摘要:

Stranski–Krastanow islands of InP nucleate in straight rows when deposited by metalorganic vapor phase epitaxy on linearly patterned GaInP/GaAs surfaces. The patterns were produced by overgrowth of lithographically defined W stripes 30° off from [1¯10] on a GaAs(001) surface. Depending on the geometry of the grown GaAs/GaInP mesa stripes the islands were found to align either on top of the ridges, at the sidewall near to the mesa edge or at the bottom of the trenches. The highest density of almost equidistant coherent islands observed in some of the rows is in the order of 10 islands/&mgr;m, corresponding to a surface area density of 1010InP islands/cm2. The maximum density of randomly distributed islands in the unpatterned area otherwise is only 2×109islands/cm2. The results show a successful combination of overgrowth of conducting metal stripes and lateral geometrical positioning of dots in oneinsitugrowth step. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115905

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The influence of TiSi2formation on native Si point defects has been studied at temperatures between 800 and 890 °C. Sb and B in doping superlattices were employed to trace point defect behavior. Formation of TiSi2at 890 °C gives rise to an interface root‐mean‐square (rms) roughness of 22 nm. Ambiguities in the interpretation of the data arising from possible secondary ion mass spectroscopy artifacts due to sputtering through such a rough interface were avoided by etching the TiSi2film and replanarizing the Si surface. A rms roughness of 0.05 nm was obtained, as checked by atomic force microscopy and cross‐sectional transmission electron microscopy. We observed an enhancement in Sb diffusion and retardation of B diffusion over control samples without TiSi2. This indicates a vacancy supersaturation and an interstitial depletion in the Si due to the presence of the silicide. Possible mechanisms of vacancy creation and interstitial depletion are discussed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115906

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report a new type of damage, referred to here as inductive damage, induced by metal 1 plasma etching. The devices used in this study are lightly doped drainn‐channel metal–oxide semiconductor field effect transistors (MOSFETs) fabricated on 200 mmp/p+silicon wafers. The channel lengths of the investigated transistors are 0.5 &mgr;m with 90 A˚ thick thermally grown gate oxides. The metal 1 main etch (duration 30 s) and overetch (50%) employed BCl3/N2/Cl2chemistry and was done using a standard reactive ion etching tool operated at rf power of 600 W and rf frequency of 13.56 MHz. Specially designed MOSFETs with inductive metal loops connecting the gate and substrate or the gate and drain are used to examine inductive damage. Inductive damage is shown to arise from electrical stress of the gate oxide and oxide/Si interface by the electromotive force generated in the metal loops by the metal plasma etch. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115907

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have studied the influence of impurities on the dislocation behavior in heteroepitaxial layers of ZnSe on GaAs, grown by photoassisted organometallic vapor phase epitaxy. In undoped ZnSe layers, the dislocation densities are similar to those obtained by [S. Akram, H. Eshani, and I. B. Bhat, J. Cryst. Growth124, 628 (1992)] whose data show that there is an inverse relationship between layer thickness and dislocation density. Incorporation of the electronically active impurity Cl increases the dislocation densities relative to undoped layers of the same thickness. Also, there is a correlation between the normalized dislocation density and the concentration of incorporated Cl. The isoelectronic impurity Cd has a similar effect on the dislocation density. Incorporation of Cd to a concentration of ∼1020/cm3increases the dislocation density by a factor of about 3 compared to undoped layers of equal thickness. We also observed that doping of both Cd and Cl together resulted in low dislocation densities similar to the undoped case. Based on our results, we believe that the controlling factor for this phenomenon is the absolute value of the tetrahedral misfit for the impurity, rather than its sign, or the electronic activity of the impurity, or the sublattice on which the impurity resides. We propose an ‘‘impurity hardening’’ model to explain these results. According to this model the glide of dislocations is inhibited by the addition of impurities due to the local strain fields around the substitutional sites. The higher dislocation densities observed here with doping are an indirect result of impurity hardening. However, for single crystals or pseudomorphic heteroepitaxial layers, impurity hardening can inhibit the introduction of dislocations. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115908

