摘要:

A deep level transient spectroscopy (DLTS) study of 450 °C annealed Czochralski silicon is presented. Particular attention is given to the relative concentrations of the two thermal donor energy levelsEc−0.15 eV andEc−0.07 eV. Relative concentrations of theEc−0.15 eV andEc−0.07 eV energy levels indicate that there are fewer of the more shallow level. Also there is anomalous motion of the energy levels with anneal time indicating the gradual accretion of the thermal donor complexes. The suggested correlation with infrared absorption (IR) studies is that the nine double‐donor defects found by IR form sequentially in the material and the DLTS energy level obtained merely reflects the most abundant of the nine distinct complexes. This indicates that the nine thermal donors are formed by the addition of some constituent to an earlier complex. As the thermal donor complex accretes the associated energy levels change, moving to shallower energies as anneal time increases. These findings tend to contradict the simple thermal donor models.

ISSN:0003-6951    

DOI:10.1063/1.104977

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Ultrahigh‐vacuum chemical vapor deposition has been exploited to grow single‐heterojunctionn‐type modulation‐doped Si/SiGe structures. Phosphorus dopant is imbedded in the SiGe layer at two distinct positions: one at the surface to prevent depletion by surface states, and the other separated from the Si heterointerface by an intrinsic SiGe spacer, to supply electrons to the two‐dimensional electron gas. With a 4‐nm‐thick spacer layer, peak mobilities of 1800 cm2/V s, 9000 cm2/V s, and 19 000 cm2/V s were measured at room temperature, 77 and 1.4 K, respectively. These are the highest values reported for this material system.

ISSN:0003-6951    

DOI:10.1063/1.104978

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We predict, on the basis ofabinitiototal energy calculations, that epitaxial growth of I‐VII compounds on III‐V substrates can be accomplished. We suggest specific combinations of I‐VII materials and III‐V substrates that minimize lattice mismatch and structural energy cost and show that the interface dipole can be minimal. This makes zinc‐blende I‐VII materials potential candidates for passivating layers, solid‐state laser applications, III‐V window material, and hole traps.

ISSN:0003-6951    

DOI:10.1063/1.104979

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

It has recently been reported that there is anomalous enhanced diffusion of B through the gate oxide in metal‐oxide‐semiconductor (MOS) structures from B‐implanted,p+‐polycrystalline silicon gates upon annealing in the presence of H or F. This letter discusses the effects of TiSi2formation on B penetration through the gate oxide inp+polycrystalline silicon gate MOS devices. From secondary‐ion mass spectrometry analyses, it is found that B penetration effect is enhanced by TiSi2formation, for 950 and 1100 °C rapid thermal annealing, in spite of the fact that the F concentration in the gate oxide for samples with silicide is lower than that for samples without silicide. Furthermore, samples with a one‐step TiSi2formation process exhibit more serious B penetration effects than those with a two‐step process. This indicates that the effect of silicide on B penetration is more complicated than simply acting as a sink for F. Pileup of B at the silicide/polycrystalline silicon interface, the generation of point defects such as Si vacancies and interstitials during silicide formation, and B‐defect interactions must be taken into account to explain the results.

ISSN:0003-6951    

DOI:10.1063/1.104980

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Accurate knowledge of the shifts in valence‐ and conduction‐band edges due to heavy doping effects is crucial in modeling GaAs device structures that utilize heavily doped layers. X‐ray photoemission spectroscopy was used to deduce the shift in the valence‐band‐edge induced by carbon (ptype) doping to a carrier density of 1×1020cm−3based on a determination of the bulk binding energy of the Ga and As core levels in this material. Analysis of the data indicates that the shift of the valence‐band maximum into the gap and the penetration of the Fermi level into the valence bands exactly compensate at this degenerate carrier concentration, to give &Dgr;Ev=0.12±0.05 eV.

ISSN:0003-6951    

DOI:10.1063/1.104981

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Heavily boron‐doped (Na≳1×1019cm−3)Si epilayers grown on (100)Si by molecular beam epitaxy are investigated using double‐crystal x‐ray diffractometry. The variation of the Si lattice constant as a function of boron concentration is obtained from a combination of (400) rocking curve analysis and secondary‐ion mass spectrometry measurements on uniformly doped epilayers. This result is then used to determine the concentration profile in nonuniformly doped structures via dynamical simulations of experimental x‐ray rocking curves. The structures investigated include apipidoping superlattice and the results are found to be in excellent agreement with secondary‐ion mass spectrometry depth profiles.

ISSN:0003-6951    

DOI:10.1063/1.104982

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Time‐resolved photoluminescence (PL) spectroscopy has been performed on erbium‐doped Ga0.55Al0.45As. We have investigated the4I13/2→4I15/2optical transition. The measured fluorescence lifetime is around 1.2 ms which is similar to values found for other erbium‐doped III‐V compounds. Studies as a function of temperature indicate nonradiative transitions characterized by thermal activation of 40 meV. With the help of two beam experiments we have confirmed the existence of Auger losses during the PL excitation and a model of the excitation process is proposed that accounts for the experimental results.

ISSN:0003-6951    

DOI:10.1063/1.104983

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Raman scattering studies were performed on ZnSe‐ZnS strained‐layer superlattices with the incident light parallel as well as perpendicular to the interface plane. We found for the first time that the optical phonon modes split into two types, that is a singlet and a doublet, by the built‐in biaxial stress. A new method to characterize the directional stress is demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.104984

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Sputter removal of thin overlayers of Cu on Si was studied using 10 keV O+2primary ions at near‐normal incidence. The decay length &lgr;, which characterizes the exponential fall‐off of the Cu signal, was found to depend upon the carrier type, the dopant concentration, the polarity and strength of the electric field above the (ntype) samples, and the intensity of light directed at the (ptype) samples, the &lgr; values varying between 0.4 and 2.2 &mgr;m. A similar dependence on sample and bombardment parameters was observed for the ion‐induced electron emission coefficient &ggr; which ranged from 0.05 to 3 electrons/O+2ion. The results suggest that the internal electrical field strength established in the ion‐bombarded sample is largely determined by the effective rate of electron emission. The field strength across the oxide controls the transport of positively charged Cu impurities through this region and thus also determines the Cu removal rate.

ISSN:0003-6951    

DOI:10.1063/1.104985

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report the first observation of a nitrogen dangling bond center in nitrided thermally grown silicon dioxide films on silicon. Interpretation of the14N hyperfine parameters indicates that the unpaired electron wave function is strongly localized on the central nitrogen and that the wave function is highlypin character.

ISSN:0003-6951    

DOI:10.1063/1.104986

出版商:AIP    

年代:1991

数据来源: AIP