摘要:

Visible photoluminescence (PL) can be observed ina-SiOxanda-SiOx:Halloys prepared by evaporation of SiO in ultrahigh vacuum and under a flow of hydrogen ions, respectively. The hydrogen and oxygen bonding is studied by infrared spectrometry. The hydrogen stability is followed by thermal desorption spectrometry experiments. The evolution of the PL with annealing treatments shows that the PL can be attributed to a quantum confinement effect ina-Siclusters embedded in the matrix ofa-SiOx.Hydrogen does not greatly contribute to the PL efficiency and to the thermal evolution of thea-Siclusters. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121578

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

RelaxedGexSi1−xepilayers with high Ge fractions but low threading dislocation densities have been successfully grown on Si (001) substrate by employing a stepped-up strategy and a set of low-temperatureGeySi1−ybuffers. We show that even if the Ge fraction rises up to 90&percent;, the threading dislocation density can be kept lower than5×106 cm−2in the top layers, while the total thickness of the structure is no more than 1.7 &mgr;m. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121579

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

GaAs homointerfaces have been grown by molecular beam epitaxy using the steps of GaAs growth, As cap deposition, wafer storage, thermal desorption of the As cap, and GaAs overgrowth. As cap layers with a thickness of up to 7.8 &mgr;m were deposited and the wafers were stored for 3–7 days in ultrahigh vacuum (UHV) or under atmospheric conditions. Nonradiative recombination originating from the GaAs homointerface of wafers stored in UHV could not be detected (interface recombination velocityS≪1000 cm/s), however, significant nonradiative recombination(S=104–105 cm/s)was found for all GaAs homointerfaces where wafer storage occurred under atmospheric conditions. This result demonstrates that the As cap deposition/removal process is inadequate for GaAs surface protection in a fabrication facility. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121580

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Electron beam induced current measurements on planar Schottky diodes on undoped GaN grown by metalorganic chemical vapor deposition are reported. The minority carrier diffusion length of 0.28 &mgr;m has been measured, indicating minority carrier lifetime of 6.5 ns. The tapping mode atomic force microscopy imaging of the surfaces and scanning electron microscopy of the cross sections have been used to characterize the linear dislocations and columnar structure of the GaN. The possible influence of recombination on the extended defects in GaN on the minority carrier diffusion length and lifetime is discussed, and contrasted to other recombination mechanisms. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121581

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In this letter, we report a method called chemical bond manipulation for fabrication of multiperiod nanometer sizedSi/SiO2/Gelayered structure. Chemical bond manipulation is a self-organization process which involves selective breaking and making of surface chemical bonds and thereby enable formation of the desired species on a full wafer scale. We show that oxygen of germanium oxide layer formed on Si(111) are picked up by the Si atoms arriving at the surface during subsequent growth. This phenomenon involves breaking of Ge–O bonds and making of Si–O bonds and leads to the formation of ultrathin Si and Ge layers sandwiched between ultrathin silicon oxide layers, preserving the original wafer morphology. This material exhibits blue-green light emission at room temperature when excited by ultraviolet laser. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121582

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We demonstrate the dimensional tuning of InAs self-assembled quantum dots (QDs) by changing the growth kinetics during the capping of InAs islands with GaAs. Modifying the growth sequence during the capping of InAs islands, allows us to tune the thickness and lateral dimensions of the QDs while keeping the wetting layer thickness constant. Using the same method but embedding the tuned InAs islands into AlAs layers allows to further blueshift the photoluminescence emission to higher energies while keeping the wetting layer thickness constant. The main process responsible for the QDs size modification is consistent with a kinetically controlled materials redistribution of the InAs islands that minimizes the energy of the epitaxial layers at the start up of the GaAs capping deposition. ©1998 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.121583

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In this letter we report on a metal–semiconductor–metal photodetector based on thick relaxed Ge layers, epitaxially grown on silicon after insertion of a low-temperature-grown Ge buffer layer. The detector shows a good responsivity at normal incidence at both 1.3 and 1.55 &mgr;m, with a maximum responsivity of 0.24 A/W at 1.3 &mgr;m under a 1 V bias. A response time of about 2 ns has been measured. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121584

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Titanium (Ti) Schottky barrier diodes on epitaxially grown boron-dopedp-type Si films with a free carrier density of6–8×1016 cm−3were irradiated with alpha particles at room temperature using an americium-241 (Am-241) radio nuclide. We report the electronic and transformation characteristics of an &agr;-particle irradiation-induced defectH&agr;2in epitaxially grownp-Si with metastable properties. The energy level and apparent capture cross section, as determined by deep-level transient spectroscopy, areEv+0.43 eVand1.4×10−15 cm2,respectively. This defect can be removed and re-introduced using a conventional bias-on/off cooling technique. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121585

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We present a technique for the fabrication of materials integration of (100) silicon and (100) gallium arsenide by direct wafer bonding. GaAs wafers 3 in. in diameter were hydrophobically bonded to commercially available 3 in. silicon-on-sapphire wafers at room temperature. After successive annealings in hydrogen and arsenic atmospheres at temperatures up to 850 °C the Si/GaAs interfacial energy was increased by the formation of strong covalent bonds. Due to the difference in the lattice constants of about 4.1&percent;, extra Si lattice planes were observed at the interface. No threading dislocations were introduced into the GaAs. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121586

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The temperature-dependent optical properties of ZnTe epilayers grown on GaAs substrates by molecular beam epitaxy with and without ZnSe/ZnTe strained-layer superlattice (SLS) buffer layers have been studied using contactless electroreflectance (CER) and piezoreflectance (PzR). Our ZnTe epilayers of 1.5 &mgr;m in thickness grown on GaAs substrates are under a biaxial tensile strain according to the results shown in CER and PzR spectra. Furthermore, the strain induced energy splitting between heavy- and light-hole valence bands in the ZnTe epilayer can be reduced by using the ZnSe/ZnTe SLS buffer layers. We have also justified the temperature-dependent energy splitting between heavy- and light-hole valence bands for ZnTe through theoretical calculations. Discrepancy between experiments and calculations indicates that the residual mismatch-induced strain as well as the thermally induced strain during cooling must be taken into account at the same time. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121587

出版商:AIP    

年代:1998

数据来源: AIP