abstract the structural and electrostatic properties of the single-walled two representative (8, 0) zigzag and (4, 4) armchair models of pristine and gaas-doped on boron phosphide nanotubes (bpnts) was investigated by calculating the nuclear magnetic resonance tensors and with performing the density function theory. the geometrical structures of all representative pristine and gaas-doped models...

Effects of d-doping on barriers effective heights and series resistance of highly doped n-type GaAs/AIAs/GaAs/AlAs/GaAs heterostructures, grown by molecular beam epitaxy (MBE) at 400?°C, have been studied. As it was expected, inclusion of an n+ d-doped layer at each hetero-interface has reduced the barriers heights and series resistance of the structure significantly, while p+ d-doped layers ha...

We identified the charge carrier compensation mechanism in Te-doped GaAs with atomically resolved scanning tunneling microscopy. Three types of defects were found: tellurium donors (TeAs), Ga vacancies (VGa), and Ga vacancy–donor complexes (VGa– TeAs). We show quantitatively that the compensation in Te-doped bulk GaAs is exclusively caused by vacancy– donor complexes in contrast to Si-doped GaA...

The authors present a method for obtaining graphitized carbon on GaAs 100 surfaces. Carbon-doped GaAs is grown by molecular beam epitaxy before controlled thermal etching within the growth chamber. An AlAs layer beneath the carbon-doped GaAs acts as a thermal etch stop. As the GaAs is etched away, the carbon dopant atoms remain on the surface due to their low vapor pressure. The total number of...

OF DOCTORAL DISSERTATION HELSINKI UNIVERSITY OF TECHNLOGY P.O. BOX 1000, FI-02015 TKK http://www.tkk.fi Author Heikki Holmberg Name of the dissertation Spin-dependent transport in Mn Doped GaAs and GaN diodes Manuscript submitted 16.11.2007 Manuscript revised 4.2.2008 Date of the defence 14.3.2008 Monograph Article dissertation (summary + original articles) Faculty Faculty of Electronics, Commu...

Electrical and physical properties of a metal-oxide-semiconductor [MOS] structure using atomic layer-deposited high-k dielectrics (TiO2/Al2O3) and epitaxial GaAs [epi-GaAs] grown on Ge(100) substrates have been investigated. The epi-GaAs, either undoped or Zn-doped, was grown using metal-organic chemical vapor deposition method at 620°C to 650°C. The diffusion of Ge atoms into epi-GaAs resulted...

High resolution x-ray diffraction using synchrotron radiation was used to characterize GaAs grown by MBE at low temperatures (LT-GaAs). LT-GaAs grown at 225~ is nonstoichiometric and exhibits a 0.15% lattice expansion along the growth direction. Annealing LT-GaAs results in arsenic clusters with a well-defined orientation relationship with the GaAs matrix and a relaxation of the LT-GaAs lattice...

We report on THz emission from plasma oscillations in semiconductors excited by femtosecond optical pulses. Time-resolved correlation measurements are performed on p-i-n and n-doped GaAs structures. In p-i-n structures coherent oscillations of the hot photogenerated carrier plasma emit THz radiation. A fundamentally new emission process is proposed in n-doped GaAs structures. Here, the screenin...

In this paper we propose a microwave detector based on a AlGaAs/ InGaAs/GaAs structure. Its operation relies on non-uniform carrier heating of the two-dimensional electron gas in the microwave electric fields which is a result of the asymmetric shape of the device fabricated on the base of pseudomorphic modulation doped AlGaAs/InGaAs/GaAs structure. The voltage sensitivity of the device at nitr...

Mn-doped GaAs is studied with a real-space Hamiltonian on an fcc lattice that reproduces the valence bands of undoped GaAs. Large-scale Monte Carlo (MC) simulations on a Cray XT3, using up to a thousand nodes, were needed. Spin-orbit interaction and the random distribution of the Mn ions are considered. The hopping amplitudes are functions of the GaAs Luttinger parameters. At the realistic coup...