Experimental determination of phosphorous cross-contamination during antimony implantation is presented. As a suitable structure for this experiment, a buried layer was employed which is created by implanting antimony followed by a long diffusion process. The implanted samples were analysed by SIMS and spreading resistance (SRP) methods. SRP method has been improved by applying a correction for the carrier spilling effect. A conversion chart for p–n junction depth dependence on phosphorus doping has been calculated by program SUPREM-IV. Comparison of SRP and SIMS methods has shown that SRP method can be used for monitoring the phosphorus cross-contamination and can be easily implemented as an in-line monitor and present an alternative to expensive and time consuming SIMS analysis.

As CMOS is approaching the 22nm node, the importance of high-mobility materials such as Ge and GaAs is rapidly increasing. For the timely development of these new technologies accurate dopant and carrier-profiling solutions for source-drain extensions with these materials are required. Identical n-type-doped (Si, Se) layers on same and opposite type medium-doped layers on S.I. GaAs substrates will be investigated, with layer thicknesses ranging from 200 down to 50nm and doping concentration levels up to 1e20at/cm3. In this work, secondary ion mass spectrometry will be used for dopant profiling. For GaAs carrier profiling, conventional spreading resistance probe, as commonly used in Si-CMOS, fails. Hence, reliable alternatives need to be found for characterizing these high–low structures. Techniques to be discussed range from the more conventional approaches such as Hall or electrochemical capacitance–voltage (performed by different laboratories), over micro-Raman spectroscopy and photo-luminescence along a beveled surface, up to more advanced approaches using scanning spreading resistance microscopy.

Boron outdiffusion from the base into the emitter and collector caused by annealing in SiGe heterobipolar transistors (HBTs) has a serious influence on the transit frequency. One solution of the problem of boron outdiffusion is the creation of intrinsic spacers between the base, emitter and collector layers to prevent diffusion of boron across the heterointerface. For optimisation of SiGe HBT properties, several simulators are used. This paper presents a quantitative analysis of a SiGe HBT by process simulators SUPREM IV.GS and ISE TCAD-DIOS. Models for simulation of a boron-doped SiGe base of HBT are discussed and compared.

An efficient and mild intramolecular exo-hydrofunctionalization of allenyl carbamates, alcohols and indoles to give pyrrolidines, piperidines, tetrahydrofurans, tetrahydropyrans, and fused indoles under Au(I)-Ag(I) catalytic conditions is reported. Use of a sterically hindered o-biphenyl ligand is crucial for the success of the reaction. The methodology is effective for both protected γ,δ-allenyl amines and alcohols and tolerates substituents at internal and terminal allenyl carbon atoms. An interesting effect of the counteranion was observed: the use of AgOTf in the Au-catalyzed hydroalkoxylation of 2,2-diphenyl-γ-allenyl alcohol led to a 1:1 ratio of 5-exo/6-endo hydroalkoxylation products while almost only the 5-exo cyclization product was formed using AgOTs.

This Rh(I)-catalyzed asymmetric cyclization-hydroboration of 1,6-enynes provides an expedient route to functionalized carbocycles and heterocycles. The sequence can be terminated either via Pd-catalyzed arylation or by oxidation to access the corresponding ketone. 1,7-Enynes and 1,6-enynes that possess either a terminal alkyne or a substituted alkene bond did not undergo the desired cyclization. This is a complementary variation of a Rh-catalyzed cyclization-arylation of enynes with arylboronic acids reported by T. Miura et al. J. Am. Chem. Soc. 2005, 127, 1094-1095. The use of catecholborane as the borylating agent in the present method allows for subsequent transformation of the boronic ester intermediate.

Phosphorus diffusion into strained SiGe layers was studied by different methods. Doping profiles and carrier concentration profiles N(x), depth of pn junction, Ge content in SiGe and thickness of epitaxial layer were measured and simulated. Several experimental methods such as secondary ion mass spectroscopy, spreading resistance method, Raman spectroscopy—and process simulator ISE TCAD have been used. The results obtained by different methods and at different places of work have been compared and analysed.

This article deals with the design, construction and a control program of an automatic measuring system (AMS). The AMS allows to obtain the carrier concentration profile n(x) and mobility profile µ(x) from the sheet resistance and sheet Hall mobility by van der Pauw measurements, while gradually removing layers of the semiconductor by anodization/etch procedures. AMS can also be used for sheet resistance measurements by the four-point-probe method and for calculating the specific resistance. Further, the software of the AMS contains graphical subroutines for conversion of resistivity to concentration and mobility. The experimental n(x) profile has been compared with that calculated by program SUPREM. K e y w o r d s: Hall system, van der Pauw, Si, four point probe, SUPREM

Experimental determination of phosphorus cross-contamination during antimony implantation is presented. As a suitable structure for this experiment, a buried layer was employed which is created by implanting antimony followed by a long diffusion process. The samples implanted in different implanters were analysed by secondary ion mass spectrometry (SIMS), four-point probe and spreading resistance methods. The obtained results were compared with those calculated by program SUPREM-IV. Methods that can and cannot be used to determine phosphorus contamination during antimony implantation and to estimate the fluence of phosphorus being co-implanted with antimony are described in detail.

The diffusion process and its influence on the broadening of the base bounded from both sides by undoped spacer layers of an npn SiGe HBT have been investigated by process simulator JSE TCAD. Boron diffusion into strained SiGe layers was studied for different times of annealing, Ge content in SiGe and widths of undoped spacer layers.

