摘要:

The influence of the dwell-time in focused ion beam synthesis has been investigated. Cobalt disilicide layers have been produced by 70 keVCo2+implantation into silicon and have been investigated by Rutherford backscattering spectroscopy and scanning electron microscopy. At an implantation temperature of about 400 °C it is only possible to form continuousCoSi2layers using sufficiently short pixel dwell-times. This result is explained by an enhanced damage accumulation for longer dwell-times. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121110

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A method of improving the Al-bearing compound/GaAs interface against water vapor oxidation has been demonstrated. Amorphous native oxide formed by wet oxidation of an amorphous (Ga, As)/(Al, As) heterostructure on GaAs has exhibited an improved oxide/semiconductor interface with the incorporation of a thin GaP barrier layer of about two monolayers on the GaAs substrate. High resolution transmission electron microscopy shows an interfacial roughness on the order of 15 Å, and an enhancement of photoluminescence of three order of magnitude as compared to the as-grown counterpart without a GaP barrier indicates a great reduction in interface electronic traps. Having an improved interfacial roughness, a reduced interface trap density and an amorphous native oxide, this technique has a potential use in GaAs-based metal-oxide-semiconductor field-effect transistors. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121071

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Band gap measurements have been performed on strainedInxGa1−xNepilayers withx⩽0.12.The experimental data indicate that the bowing of the band gap is much larger than commonly assumed. We have performed first-principles calculations for the band gap as a function of alloy composition and find that the bowing is strongly composition dependent. Atx=0.125the calculated bowing parameter isb=3.5 eV,in good agreement with the experimental values. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121072

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

High-speed resonant cavity enhanced Schottky photodiodes operating in 800–850 nm wavelength region are demonstrated. The devices are fabricated in the AlGaAs/GaAs material system. The Schottky contact is a semitransparent Au film which also serves as the top reflector of the Fabry–Perot cavity. The detectors exhibit a peak quantum efficiency of&eegr;=0.5at&lgr;=827 nmwavelength and a 3 dB bandwidth of more than 50 GHz resulting in a bandwidth-efficiency product of more than 25 GHz. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121073

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The electroluminescence signal emitted from operating InP-based heterojunction bipolar transistors (HBT) is analyzed, giving clear evidence of ballistic electron transport through the base. The luminescence signal is studied as a function of base thickness, providing direct access to the ballistic electron mean free path. This continuous wave technique proves to be very efficient to measure ballistic electron scattering rates: 30 fs at 77 K and 19 fs at 300 K for a base Be doped to1019 cm−3.Quasiballistic transport range is found to be comparable to base width accessible by state of the art device technology, demonstrating its importance for ultrafast HBT operation. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121682

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Using three-source molecular beam epitaxy, we demonstrate the direct heteroepitaxial growth of the direct semiconductorCuInS2on silicon (001) substrates. The pretreatment of the silicon wafers includes a high-temperature exposure to the sulphur beam which leads to an ideal(1×1)sulphur-terminated surface defining the starting condition for successful epitaxy. All stages of the growth process were controlledin situusing Auger electron spectroscopy and low energy electron diffraction. Furthermore, the epitaxial layers were characterized by means of x-ray diffraction methods and by transmission electron microscopy. It is shown that theCuInS2epilayers grow with a tetragonal structure which is clearly distinct from chalcopyrite. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121074

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We present results from a kinetic Monte Carlo simulation of boron transient enhanced diffusion (TED) in silicon. Our approach avoids the use of phenomenological fits to experimental data by using a complete and self-consistent set of values for defect and dopant energetics derived mostly fromab initiocalculations. The results predict that, during annealing of 40 keV B-implanted Si at 800 °C, there exists a time window during which all the implanted boron atoms are substitutional. At earlier or later times, the interactions between free silicon self-interstitials and boron atoms drive the growth of boron clusters and result in an inactive boron fraction. The results show that the majority of boron TED takes place during the growth period of interstitial clusters and not during their dissolution. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121075

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Deep traps in the boron extended tail region of ion implanted 6H–SiCpnjunctions formed during annealing have been studied using deep level transient spectroscopy. Dramatically high concentrations of∼1016 cm−3of theDcenter have been observed through the unusual appearance of minority peaks in the majority carrier spectra. No evidence is found for any shallow boron acceptor in this region, but an induced hole trapIhatEV+0.46 eVis found under cold implantation conditions. These results support the picture of the extended tail, rich in boron-vacancy complexes such as theDcenter, which forms as a result of vacancy enhanced indiffusion. The dominance of the electrically activeDcenter in the depletion layer of the technologically important SiCpnjunction diode suggests the need for further research in this area. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121076

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Vertical cavity surface emitting lasers (VCSELs) are demonstrated with high-index-contrast native-oxide-based(AlxOy)distributed Bragg reflectors (DBRs) on both sides of a “2&lgr;” cavity, thus creating a compact (thin,∼2.8 &mgr;m) laser structure. Selective oxidation of high Al compositionAlxGa1−xAslayers yields a structure with a four period upperAlxOy/GaAsDBR, a 5.5 period lowerAlxOy/GaAsDBR, and a buried oxide current aperture. A reverse-biased tunnel contact junction provides hole injection via lateral electron current between the upper DBR and the oxide aperture layer. These VCSELs operate with submilliampere thresholds, high spontaneous efficiencies, and excellent polarization control. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121445

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Persistent photoconductivity effects have been characterized inn-typeAl0.15Ga0.85N/GaNheterostructures using both monochromatic light and room light illumination. Time constants of∼1×104 shave been observed, and measurements of photocurrent specta performed using various illumination geometries and techniques have shown that defect levels exist in both theAl0.15Ga0.85Nand GaN layers. Broad distributions of defect levels with excitation energies lower than the bandgap energies are found in bothAl0.15Ga0.85Nand GaN, and evidence is observed that these levels contribute significantly to the aforementioned persistent photoconductivity effects. The photocurrent spectra also reveal the presence of a level with an excitation energy of 3.36 eV that contributes to the persistent photoconductivity in the heterostructure. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121077

出版商:AIP    

年代:1998

数据来源: AIP