摘要:

p‐type ZnSe with resistivity low enough for device application has been realized by metalorganic molecular beam epitaxy. This method has enabled growth ofp‐type ZnSe doped with nitrogen at concentrations as high as 1019cm−3by using ammonia as a dopant source. The dependence of photoluminescence and electrical properties on substrate temperature has been investigated. Hall measurements showp‐type conductivity with a resistivity of 0.57 &OHgr; cm, a carrier concentration of 5.6×1017 cm−3, and a Hall mobility of 20 cm2/V s.

ISSN:0003-6951    

DOI:10.1063/1.102996

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Time‐resolved reflectivity and Rutherford backscattering spectrometry combined with channeling have been used to measure the epitaxial recrystallization kinetics of amorphous NiSi2and CoSi2layers. Epitaxial metal silicide layers, fabricated on (111) Si substrates by metal deposition and thermal reaction, were implanted with low‐energy Si ions to form amorphous surface layers. Such layers recrystallized epitaxially from the underlying crystalline metal silicide during thermal annealing at temperatures of 60–176 °C. Post‐anneal disorder consisted of dislocation networks as observed with transmission electron microscopy. Reduced recrystallization rates were apparent in samples implanted with O and Ar ions. Activation energies of 1.09±0.03 and 1.17±0.03 eV were determined for the epitaxial recrystallization of amorphous NiSi2and CoSi2layers, respectively.

ISSN:0003-6951    

DOI:10.1063/1.103229

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

In0.18Ga0.82As epitaxial layers having a thickness much greater than the established critical thickness of pseudomorphic layers have been grown on GaAs substrates. 0.25 &mgr;m gate metal‐semiconductor field‐effect transistors (MESFETs) are fabricated by silicon ion implantation into the epitaxial wafers. In spite of the large lattice mismatch and the high defect density, the devices show excellent device performance with a maximum extrinsic transconductance of 620 mS/mm and a current‐gain cutoff frequencyfTof 92.8 GHz. Furthermore, the Schottky gate characteristics of this device are shown to be comparable to those of GaAs MESFETs.

ISSN:0003-6951    

DOI:10.1063/1.102997

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Spontaneous and stimulated emission from a series of Al0.7Ga0.3As ‐Al0.49Ga0.51As‐GaAs ultrathin single [1,2, and 3 monolayer (ML), 1 ML=2.83 A˚] and multiple (2 ML) quantum well separate confinement heterostructures are demonstrated and compared to a control sample (0 ML). Spectra from sample to sample are very different and depend on the alignment of then=1, &Ggr; electron bound state in the quantum well with theXminima(lowest band edge) in the indirect‐gap (Al0.49Ga0.51As) confining layers. Some samples (3 ML single and 2 ML multiple quantum well) can support stimulated emission despite the fact that the quantum well is undoped, unstrained, and very thin (Lz≪scattering path length) and that most of the wave function is in the indirect‐gap confining layers. These experimental results can be explained using a simple model based on the spatial extent of the wave function (rather than the well width) under the special condition of band alignment between the &Ggr; andXstates.

ISSN:0003-6951    

DOI:10.1063/1.102998

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The chemical modification of hydrogen‐passivatedn‐Si (111) surfaces by a scanning tunneling microscope (STM) operating in air is reported. The modified surface regions have been characterized by STM spectroscopy, scanning electron microscopy (SEM), time‐of‐flight secondary‐ion mass spectrometry (TOF SIMS), and chemical etch/Nomarski microscopy. Comparison of STM images with SEM, TOF SIMS, and optical information indicates that the STM contrast mechanism of these features arises entirely from electronic structure effects rather than from topographical differences between the modified and unmodified substrate. No surface modification was observed in a nitrogen ambient. Direct writing of features with 100 nm resolution was demonstrated. The permanence of these features was verified by SEM imaging after three months storage in air. The results suggest that field‐enhanced oxidation/diffusion occurs at the tip‐substrate interface in the presence of oxygen.

ISSN:0003-6951    

DOI:10.1063/1.102999

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

In this letter the formation of Ti silicide on thin‐film silicon on insulator has been investigated. The experimental results indicated that uniform TiSi2layers with a low sheet resistance of 4.0–4.5 &OHgr;/&laplac; can be formed on thin‐film silicon on insulator with a high carrier concentration of 2×1020/cm3. So a structure of Ti/n+‐Si/SiO2/Si can be obtained. Secondary‐ion mass spectrometer profiles of the As showed that a relatively homogeneous redistribution of the As in the TiSi2layer is revealed and the As pileup at Si/SiO2interface is noticeable when the thickness of the silicon overlayer after the TiSi2formation is less than 520 A˚.

ISSN:0003-6951    

DOI:10.1063/1.103230

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Using a newly developed technique of shaped crystal growth from the vapor, we have obtained a lateral conformal GaAs single‐crystal growth between two Si3N4films. 0.6‐&mgr;m‐thick GaAs films of (100) surface orientation were grown over extensions of 15 &mgr;m in a standard arsenic trichloride vapor phase epitaxy reactor. The surface aspect of the films after removal of the top Si3N4layer is specular and these films are virtually dislocation‐free.

ISSN:0003-6951    

DOI:10.1063/1.103000

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Diamond films have been deposited on a variety of substrates up to 2 cm below the luminous plasma in a tubular microwave plasma‐enhanced chemical vapor deposition system. Depositing downstream of the plasma appears to offer several advantages over immersion of substrates in the plasma, for coating certain oxide substrates, including a reduction in substrate etching and an improvement in film uniformity, adhesion, and transparency. Furthermore, positioning substrates downstream of the plasma and adjusting their temperature with an external heater decouples the plasma and substrate parameters, facilitating studies to determine the effect of various parameters on the chemical vapor deposition diamond process. A disadvantage of downstream deposition is the decrease in the growth rate of diamond films.

ISSN:0003-6951    

DOI:10.1063/1.103001

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

IrSi3/p‐Si Schottky diodes have been fabricated by a molecular beam epitaxy technique at 630 °C. Good surface morphology was observed for IrSi3layers grown at temperatures below 680 °C, and an increasing tendency to form islands is observed in samples grown at higher temperatures. Good diode current‐voltage characteristics were observed and Schottky barrier heights of 0.14–0.18 eV were determined by activation energy analysis and spectral response measurement.

ISSN:0003-6951    

DOI:10.1063/1.103002

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have investigated the sidewall recombination in dry‐etched GaAs/GaAlAs wires with widths between 12 &mgr;m and 300 nm using picosecond spectroscopy. The wires were fabricated with electron beam lithography and different reactive ion etching processes. The excitonic lifetimes decrease strongly with decreasing wire widths due to sidewall recombination. Using a model calculation to fit the experimentally observed width dependence of the lifetimes the surface recombination velocity is determined to beS=2×106cm/s at 50 K.Sincreases with temperature and is independent of the etching process.

ISSN:0003-6951    

DOI:10.1063/1.103003

出版商:AIP    

年代:1990

数据来源: AIP