The PCIV (Point Contact Current-Voltage) methodfor determination afthe doping concentration profiles of Si structures on a bevelled surface is presented. The equipment initially intended for the spreading resistance (SR) method was modified considerably to allow measurements by pew technique. In this article the designed and constructed measuring device is described A calibration technique for measurements on Si and an analysis of the range of carrier concentration that can be measured by PClV technique on Si samples are presented. Also results of measurement on epitaxial and implanted Si samples are given. The results obtained by PClV method are compared with the results obtained by the spreading resistance technique (SSM.150 equipment).

This paper reports a method for the determination of doping concentration profile in single and multi δ-doped GaAs layers on bevelled samples. The method is based on the recording and evaluation of micro-photoluminescence spectra along the bevelled structure. The values for the doping concentration profiles are in good agreement with those obtained by C–V, SIMS and Raman spectroscopy.

When magnetic tunnel junctions (MTJ) are built into a memory device they will be arranged in a matrix; therefore some of the not addressed elements will be exposed to a significant field during the switching of one element. It has to be avoided that the state of not selected MTJ is changed during this process. Here we present data on the stability of MTJ against small fields which occur during a writing process.

Sub-micron sized magnetic tunnel junctions are fabricated by electron beam lithography. Magneto resistance measurements were done at crossed easy- and hard-axis fields and the critical switching curves for 3 different sub-mum junctions are discussed. Single domain like switching according to the Stoner and Wohlfarth model can be achieved, but Neel coupling effects and AAF stray field effects have to be controlled. (C) 2002 Elsevier Science B.V. All rights reserved.

Bevels through Si/SiGe structures were prepared by chemical etching. The surface of the bevels was smooth and bevel angles were in the range 10(-4) rad. From the Raman spectra along the bevels the thickness and composition of SiGe alloys were determined and compared with photocurrent response spectrum of the structures.

Determination of doping concentration profiles of GaAs on a bevelled surface by the probe method is presented. The bevelled structures were prepared by, chemical etching. The results are compared with electrochemical capacitance-voltage technique. Some specific problems are discussed.

This work presents the investigation of MOVPE growth of silicon δ-doped GaAs and AlxGa1−xAs epilayers and different methods used for their characterisation. The influence of the growth temperature, SiH4 flow rate and AlxGa1−xAs composition on δ-doping characteristics is discussed. Properties of the Si δ-doped structures were examined using capacitance–voltage (C–V) measurements, photoreflectance spectroscopy, micro-photoluminescence, micro-Raman and photocurrent spectroscopies.

Electrochemical capacitance-voltage (ECV) techniques and the four-point probe method have been used to determine the carrier profile N(x) and the depth of the p+-n junction of a boron implanted silicon wafer. It was found that the p+-n junction depth can provide reliable information only if certain limitations are considered in detail. The results obtained by ECV were compared with those computed by SUPREM.

Investigation of MOVPE growth of silicon delta -doped GaAs, AlAs and AlxGa1-xAs epilayers and different methods used for their characterisation are presented. The epitaxial structures were grown in an atmospheric pressure horizontal AIX 200 Aixtron reactor. Delta doping was formed by SiH, introduction during the growth interruption. The influence of the growth temperature and AlxGa1-xAs composition on delta-doping characteristics, carrier concentration and mobility is discussed. Properties of the investigated Si delta -doped structures were examined using capacitance -voltage measurements, Van der Pauw-Hall measurements (300K, 77K), photocurrent measurements, photoreflectance spectroscopy and X-ray measurements.

Electric transport through magnetic tunnel junctions (MTJs) has been studied at various temperatures to gain understanding of the transport mechanisms in such devices. Between 15 and 400 K, MTJs with Al2O3 barriers have been tested at low voltage (barrier height: 2.0–2.1 eV, barrier width: 1.5 nm). For the soft-magnetic electrode a sputtered 1 nm Co/6 nm Fe double layer was used. The hard-magnetic electrode is realized with a 1.5 nm Co/1.0 nm Cu/1.0 nm Co system. Antiferromagnetic coupling between the two Co layers leads to a high saturation field. The 1.5 nm Co layer is used as the second electrode of the MTJ. The conductance increases with growing temperature while the tunnel magnetoresistance (TMR) shows a slight decrease. For interpretation of the results, the temperature dependence of direct tunneling, of the hopping conductance via trapped states, and of the interface magnetization have to be taken into consideration. The dominant factor for the TMR is proportional to 1−BT3/2 and follows the temperature dependence of the interface magnetization. The experimental data allow us to separate transport mechanisms and characterize the junction quality. At room temperature the spin-independent hopping conductance of our junctions is calculated to be less than 10% of the total conductance. Concerning the magnetic properties, a ferromagnetic orange-peel coupling corresponding to a field of about 4 Oe (0.3 kA/m) was found at 15 K, which decays exponentially with increasing temperature to less than 0.6 Oe (0.05 kA/m) at 300 K. The coercive field of the soft layer also shows an exponential decay.

A method for determining the carrier concentration profile N(x) and the depth of p(+)-n junction boron implanted silicon using the electrochemical capacitance-voltage method, and EBIC (electron beam induced current) is presented. The above mentioned methods were found to be suitable for characterizing the implantation process. Experimental results have been compared with theoretical ones based on Gauss N-G(x) and Pearson IV N-p(x) distributions and with those obtained by means of EBIC.