Hall effect technique. In the C:GaN layers, it was found that carbon can be uniformly incorporated into the layer at a concentration . However, at this high concentration there is a tendency for carbon to diffuse into the undoped GaN buffer layer.

Improvement of the photoluminescence from gallium nitride layers grown by MBE with an additional incident indium flux

The effect of using an indium flux during the MBE growth of GaN layers was investigated. The properties of these layers were studied using electron probe microanalysis, secondary ion mass spectroscopy, photoluminescence and cathodoluminescence. The optical properties of the GaN layers are shown to improve as compared with undoped GaN layers grown under nominally the same conditions but without an additional indium flux.

Computer simulation of ion sputtering of polyatomic multilayered targets

Abstract The novel binary collision approximation Monte Carlo (BCA-MC) computer codes TRIRS and DYTRIRS for simulating ion sputtering of polyatomic nonuniform amorphous targets are presented. TRIRS simulates the collision cascade in a target and related secondary processes, including sputtering, damage generation etc., being more realistic than similar MC-BCA codes in modeling low-energy interatomic collisions. These improvements ensure better simulation of low-energy atomic collision processes in nonuniform targets, like sputtering, and ultra-low energy ion implantation. DYTRIRS is the extension of TRIRS which simulates the dynamics of the ballistic stage of ion-induced modification and sputtering for a target under high-fluence ion irradiation. The efficiency of DYTRIRS is verified by comparing the simulation of sputtering and secondary-ion mass-spectrometry in-depth compositional profiling of molecular-beam epitaxy grown two-dimensional (Al,Ga)AsGaAs (001) heterostructures, including structures with silicon and aluminum marker layers.

Secondary-ion mass spectroscopy (SIMS) investigations of Be and Si incorporation in GaN grown by molecular beam epitaxy (MBE)

We have studied the incorporation of Be and Si in GaN grown using molecular beam epitaxy (MBE). From secondary-ion mass spectroscopy (SIMS) measurements, Be was found to have an enhanced diffusion rate at high concentration similar to the behaviour observed previously in GaAs. On the other hand, Si behaves as a conventional n-type dopant with no evidence from SIMS for either segregation or diffusion out of the layer. For Be-incorporated material we report new lines in the PL spectrum for both wurtzite and zinc blende polytypes, and we suggest that Be may be a suitable dopant for the zinc blende material.

Effect of ion sputtering on the statistical properties of a surface

The modification of a gallium arsenide surface during irradiation by heavy cesium ions Cs+ is investigated by measuring the surface height distribution with an atomic force microscope. Both increases and decreases in the rms height σ, an integral parameter of the surface, are observed to occur. It is established that for all experimental samples the roughness of the gallium arsenide surface increases in a 1–100 nm lateral range. Analysis of the structure function yields an estimate of the characteristic lateral dimensions of the surface structures arising during ion etching.