摘要:

Insituphosphorus doped Si epitaxial layers have been grown at 600 °C in a very low pressure chemical vapor deposition system, using SiH4and PH3diluted in H2. The presence of H2was found to decelerate the epitaxial growth rates. Secondary‐ion mass spectrometry measurement shows that the constant phosphorus concentration with depth for a steady flow of PH3was achieved. Namely, dopant concentration is a function of gas phase dopant concentration. Chemical concentration as high as 2.5×1020P/cm3was obtained in Si epitaxial layers though with very low growth rate. Epilayers with constant doping levels from 1.5×1018P/cm3to 1.2×1020can readily be grown. Despite the relatively low growth rate, there is no evidence of a time‐dependent accumulation of phosphorus on the growth surface or the reactor wall. The reasons accounting for this phenomenon are discussed.

ISSN:0734-211X    

DOI:10.1116/1.589005

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The x‐ray photoelectron spectroscopy (XPS) technique has been used to investigate the composition of semi‐insulating polycrystalline silicon (SIPOS) films having oxygen contents of 10 and 35 at. % prepared by low pressure chemical vapor deposition. XPS analysis has demonstrated that the film compositions can be qualitatively described by means of the five Si‐SixO4−xtetrahedra (with 0≤x≤4 and integer) predicted by the statistical random bonding model (RBM). However, the quantitative analysis of the XPS spectra has demonstrated that the concentrations of the various tetrahedra found in the SIPOS films are remarkably different from those predicted by a statistical approach, i.e., by assuming that each Si atom forms with equal probability bonds with either Si or O. We have also found that the composition of high temperature (up to 1000 °C) annealed films further departs from that predicted by the RBM model; indeed, the anneal promotes the decomposition of partially oxidized Si‐SixO4−xtetrahedra in Si‐Si4tetrahedra (that form Si nanocrystals) and Si‐O4tetrahedra (that enrich the oxygen content of the amorphous phase).

ISSN:0734-211X    

DOI:10.1116/1.589006

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Design specifications for plasma immersion ion implantation systems are discussed. An analytical model of the plasma sheath evolution is used to deduce restrictions for the dimension of the vacuum chamber and the pressure range. The avoidance of arcing implies an upper limit for the maximum electric field in the sheath and hence for the plasma density. The total fluence per pulse, which determines the implantation duration and the power requirement, is calculated. Furthermore, safety considerations, especially the shielding of x‐rays generated by secondary electrons, are discussed.

ISSN:0734-211X    

DOI:10.1116/1.589007

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The native oxidation of As‐implanted Si surfaces used in actual ultralarge scale integrated processes are investigated. Quantitative analysis of oxidation is made possible by x‐ray photoelectron spectroscopy spectral decomposition of Si 2pinto Si4+, Six+, and Si0+, and by calculation of SiO2and SiOxthicknesses using the decomposition results. Here, the sensitivity is such that less than 1 Å change is detectable. The native oxidation of As‐implanted (1×1015–1×1016/cm2, at 25 kV) Si(100) is compared to that of Si(100) without implantation. The results show that the oxidation rate of As‐implanted Si is faster than that of Si without implantation, that the native oxide on As‐implanted Si includes more suboxide than that on Si without implantation, and that As is oxidized in deeper regions than Si. These results indicate that As implantation changes the Si native oxidation mechanism itself. We propose an oxidation model of As‐implanted Si to explain our observations, and discuss the validity of this model.

ISSN:0734-211X    

DOI:10.1116/1.589008

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We have shown that quantitative determination of metal trace impurities in the range between 109cm−2and 1012cm−2on top of the native oxide of a Si wafer by laser postionization of sputtered neutrals in combination with time‐of‐flight mass spectrometry (Laser‐SNMS) and time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) is possible. Trace metal standards with concentrations in the range between 109cm−2and 1012cm−2were used for calibration. These standards were prepared by sputter deposition and were independently controlled by Total Reflection X‐Ray Fluorescence Analysis. Relative sensitivity factors for 12 metals on Si for Laser‐SNMS were determined. Additionally, we compared postionization with different wavelengths (193 nm and 248 nm). With Laser‐SNMS it was then possible to determine the influence of UV/ozone treatment on the measured surface concentration of metal species. The UV/ozone treatment is necessary to achieve high and reproducible useful yields for the metal species in TOF‐SIMS. With this knowledge, we were able to determine relative sensitivity factors for the metals on UV/ozone‐treated Si wafer surfaces measured by TOF‐SIMS. Detection limits down to 108cm−2and 1012cm−2for sample surface areas of 100 μm in diameter and 1 μm in diameter, respectively, were found for both Laser‐SNMS and TOF‐SIMS.

ISSN:0734-211X    

DOI:10.1116/1.589009

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The scattering effects (specifically LO‐phonon scattering) in a 45 Å AlAs/80 Å GaAs/33 Å AlAs asymmetric double barrier resonant tunneling (ADBRT) structure with a short period GaAS/Al0.3Ga0.7As superlattice incorporated on one side of the double barrier have been studied and characterized. Enhanced levels of current conduction were produced in the ADBRT due to the superlattice miniband electron transport under forward bias. And the effect of the said superlattice on the phonon scattering phenomena exhibited by the entire device was subsequently examined. Magnetic field fan diagrams at 4.2 K under reverse bias showed a new feature at an energy of 22 meV that could be explained on the basis of previously unreported GaAs LO‐phonon scattering processes from the first excited emitter level. Finally, quenching of phonon‐assisted tunneling in reverse bias on decreasing the period of the superlattice was also observed.