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

During furnace N2O‐based silicon oxynitride growth, the total concentration of NOxspecies varies strongly with the flow rate of N2O. At low flow rates the N2O decomposes at least partially in the cooler region of the furnace near the gas inlet. This results in lower than expected NOx(x=1,2) concentrations in the oxidizing ambient. At high flow rates, the exothermic decomposition of N2O can heat the inlet region of the furnace, resulting in decomposition at a temperature above the nominal furnace temperature and higher than expected NOxconcentrations. These effects can lead to a substantial variation in the concentration of N in the oxynitride as a function of N2O flow. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115909

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Electric field‐induced second‐harmonic generation (EFISHG) is shown to be a very powerful method for contactless sampling of high‐speed electrical signals on silicon millimeter‐wave devices. We present picosecond resolution EFISHG measurements of 2 GHz sinusoidal signals on a photoconductive silicon‐on‐sapphire antenna. We further demonstrate the application of the EFISHG technique for spatial mapping of free‐running microwave signals in silicon. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115910

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

MBE regrowth on patternednp‐GaAs wafers has been used to fabricate GaAs/AlGaAs double barrier resonant tunnel diodes with a side‐gate in the plane of the quantum well. The physical diameters vary from 1 to 20 &mgr;m. For a nominally 1 &mgr;m diameter diode the peak current is reduced by more than 95% at a side‐gate voltage of −2 V at 1.5 K, which we estimate corresponds to an active tunnel region diameter of 75 nm ± 10 nm. At high gate biases additional structure appears in the conductance data. DifferentialI‐Vmeasurements show a linear dependence of the spacing of subsidiary peaks on gate bias indicating lateral quantum confinement. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115911

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Particles of 2–14 nm diameter, representing 10−4–10−3of the film volume, are observed by scanning tunneling microscopy (STM) in thin films of hydrogenated amorphous silicon (a‐Si:H) grown by rf‐plasma‐enhanced deposition using optimized conditions. The particles are produced in the discharge and incorporated in the film during growth, in contradiction to expected particle trapping by discharge sheath fields. The interfaces between the nanoparticles and the homogeneous film can produce low‐density regions that form electronic defects ina‐Si:H films. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115912

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We present the first study of a new system where the confinement potential of a high mobility quasi‐one‐dimensional electron gas on the (100) GaAs surface is varied using two, two‐dimensional hole gases produced on the adjacent (311)A surfaces. The structure consists of two lateral two‐dimensionalp‐njunctions, placed back‐to‐back to form ap‐n‐pstructure. The confinement potential of the narrown‐type channel can thus be modulated by applying a bias to the adjacentp‐type regions. Magnetoresistance measurements of the narrow channel show magnetic depopulation of the one‐dimensional subbands [K.‐F. Berggren, T. J. Thornton, D. J. Newson, and M. Pepper, Phys. Rev. Lett.57, 1769 (1986)], following the model of Berggrenetal. [Phys. Rev. B37, 10118 (1988)] widths and one‐dimensional carrier concentrations are extracted to fully characterize the dependence of the channel on the applied ‘‘hole‐gate’’ voltage. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115913

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Photoluminescence of GaInP epilayers under hydrostatic pressure is investigated. The &Ggr; valley of disordered GaInP shifts sublinearly upwards with respect to the top of the valence band with increasing pressure and this sublinearity is caused by the nonlinear dependence of lattice constant on the hydrostatic pressure. The &Ggr; valleys of ordered GaInP epilayers rise slower than that of the disordered one. Considering the interactions between the &Ggr; valley and foldedLandXvalleys, the pressure dependence of the band gap of ordered GaInP is calculated and fitted. The results demonstrate that not only ordering along ⟨111⟩ directions but also sometimes simultaneous ordering along ⟨111⟩ and ⟨100⟩ directions can occur in ordered GaInP. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115914

出版商:AIP    

年代:1996

数据来源: AIP