摘要:

Trisdimethylaminoarsenic and phenylarsine have proven to be useful replacements for AsH3for growth of GaAs and AlGaAs by metalorganic molecular beam epitaxy. This paper will discuss the P analogs, namely, trisdimethylaminophosphorus (DMAP) and phenylphosphine (PhPH2), as well as trisdimethylaminoantimony (DMASb). All of these sources decomposed readily at the growth surface without precracking. InP surfaces were maintained with each source over a wide range, 375–525 °C, as were GaAs substrates over the range of 375–600 °C. Using DMAP, GaP was grown at rates up to 200 Å/min with slightly less carbon contamination than obtained with similar flows of PH3. When trimethylindium (TMI) or elemental In was introduced, however, neither the DMAP nor the PhPH2readily decomposed, thus leaving In droplets on the surface. InP was successfully grown by thermally cracking these compounds prior to injection to the chamber. The dependence of cracking efficiency and impurity uptake on cracker temperature will also be presented. DMASb was found to produce just the opposite effect of DMAP, apparently preventing the adsorption of triethylgallium, tri‐isobutylgallium, or trimethylaminealane on the surface for sufficient time to allow decomposition and hence growth to occur.

ISSN:0734-211X    

DOI:10.1116/1.587986

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

We studied the performance of a new type of valved cracking cell which contains a separate condensing reservoir and is intended for molecular beam epitaxy of phosphide compounds. The cell was designed to operate with a white phosphorus source, derivedinsituby sublimation and subsequent condensation of red phosphorus vapor. The parameters investigated were stability of the beam flux, switching transients, and growth chamber recovery time. The data show that a properly constructed valved cell, which incorporates a valve where shut‐off and metering are independently controllable, provides for a rapidly switched, stable beam flux with a minimum chamber recovery time. Aninsitugenerated white phosphorus source was found to reduce the P4burst accompanying the use of a red phosphorus source by over 300%.

ISSN:0734-211X    

DOI:10.1116/1.587987

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Surface x‐ray absorption fine structure experiments have been carried out on the system Si/GaAs(110) at coverages ranging from 0.8 to around 2 monolayers (ML) and at room temperature. Polarized experiments have allowed us to propose a model for the silicon adsorption site that has the initial silicon atoms sitting just above the middle of the As–As and Ga–Ga bond along the [001] direction. Above one monolayer, silicon atoms begin to be ordered with a siliconlike structure. At thicker coverages (above 3 ML) the silicon layer is amorphous, which permits a determination of the thickness probed by x‐ray absorption using the total electron yield technique.

ISSN:0734-211X    

DOI:10.1116/1.587988

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The chemical composition of GaAs(100) surfaces after HCl/H2O wet etching sequences has been examined with x‐ray photoelectron spectroscopy (XPS). XPS measurements show that oxides and chlorides are removed from the GaAs surface by the HCl solution etching in 10–20 min and subsequent H2O rinse in several seconds. The surface of the GaAs substrate thus prepared has been examined with atomic force microscopy. The surface flatness is so improved by the HCl/H2O treatment that the surface undulation remains within a ±1 monolayer fluctuation over a 1×1 μm surface area.

ISSN:0734-211X    

DOI:10.1116/1.587989

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

In molecular beam epitaxy an optical pyrometer is frequently used to determine substrate and epilayer temperatures during the growth of semiconductors. This implies a calibration of the pyrometer and a correct analysis of its indications. In this article we discuss problems presented by this calibration. We first compare the temperatures measured on the sample holder and on several substrates (GaAs, InAs, GaSb) attached to it. Then we present examples of temperature variations recorded during the growth of AlSb and GaSb on GaSb or GaAs substrates. GaSb epilayers thicker than 0.1 μm induce a 40°–60° decrease of the measured temperature. AlSb deposition on GaSb produces temperature oscillations. We discuss these variations in terms of apparent and true temperature variations.

ISSN:0734-211X    

DOI:10.1116/1.587990

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Metalorganic molecular beam epitaxy (MOMBE) growth is studied here for the first timeinsituwith reflectance anisotropy spectroscopy (RAS). Growth of AlAs on GaAs(001) and optical monitoring was performed in a standard MOMBE system. Triisopropylgallium, dimethyl‐ ethylaminoalane, and precracked arsine were used as precursors. RAS spectra obtained are similar to the ones observed under molecular beam epitaxy or metalorganic vapor phase epitaxy conditions and correspond to the GaAs(001) and AlAs(001)c(4×4) surface reconstructions. Initiating AlAs growth from an arsenic stabilizedc(4×4) GaAs(001) or AlAs (001) surface, the RAS signal shows oscillations with a period corresponding to the growth of one AlAs monolayer, as verified by thickness determination on thicker layers. As opposed to growth on an AlAs surface, when growing on GaAs the growth rate was not found to be constant right from the start, but was increasing slightly until it stabilized after several monolayers had been deposited.