ISSN:0734-211X    

DOI:10.1116/1.589010

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Extra facet generation during molecular beam epitaxy of GaAs/AlGaAs multilayers on (001) GaAs substrates patterned with stripes running in the [1̄10], [110], and [100] directions and having various slopes, designated as ‘‘[1̄10]stripe,’’ ‘‘[110] stripe,’’ and ‘‘[100]stripe,’’ respectively, has systematically been investigated for the first time. It has been confirmed that extra (111)A and (114)A facets are generated on the [1̄10] stripes, extra (1̄11)B and (1̄13)B facets on the [110]stripes, and extra (031), (011), (045), and (013) facets on the [100] stripes, depending on the intersection angle θ of the sidewall and the substrate plane. Among them, the (114)A, (1̄13)B, and (013) facets are important because they persist over a wide range of θ and, therefore play a detrimental role in forming flat and uniform sidewall layers on the (001) patterned substrates. It has been made clear that no extra facets are generated on the sidewalls and flat and uniform layers maintaining the initial as‐etched stripe patterns can be grown for the [1̄10]stripes with 10°≥θ, the [110] stripes with 24°≥θ≥20°, and the [100]stripes with 19°≥θ. Extra (111)A‐related facets have developed on the (111)A‐related intersection of the equivalent [100] and [010]stripes, while no extra facets have developed on the (1̄11)B‐related intersection. The facet generation behavior has been compared between the (001) patterned substrates and previously studied (111)A patterned substrates.

ISSN:0734-211X    

DOI:10.1116/1.589011

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

In this work, InP/InGaAs single heterojunction bipolar transistors (SHBTs) with excellent performance were grown by solid‐source molecular beam epitaxy using a phosphorus valved cracker. The maximum dc and differential current gain are ∼27 and 32 with breakdown voltagesVceo∼6 V andVcbo∼10 V for the SHBT with a 5000 Å InGaAs collector layer doped at 4×1016cm−3. The ideality factors forIbandIcare ∼1.12 and 1.07 and the transistors also show very uniform current gain down to 10−10A range. For high frequency performance, the maximumfTandfmaxare around 80 and 125 GHz for the SHBT with an emitter area of 32 μm2.

ISSN:0734-211X    

DOI:10.1116/1.589012

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Arsenic incorporation during GaAs/GaAs(100) molecular beam epitaxy is studiedinsituwith laser single‐photon ionization time‐of‐flight mass spectrometry and reflection high‐energy electron diffraction (RHEED). Incident and scattered fluxes of Ga and Asnspecies in front of the growing GaAs wafer are ionized repetitively by a pulsed laser beam of 118 nm (10.5 eV) photons. The methods to obtain and interpret time‐of‐flight mass spectra and the simultaneous RHEED measurements are described. The real time behaviors of incident Ga and desorbing As2and As4, obtained without mass spectral cracking, are studied during growth of GaAs layers with As4and when growth is arrested as a function of substrate temperature and Ga/As4flux ratio. During growth only with As4, both As2and As4are desorbed or scattered in varying amounts depending on flux and substrate temperature conditions. Without an incident gallium flux, desorbing As4decreases while desorbing As2increases with increasing surface temperature. During gallium deposition and GaAs growth, the amounts of desorbing arsenic fluxes decrease linearly with increasing Ga/As4flux ratio, but the arsenic incorporation rate saturates at a Ga/As4flux ratio ≥2, i.e. (Ga/As≥1/2). The total integrated incorporation of arsenic increases linearly with increasing Ga/As4flux ratio when the surface is allowed to recover with an incident arsenic flux after the gallium flux is terminated. In the range of substrate temperatures optimum for layer‐by‐layer GaAs growth with As4, As4incorporation dominates at low temperatures, while As4and As2incorporations contribute equally at high temperatures. Surface reaction sequences and mechanisms of arsenic incorporation are discussed and compared with measured RHEED results and previous experimental and theoretical results.

ISSN:0734-211X    

DOI:10.1116/1.589013

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We report the growth and characterization of 1.55 μm wavelength GaInAsP based semiconductor lasers grown by solid source molecular beam epitaxy. Quaternary compositions were reproducible over time. Photoluminescence and x‐ray diffraction spectra indicate abrupt quantum well interfaces. Separate confinement heterostructure laser diodes with four quantum wells had threshold current densities as low as 580 A/cm2and 275 A/cm2for unstrained Ga0.47In0.53As and strained Ga0.27In0.73As0.8P0.2wells, respectively. These results are as good as the best results reported for similar lasers grown by any growth technique.

ISSN:0734-211X    

DOI:10.1116/1.589014

出版商:American Vacuum Society    

年代:1996

数据来源: AIP