摘要:

A system and a procedure using chemical vapor deposition of silane at very low pressures (<10−2Torr) have been developed for depositing uniform, specular silicon epitaxial films both with and without plasma enhancement at temperatures as low as 650 °C.Insitucleaning of the substrate surface that overlaps into the deposition is the most critical aspect of the procedure. Undoped films deposited on substrates heavily doped with antimony or boron have abrupt doping profiles. Preliminary measurements indicate that the hole mobility of epitaxial films obtained with this process is 90% of that in bulk silicon. Films oxidized and decorated with a Secco etch show twice as many defects as a similarly treated substrate. Nonplasma growth kinetics are sensitive to surface conditions such as crystallographic orientation, and surface diffusion of adsorbed species appears to be the rate‐limiting step for depositing epitaxial films above 700 °C. Around 650 °C, the growth mechanism appears to change, possibly due to the increased presence of hydrogen on the surface. Finally, plasma enhances the growth rate, and plasma kinetics do not seem to be sensitive to surface conditions.

ISSN:0021-8979    

DOI:10.1063/1.335418

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Semi‐insulating polycrystalline silicon films have been grown by a low‐pressure chemical vapor deposition process between 565 and 623 °C. Rutherford backscattering spectrometry and nuclear reaction analysis were used to determine the layer composition and thickness. The O/Si concentration ratio in the films increases with increasing N2O/SiH4input for N2O/SiH4<0.6. For N2O/SiH4>0.6, a saturation effect in the oxygen uptake was observed. Furthermore the O/Si ratio increases with increasing growth temperature. The hydrogen concentration increases more than linearly with the N2O/SiH4input ratio for N2O/SiH4<0.5 up to an amount of 8.5 at. % at 600 °C. For N2O/SiH4>0.5 a saturation effect was observed in the hydrogen uptake. We suggest that the hydrogen is bound to silicon atoms, which are further coordinated with three oxygen atoms. Based on this model, the growth mode of the films at the temperatures considered is discussed.

ISSN:0021-8979    

DOI:10.1063/1.335419

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The reaction of Si (100) with C2H4from a molecular beam source has been studied using x‐ray photoelectron spectroscopy, electron‐energy‐loss spectroscopy, and Auger spectroscopy. Using these methods, we have studied the kinetics of SiC formation under conditions wherenogas‐phaseexcitationprocessescan contribute. At Si (100) temperatures below 940 K, a ‘‘Si‐C alloy’’ forms on the surface; annealing to higher temperatures produces SiC exhibiting electron spectroscopic properties identical to SiC (0001). By studies of the characteristic bulk‐ and surface‐plasmon‐loss features in the SiC thin film, it has been shown that surface aggregation of bulk Si on top of the growing SiC film occurs atT≥940 K. Under optimum SiC growth conditions, C2H4yields about 2×10−3SiC units per C2H4surface collision on Si (100).

ISSN:0021-8979    

DOI:10.1063/1.335420

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Using high resolution transmission electron microscopy, morphological aspects of the polycrystalline silicon (polysilicon)‐single crystal silicon interface have been correlated to the surface treatment used prior to polysilicon deposition, and to high‐temperature annealing. Specimens which were chemically oxidized prior to the deposition exhibited a continuous layer of amorphous oxide ∼15 A˚ thick; high‐temperature annealing results in the formation of small discontinuities in this oxide, and thus small regions of epitaxial realignment within the polysilicon layer. Specimens which were etched in HF prior to deposition were characterized by nearly oxide‐free interfaces, and, following high‐temperature annealing, exhibited regions of epitaxial realignment an order of magnitude larger than those found in the chemically oxidized samples.

ISSN:0021-8979    

DOI:10.1063/1.335421

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Variation of the effective distribution coefficientkeffwith the current densityJin electroepitaxy of semiconductor compounds is analyzed, taking into account the thicknessLof the solution. On the basis of the analytical expression for (keff−k0)/k0derived in this paper, wherek0is the interface distribution coefficient, both the changes in dopant concentration withJand the homogeneous distribution of dopants parallel to the growth direction are explained. It is shown that in electroepitaxy from a limited solution volume (L≲0.1 cm) the difference betweenkeffandk0is negligible even whenJbecomes very high. Thus, we can carry out direct measurements ofk0vsJin order to conduct a quantitative study of dopant incorporation mechanisms.

