摘要:

A thermally stimulated current technique has been carried out to investigate the defect levels in Si‐ion‐implanted GaAs. Thermally stimulated current measurements have been performed in the temperature range of 90–300 K, and five deep traps with activation energies of 0.18, 0.20, 0.31, 0.40, and 0.43 eV have been observed. It is considered that the one of the traps (Ea=0.18 eV) shows the optical quenching effect and another trap (Ea=0.20 eV) is related to the damage due to the implanted ions.

ISSN:0021-8979    

DOI:10.1063/1.351377

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The solid phase epitaxial growth (SPEG) of amorphized Si layers implanted with Fe (1×1015cm−2, 100 keV) was investigated in the temperature range from 500 to 550 °C using Rutherford backscattering spectrometry. The push‐out of Fe atoms by the moving amorphous‐crystalline (a‐c) interface was observed during annealing, and enhancement of the recrystallization rate was induced by the presence of Fe. These results are discussed in terms of a model that assumes that Fe atoms are trapped in the amorphous layer and released when they are reached by the movinga‐cinterface during the SPEG process.

ISSN:0021-8979    

DOI:10.1063/1.350564

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Microstructures of silicon films deposited on SiO2substrates by low‐pressure chemical vapor deposition using Si2H6gas were investigated and compared to those using conventional SiH4gas by transmission electron microscopy and x‐ray diffraction. The deposition rate of the Si2H6process was about ten times higher than that of SiH4process at low temperatures (<550 °C). The transition deposition temperature from amorphous to polycrystalline film was found to be around 580 °C, which was similar to that of the SiH4process. The film deposited at 600 °C was partially crystalline and had equi‐axed grains with the largest average grain size of 0.3 &mgr;m while the films using SiH4has needle‐like columnar grains with smaller sizes (200 A˚). The x‐ray diffraction analysis showed that the structural disorder to amorphously deposited Si films increases as deposition temperature decreases. The grain size in the film after crystallization at 600 °C strongly depended on the deposition temperature and the deposition rate, producing a larger grain size at a lower deposition temperature and/or at a higher deposition rate (Si2H6deposition compared to SiH4deposition). The apparent increase in grain size can be explained as a result of the lowered number of crystal nuclei due to a decrease in the number of pre‐existing microcrystallites serving as heterogeneous nucleation seeds. When the deposition rate was lower than the critical value (approximately 2–4 nm/min), the grain size in the crystallized film decreased for both SiH4and Si2H6films. The maximum grain sizes were 4.5 and 0.3 &mgr;m at the deposition temperatures of 485 and 550 °C for the films using Si2H6and SiH4gases, respectively.

ISSN:0021-8979    

DOI:10.1063/1.350565

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The interaction of Cu with Si separated by thin (50 nm) layers of tantalum, Ta2N, and a nitrogen alloy of Ta has been investigated to determine the factors that affect the success of these materials as diffusion barriers to copper. Intermixing in these films was followed as a function of annealing temperature byinsituresistance measurements, Rutherford backscattering spectra, scanning electron microscopy, and cross‐section transmission electron microscopy. Ta prevents Cu‐silicon interaction up to 550 °C for 30 min in flowing purified He. At higher temperatures, copper penetration results in the formation of &eegr;‘‐Cu3Si precipitates at the Ta‐Si interface. Local defect sites appear on the surface of the sample in the early stages of this reaction. The Ta subsequently reacts with the substrate at 650 °C to form a planar hexagonal‐TaSi2layer. Ta silicide formation, which does not occur until 700 °C in a Ta‐Si binary reaction couple, is accelerated by the presence of Cu. Nitrogen‐alloyed Ta is a very similar diffusion barrier to Ta. It was found that Ta2N is a more effective barrier to copper penetration, preventing Cu reaction with the substrate for temperatures up to at least 650 °C for 30 min. In this case, local Cu‐Si reaction occurs along with the formation of a uniform Ta5Si3layer at the Ta2N‐Si interface.

ISSN:0021-8979    

DOI:10.1063/1.350566

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A detailed real time ellipsometry study of the growth of microcrystalline silicon (&mgr;c‐Si) films on transparent conducting oxide (TCO) substrates is presented. Indium tin oxide and ZnO substrates are compared. &mgr;c‐Si films prepared either from a high power (SiH4,H2) plasma or by alternating the SiH4and H2plasmas (layer‐by‐layer technique) are considered. Insights into the mechanisms of the TCO/&mgr;c‐Si interface formation are obtained. A strong chemical reduction of the TCO substrate is observed during the early stage of exposure to the (SiH4,H2) plasma. Then the ellipsometric measurements reveal an induction period of about 1 min before the nucleation of microcrystallites. &mgr;c‐Si films deposited by the layer‐by‐layer technique display a different behavior, in particular the chemical interaction at the ZnO/&mgr;‐Si interface is not observed in this case.

