摘要:

Amorphous Si is nucleated heterogeneously at grain boundaries during irradiation of polycrystalline Si thin films by 1.5 MeV Xe+ions for temperatures of 150–225 °C. Moreover, the heterogeneous nucleation kinetics of amorphous Si are strongly dependent on grain boundary structure. Following formation at grain boundaries, the amorphous Si layer grows at a rate comparable to that previously observed at a pre‐existing planar amorphous‐crystal interface. As amorphization proceeds, a decrease in average grain size and a marked change in the grain size distribution results. We suggest a simple atomistic model for amorphous phase formation in Si in which the nucleation kinetics are dependent on the point defect‐grain boundary interactions.

ISSN:0003-6951    

DOI:10.1063/1.102637

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Using low‐temperature photocurrent, steady‐state and time‐resolved photoluminescence, we have shown the importance of hole transport in the optical properties ofn+in+double‐barrier diodes under operation. We have also seen evidence of resonant tunneling of minority holes in such an illuminated double‐barrier diode.

ISSN:0003-6951    

DOI:10.1063/1.102638

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have imaged an AlGaAs/GaAs multiquantum well structure by scanning tunneling microscopy (STM). In order to localize the structure the STM is integrated in a conventional scanning electron microscope. The observed surface structure has a periodicity of ≊180 A˚ and shows an apparent corrugation of ≊10 A˚ in the constant current mode. We discuss the possible mechanisms of the observed contrast, which we tentatively attribute to the different electrical properties of the two different layers.

ISSN:0003-6951    

DOI:10.1063/1.102639

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have studied the morphology and distribution of atomic steps on Si(001) with scanning tunneling microscopy. We find that native oxide removal at temperatures up to 1350 K leads to step pinning and bunching. Cleaning at temperatures above 1450 K leads to regular step distributions which reflect the macroscopic misorientation of the sample. Steps running parallel to the 2×1 dimer rows on the upper terrace are straight, whereas steps perpendicular to these rows are ragged.

ISSN:0003-6951    

DOI:10.1063/1.102640

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have used electrolyte electroreflectance (EER) to characterize ZnSe/GaAs and ZnSe/AlAs interfaces. The great sensitivity of EER to interface space‐charge regions enabled us to detect both interface crossover transitions and transitions to triangular‐well interface states. The observation of these transitions provides the first unambiguous proof that the ZnSe/GaAs interface is type I and allowed us to determine the band offsets and band bendings, the diffusion lengths across each interface, and the amount of interdiffusion.

ISSN:0003-6951    

DOI:10.1063/1.102641

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have investigated strained InGaAs single quantum well structures using MeV ion beam methods. The structural properties of these structures, including composition and well size, have been studied. It has been found that the composition obtained by Rutherford backscattering spectrometry and particle‐induced x‐ray emission techniques agrees very well with that obtained by the ion channeling method.

ISSN:0003-6951    

DOI:10.1063/1.102642

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have fabricated GaAs/GaAlAs quantum wires with widths between 220 and 40 nm by high‐dose (2×1014cm−2) Ga implantation in a locally masked single quantum well structure. The width dependence of the emission energies indicates a steep 1D confinement determined by the lateral straggling of the implanted Ga. The external quantum efficiency of the wires increases strongly with decreasing mask width due to significant carrier capture from the lateral barrier.

ISSN:0003-6951    

DOI:10.1063/1.102643

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Si1−xGexand Si layers have been grown selectively in the exposed Si regions on oxide‐patterned ⟨100⟩ oriented Si wafers using the chemical vapor deposition technique limited reaction processing. Misfit dislocation spacings at the heterointerface were measured using plan‐view transmission electron microscopy in conjunction with a large‐area thinning technique which allows for examination of 100–150 &mgr;m diameter areas. The dislocation density is reduced by at least a factor of 20 for small areas (lateral dimensions: tens of microns) bounded by oxide isolation when compared to adjacent large areas (millimeters) which are uninterrupted by the patterned oxide. The ability to selectively grow Si1−xGexon patterned wafers and the area‐dependent reduction in dislocation density in as‐grown films may be important considerations for future device applications using Si1−xGexstrained layers.

ISSN:0003-6951    

DOI:10.1063/1.103176

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The density of misfit dislocation sources in strained Si1−xGexlayers grown on Si substrates is rarely sufficient to explain the observed extent of relaxation when layer thicknesses are in excess of the metastable critical thickness. This letter describes a process whereby a small, but finite number of misfit dislocation nucleation sources can lead to extensive strain relaxation across a complete wafer. Two novel mechanisms for misfit dislocation multiplication are presented and shown to be compatible with microscopic observations of chemically etched layers.

ISSN:0003-6951    

DOI:10.1063/1.102645

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The photoconductivity cyclotron resonance measurement is used to determine the effective masses of the high electron mobility transistor. The experimental data show that the effective mass is a function of the gate voltage.

ISSN:0003-6951    

DOI:10.1063/1.103184

出版商:AIP    

年代:1990

数据来源: AIP