摘要:

Though copper can be quenched interstitially inp-type silicon, it precipitates completely within 10–15 h at room temperature. The decay of concentration of interstitial copper inp-Si was monitored by capacitance–voltage characteristics(C–V)and surface photovoltage (SPV). It is shown that the time constant of change of minority carrier diffusion length, as measured by SPV, correlates well with the precipitation of interstitial copper. The capture cross section of interstitial copper is estimated to be in the range10−15–10−17 cm2.It is shown that interstitial copper is far less deleterious than iron and can limit the diffusion length of commercialp-Si wafers only if its concentration is above1013 cm−3.However, copper precipitates may be detrimental to lifetime even for much lower copper concentrations. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119355

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The use of an Arrhenius plot of the temperature dependent current-voltage at some appropriate voltage leads to a temperature and voltage dependent activation energy, which is shown to be identical to the average energy carried by the electrons in flowing between the contacts separated by a quantum well structure. An optimal temperature range is limited by the highest temperature the system can tolerate without deleterious effects. The effective barrier height determined in a limited voltage rangeV⩽2(E1−Ef)/eis equal to the ground state energyE1, of the quantum well structure. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119356

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Spontaneously orderedGa0.47In0.53Asgrown on substrates with the (001) surface tilted4°towards{111}Bare studied using spectroscopic methods as well as x-ray diffraction, transmission electron diffraction and dark-field transmission electron microscopy. The single variant ordering is proved by the absence of one class of the ordering induced12{111}Bsuperlattice spots in transmission electron diffraction patterns as well as by the tilted polarization of the photoluminescence emerging from the samples cleaved edge. The temperature dependence of the luminescence peak position shows an anomalous behavior at low temperatures and a strong dependence of the peak position on the excitation power. From low temperature absorption measurements, we find a band gap reduction of 37 meV and a valence band splitting of 13.2 meV. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119357

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The Stokes shifts of the ground and the excited states in a crescent-shaped AlGaAs/GaAs quantum wire (QWR) are investigated using photoluminescence (PL) and PL excitation spectroscopy. The first excited electron to heavy-hole transition showed a Stokes shift (∼17 meV) considerably larger than that of ground state-related transitions (∼4 meV). This is a quite different phenomenon than that observed in two dimensional quantum well structures, and can be explained by the spatial separation of wave functions with different confinement energies in crescent-shaped QWRs. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119358

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

In a previous investigation, a diamagnetic band of the magnetic circular dichroism of the optical absorption (MCDA) in semi-insulating GaAs centered at 1.19 eV was observed and attributed to the neutral diamagnetic charge state of EL2,EL20.In this letter, we show a direct correlation between the signal intensities of two diamagnetic MCDA bands located at 0.93 and 1.19 eV and the concentration of neutral diamagneticEL20centers in different GaAs samples. A calibration factor is presented for the absolute MCDA intensities. This opens up the possibility of measuring the concentrations ofEL20andEL2+using the same technique. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119359

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The effect of implantation dose on microstructural development of the buried oxide (BOX) of 200 keV oxygen implanted Si was studied by electron microscopy. A continuous BOX layer with a low density of Si islands was obtained for a dose of0.45×1018 cm−2, following high temperature annealing. At a lower dose of0.225×1018 cm−2a layer did not form, but only disjointed, isolated, oxide precipitates developed. At a higher dose,0.675×1018 cm−2, a continuous BOX layer with a high density of Si islands formed. Microstructures of intermediate-temperature annealed samples showed the formation of oxide precipitates at preferred depths, the morphology being dose dependent. The final microstructure of the BOX is strongly influenced by the evolution of the oxide precipitates during annealing. A qualitative mechanism is proposed for the dose-dependent behavior of BOX formation during the annealing process. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.119360

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present a systematic study of atomic hydrogen passivation of Be doped AlGaAs/GaAs quantum well (QW) structures by photoluminescence spectroscopy. High quality AlGaAs/GaAs QWs with centrally doped Be acceptors have been subjected to dc H plasma at different sample temperatures and gas pressures. It is found that the percentage of deactivated Be acceptors strongly depends on sample temperature during H-plasma treatments and on the cooling down procedure after dc H-plasma treatment, while the duration of H-plasma treatments is less critical. Without causing degradation of the AlGaAs/GaAs interfaces, we have obtained a deactivation of up to 82&percent; of the Be acceptors. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119361

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The enhancement of secondary electron emission was observed for both heavily Si-implanted and heavily Si-doped GaAs after annealing at 950 °C. The enhancement was found to be related to the generation of Ga vacancy during annealing. The assessment of electrical properties of the enhanced area revealed that the enhancement arises from the secondary electron production process in the bulk region, not from the surface effect including band bending at the wafer surface. We suggested that the excitons produced by primary electrons would ionize the lattice defects introduced in ion implantation and/or annealing processes. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119362

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A substantial difference has been found in the initial incorporation mechanism of excess As into low temperature grown (LTG) (Al,Ga)As compared to LTG GaAs. In as-grown LTG GaAs the excess As initially incorporates as point defects (interstitials and/or antisite defects) resulting in an expansion of the lattice parameter. Only upon subsequent annealing does the excess As coalesce into precipitates, allowing the lattice parameter to relax back to its normal value. In contrast, as-grown LTG (Al,Ga)As shows no expansion of the lattice parameter until close to the maximum achievable excess As concentration has been reached, and most of the excess As is incorporated immediately as small precipitates. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119363

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We examine a defect in heat treated, oxidized 6H-SiC with electron paramagnetic resonance spectroscopy. Samples are examined before treatment, after oxidation, after dry (<10 ppmH2O)N2heat treatment, and after standard (approximately 50 ppmH2O) Ar annealing. A center is observed following dry heat treatment at temperatures greater than 800 °C. This center is passivated by standard Ar annealing at temperatures greater than 700 °C and regenerated after subsequent dry heat treatment. We suggest that this defect is related to an unpaired electron on a carbon atom created by the release of a hydrogen-related species. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119364

出版商:AIP    

年代:1997

数据来源: AIP