ISSN:0021-8979    

DOI:10.1063/1.335422

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Deep level transient spectroscopy and photoluminescence were used to study the effect of growth temperature (TG=550–650 °C) on high‐quality InP (ND−NA=1.5×1015cm−3; &mgr;77=41 000 cm2 V−1 s−1) grown by low pressure metalorganic chemical vapor deposition. A close relationship between deep levels and acceptor concentrations was found. Four electron traps were observed; not all of these traps have previously been observed in InP grown by metalorganic chemical vapor deposition. A metastable defect was detected in one of the samples.

ISSN:0021-8979    

DOI:10.1063/1.335423

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In this paper a comprehensive model of current conduction in polycrystalline silicon (polysilicon) based on the thermionic‐emission‐diffusion (TED) theory is developed, and on the basis of this model an expression for the effective majority carrier mobility &mgr;effis derived. This expression is quite general in nature and some thermionic emission (TE) theory based expressions for &mgr;effcan be obtained from it straightaway under certain simplifying assumptions. In addition, it helps in understanding the physical significance of the scaling factor used by earlier workers to explain their experimental results. Also, the experimental data on Hall mobility, which we obtained under an ohmic conduction regime in the 300–440 K temperature range for dark and illuminated conditions in lightly dopedn‐type polysilicon samples of different grain sizes, are presented and are interpreted on the basis of the TED model. Under strong illumination, the Hall mobility &mgr;HLwas observed to vary with temperatureTaccording to the relation &mgr;HL=aT−b, whereadepended on grain size and was found to be smaller for the smaller grain size. The dark mobility data fitted well into the TED‐based expression for &mgr;effconsidering the interface states associated with grain boundaries to be localized atEv+0.63 eV in the band gap. The analysis reveals that, generally, the scaling factor is needed if the effect of diffusion is neglected in comparison with the thermionic emission while in essence it is appreciable to be considered. However, in the TED model, as diffusion contribution in controlling the current transport across the grain‐boundary potential barrier is well taken care of, the scaling factor is not required.

ISSN:0021-8979    

DOI:10.1063/1.335424

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Sheet resistance and Hall effect measurements were made on graphite strip isothermally annealed antimony implanted (100) and (111) silicon. Although the (111) silicon annealed at lower temperatures, the (100) silicon achieved a lower sheet resistance (∼40 &OHgr;/&laplac; for a 3.8×1015cm−3dose) due to a greater activated carrier surface density. Supersaturated solid solutions were observed for both surfaces. At high active carrier concentrations (≳1×1020cm−3), the rapid decrease of mobility with increasing carrier concentration is attributed to ionized impurity scattering.

ISSN:0021-8979    

DOI:10.1063/1.335463

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The room‐temperature photoelectron kinetics in 1.3‐ and 0.4‐&mgr;m AgBr octahedral emulsion microcrystals have been investigated for time scales ranging from several nanoseconds to several microseconds after exposure. Two first‐order decay processes were observed in 1.3‐&mgr;m octahedra. The fast process is attributable to relatively shallow electron trapping that equilibrates with thermal detrapping after ∼60 nsec; the longer decay may involve ionic processes. Sulfur sensitization of the emulsion enhanced the fast electron decay rate (decay time=14 nsec). At higher levels of sulfur sensitization, the decay rate did not change with increasing sulfur levels; such behavior can indicate diffusion‐limited surface trapping. A bulk‐to‐surface electron drift mobility of 0.8 cm2/V sec on nanosecond time scales has been deduced from these kinetics. Implications of the data to current theories of photographic image formation and sulfur sensitization are discussed.

ISSN:0021-8979    

DOI:10.1063/1.335425

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The drift and Hall mobilities have been calculated for the scattering of electrons from donor‐acceptor pairs in a nondegenerate semiconductor. The separation between donor and acceptor has been correlated via a nearest‐neighbor distribution function and the impurity potentials modeled as screened coulomb interactions. By utilizing Alfred’s [Phys. Status Solidi B82, 467 (1977)] temperature‐dependent dielectric function, the mobility in the high‐ and low‐temperature regimes is obtained and compared with the dipole approximation of pair scattering in the Born approximation. The random pair approximation exceeds the dipole mobility by orders of magnitude for moderate dopant levels of, e.g., the order of 1016cm−3, and temperatures greater than 30 °K, indicating that the dipole approximation may be inadequate for most applications of interest.

ISSN:0021-8979    

DOI:10.1063/1.335426

出版商:AIP    

年代:1985

数据来源: AIP