Matrix-seeded growth of nitride semiconductor nanostructures using ion beams

Theoretical multiscale model of nitride semiconductor nanostructure is proposed. The model combines various computational methods such as density functional theory, molecular dynamics and kinetic Monte Carlo. As a first step of implementation of proposed approach ab initio calculations of structural and electronic properties of two different structures InN/Si and AlN/AlGaN/GaN heterostructures were carried out. In particular, the influence of oxygen on InN/Si adhesion energy was studied. AlN, GaN, AlxGa1-xN (x=0.33) spontaneous and piezoelectric polarizations as well as sheet carrier concentrations at GaN/AlGaN interface were calculated. Obtained value for sheet carrier concentration at GaN/AlGaN interface is close to experimental data.

Download Full-text

Axial Observation of X-Ray Spectra from a Beam-Foil Source

International Astronomical Union Colloquium ◽

10.1017/s0252921100108048 ◽

1988 ◽

Vol 102 ◽

pp. 339-342

Author(s):

J.M. Laming ◽

J.D. Silver ◽

R. Barnsley ◽

J. Dunn ◽

K.D. Evans ◽

...

Keyword(s):

Spectral Resolution ◽

Heavy Ion ◽

Ion Beams ◽

Beam Axis ◽

Doppler Broadening ◽

X Ray ◽

Beam Foil

AbstractNew observations of x-ray spectra from foil-excited heavy ion beams are reported. By observing the target in a direction along the beam axis, an improvement in spectral resolution, δλ/λ, by about a factor of two is achieved, due to the reduced Doppler broadening in this geometry.

Download Full-text

Preparation of TEM samples by focused ion beams

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138968 ◽

1995 ◽

Vol 53 ◽

pp. 518-519

Author(s):

John F. Walker ◽

J C Reiner ◽

C Solenthaler

Keyword(s):

Integrated Circuit ◽

Polycrystalline Silicon ◽

Field Effect Transistor ◽

High Spatial Resolution ◽

Ion Beam ◽

Ion Beams ◽

Focused Ion Beams ◽

Precise Location ◽

Effect Transistor ◽

Circuit Technology

The high spatial resolution available from TEM can be used with great advantage in the field of microelectronics to identify problems associated with the continually shrinking geometries of integrated circuit technology. In many cases the location of the problem can be the most problematic element of sample preparation. Focused ion beams (FIB) have previously been used to prepare TEM specimens, but not including using the ion beam imaging capabilities to locate a buried feature of interest. Here we describe how a defect has been located using the ability of a FIB to both mill a section and to search for a defect whose precise location is unknown. The defect is known from electrical leakage measurements to be a break in the gate oxide of a field effect transistor. The gate is a square of polycrystalline silicon, approximately 1μm×1μm, on a silicon dioxide barrier which is about 17nm thick. The break in the oxide can occur anywhere within that square and is expected to be less than 100nm in diameter.

Download Full-text

Atomic force microscopy (AFM) of the topography of silicon surfaces exposed to ion beams

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130298 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1132-1133

Author(s):

Mark Denker ◽

Jennifer Wall ◽

Mark Ray ◽

Richard Linton

Keyword(s):

Secondary Ion Mass Spectrometry ◽

Incidence Angle ◽

Ion Beam ◽

Depth Profiling ◽

Depth Resolution ◽

Ion Beams ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Trace Impurities ◽

Energy Dose

Reactive ion beams such as O2+ and Cs+ are used in Secondary Ion Mass Spectrometry (SIMS) to analyze solids for trace impurities. Primary beam properties such as energy, dose, and incidence angle can be systematically varied to optimize depth resolution versus sensitivity tradeoffs for a given SIMS depth profiling application. However, it is generally observed that the sputtering process causes surface roughening, typically represented by nanometer-sized features such as cones, pits, pyramids, and ripples. A roughened surface will degrade the depth resolution of the SIMS data. The purpose of this study is to examine the relationship of the roughness of the surface to the primary ion beam energy, dose, and incidence angle. AFM offers the ability to quantitatively probe this surface roughness. For the initial investigations, the sample chosen was <100> silicon, and the ion beam was O2+.Work to date by other researchers typically employed Scanning Tunneling Microscopy (STM) to probe the surface topography.

Download Full-text