ISSN:0734-211X    

DOI:10.1116/1.587991

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The scaling of etch rates with feature dimensions is an important issue in the fabrication of microelectronic and photonic devices. Because etch rates depend on circuit layouts and design rules, considerable effort is spent to modify processes each time changes in design are made. Knowing how etch rates scale with design parameters should accelerate the introduction of new designs into manufacturing while minimizing the cost of doing so. Recently it has been shown that etch rates for a variety of conditions scale with the depth/width or aspect ratio and not on width or depth alone. While various mechanisms might be responsible for such scaling, isolating one mechanism from another is not straight forward. Nonetheless, it is important to understand the underlying mechanisms so that differences in etch chemistry and etch reactor design can be accounted for when scaling plasma processes from one design or reactor to another. To assess the effects of etch chemistry alone, the trench etch rates of Si and GaAs are compared under constant plasma conditions. Substrate temperature is varied to further assess the relative importance of surface vs transport phenomena during the etching process.At higher temperatures, both Si and GaAs trench etch rates scale only with aspect ratio in an Ar/Cl2electron cyclotron resonance plasma. The results are consistent with an ion‐neutral synergy model based on Langmuir adsorption kinetics where the scaling can be explained by the aspect ratio dependence of the neutral reactant transport into the trench: charging effects, ion shadowing, and Knudsen transport are not consistent with the data. At −45 °C, the etch rate no longer scales with aspect ratio alone, but now also depends on trench width. The data at this lower temperature are well described by a model incorporating the deposition of an etch inhibiting layer. While the trench etch rates for GaAs and Si scale in similar ways with aspect ratio and trench width, the dependence on feature dimensions of the Si etch rate is much stronger than that for GaAs at all substrate temperatures because the steady‐state surface coverage of Cl is smaller for Si. This results in a greater sensitivity to the incoming, aspect ratio dependent, neutral fluxes. The implications of the models on the goal of aspect ratio independent etching are also discussed.

ISSN:0734-211X    

DOI:10.1116/1.587992

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

The formation and evolution of Si nuclei on the Si(100) surface at 600 and 700 °C were observed in a microwave electron cyclotron resonance plasma chemical vapor deposition system, using both real‐timeinsitusingle wavelength and spectroscopic ellipsometry combined with high‐resolution cross‐sectional transmission electron microscopy and secondary ion mass spectroscopy. The deposited Si layers are epitaxial, and decidedly different nucleation behavior is seen at 600 and 700 °C. The experimental ellipsometry results were compared with simulations and the results show that temperature has a profound effect on the initial nucleation and growth, and the different interface structures that are observed are attributable to impurities.

ISSN:0734-211X    

DOI:10.1116/1.588000

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

A Si contact layer for an electroluminescent (EL) diode was successfully grown on a Si1−xGex/Si single quantum well (SQW) layer by ‘‘hybrid’’ Si molecular beam epitaxy (MBE). The ‘‘hybrid’’ MBE was performed by growing the Si contact layer in a solid‐source MBE chamber after transferring the sample through air from a gas‐source MBE (GSMBE) chamber in which the starting SQW layer was initially grown by using disilane (Si2H6) and germane (GeH4). The growth characteristics of the hybrid MBE were investigated byinsitumonitoring of the reflection high energy electron diffraction. A (2×1) reconstruction was observed even after the sample was exposed to air for up to 15 h on a GSMBE‐prepared Si(100) surface. Evidence of the excellent quality of the EL device was provided by the sharpest emission lines, a full width at half maximum of ≊5.5 meV. The spectral features of the EL and photoluminescence were found to be almost identical, and a well‐resolved acoustic phonon replica was observed. Linear polarization for a no‐phonon replica of EL was also observed along SQW plane.

ISSN:0734-211X    

DOI:10.1116/1.588002

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Silicon dioxide films were deposited in an electron cyclotron resonance plasma onto substrates at temperatures ranging from 65 to 200 °C. In order to determine the effect of ions on the deposition, both ion flux and ion energy were investigated. The ratio of ion flux to deposition flux was found to be a significant parameter and this ‘‘flux ratio’’ was varied between 8 and 100. Mean ion energy was investigated at 10, 50, and 75 eV. The silicon dioxide films were characterized by measurement of wet etch rate, density, composition, and stress, and by infrared spectroscopy. It was found that above a flux ratio of about 20, high‐quality SiO2was deposited whether or not the substrate was thermally floating or at 65–200 °C, indicating that the flux ratio was dominant over the temperature. Use of radio‐frequency bias to increase the mean ion energy to 50 eV or above was effective in producing high‐quality SiO2when the flux ratio was below 20, but not as effective as using a high flux ratio. Thus high ion flux and low ion energy were found to be useful in producing SiO2at temperatures as low as 65 °C with properties close to that of thermal silicon dioxide. The role of ions in the deposition process was found to be densification, removal of –OH (or hydrogen) and alteration of Si–O bonding.

ISSN:0734-211X    

DOI:10.1116/1.588003

出版商:American Vacuum Society    

年代:1995

数据来源: AIP