ISSN:0021-8979    

DOI:10.1063/1.350515

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The growth of SiC films on Si by reaction with tetraethyl silane (SiEt4) has been studied using Auger and electron energy‐loss spectroscopies, low‐energy electron diffraction, and external‐reflection infrared reflection absorption spectroscopy (IRRAS). IRRAS is used to monitor the chemisorption of the reagent molecule on polycrystalline Si at substrate temperatures below the point where complete dissociation occurs. The electron techniques are used to characterize the structure and composition of SixC1−x(0≤x≤1) layers formed on Si(100) at higher temperatures during dosing with SiEt4. Near room temperature, IRRAS data indicate adsorption of undissociated ‐C2H5groups with the C—C bond oriented nearly normal to the surface. Under growth conditions, the relative rates of deposition and indiffusion of C control the stoichiometry of the initial SixC1−xphase. At lower temperatures (∼750–1000 K), a partially noncarbidic phase occurs. Annealing this surface or dosing the clean surface at higher temperature leads to formation of a SiC layer which then acts to slow further diffusion. Subsequent layer growth occurs mainly by pyrolysis of the SiEt4molecule. However, the underlying Si substrate continues to function as either a C sink or a Si source.

ISSN:0021-8979    

DOI:10.1063/1.350516

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Titanium silicides prepared by codeposition at intermediate substrate temperatures with subsequent high temperature annealing were studied. It was found that coevaporation with Si/Ti ratio of 2.5 at the substrate temperature (Ts) of 120 °C results in the formation of an amorphous phase. On the other hand, samples prepared atTsof 300 °C resulted in crystalline TiSi2(C49). However, the amorphous phase was still present at the silicide/substrate interface. Considerable grain growth was observed to start at the silicide/Si interface even though the interfacial amorphous phase was the last to crystallize. It was suggested that Si diffusion is much more rapid through the amorphous silicide than crystalline TiSi2. This difference in kinetics was shown successful in explaining the dependency of the film properties of annealed samples on the structure of the product of the initial reaction.

ISSN:0021-8979    

DOI:10.1063/1.350517

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Single crystals of Bi2TeO5, both undoped and doped with transition‐metal‐ion dopants, were grown with high optical quality. Continuous‐wave four‐wave‐mixing experiments on these crystals show a strong photorefractive signal with a multicomponent decay. The photorefractive efficiency was studied as a function of the wavelength, intensity, polarization direction, and crossing angle of the laser write beams, and the sample orientation. Both absorption and phase gratings were observed with their relative strengths dependent on the laser wavelength and sample dopants. The signal evolves in time from a defect population grating, to trapped charge gratings involving two different types of traps, to fixed gratings produced by oxygen ion displacements. The photorefractive effect in this material is found to be of the photoconductive type and it produces a larger diffraction efficiency than that observed in sillenite materials under the same experimental conditions. A mechanism is proposed for the various physical processes leading to the different decay components of the signal.

ISSN:0021-8979    

DOI:10.1063/1.350518

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Diffusion of phosphorus into silicon from a doped spin‐on glass source using rapid thermal processing is described. The structural and electrical characteristics of the resulting shallow junctions including atomic and carrier concentration profiles, sheet resistance, as well as the effects on bulk carrier transport properties were studied and compared to those resulting from the use of conventional furnace heating. The results show that sheet resistance as low as 15 &OHgr;/&laplac; and surface carrier concentration higher than 1 × 1020cm−3are obtained in the annealed samples. Furthermore, a gettering effect is observed as the minority‐carrier diffusion length measured by the surface photovoltage technique is improved after processing.

ISSN:0021-8979    

DOI:10.1063/1.350519

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The electrical properties of as‐grown and heat‐treated copper indium diselenide (CuInSe2) thin films electrochemically deposited were measured in the temperature range 30 to about 300 K. In general the films showed variable range hopping conduction mechanism, i.e., &sgr;= (&sgr;0 T−1/2) exp[ − (T0/T)1/4] withT0between 4 × 102and 6 × 103K, at the lowest temperatures, and thermally activated conductivity, i.e., &sgr; = &sgr;0 exp( −Ea/kT) withEabetween 240 and 80 meV, over the temperature range close to the room temperature. The activation energy,Ea, decreased and the conductivity, &sgr;, increased with the annealing treatment. The data of these annealed films are in agreement with the Meyer–Neldel rule. Grain boundary trapping models were considered in the analysis of the results.

ISSN:0021-8979    

DOI:10.1063/1.350520

出版商:AIP    

年代:1992

数据来源: AIP