摘要:

We study the growth of amorphous (a‐Si:H,F) and of microcrystalline (&mgr;c‐Si) silicon over trench patterns in crystalline silicon substrates. We vary the conditions of the SiF4‐H2glow discharge from deposition to etching. All deposited films form lips at the trench mouth and are uniformly thick on the trench walls. Therefore, surface diffusion is not important. The results of a Monte Carlo simulation suggest that film growth is governed by a single growth species with a low (∼0.2) sticking coefficient, in combination with a highly reactive etching species.

ISSN:0021-8979    

DOI:10.1063/1.345600

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Single‐ and multiple‐energy Be+/P+, Be+/Ar+, and Be+/N+coimplantations were performed into semi‐insulating InP:Fe. Significantly higher Be dopant activations were obtained for Be+/P+and Be+/Ar+coimplantations compared to Be+implantation. Sharp hole‐concentration depth profiles were obtained for Be+/P+and Be+/Ar+coimplantations in contrast to the deep diffusion fronts for Be+implantation. A high degree of crystalline lattice damage in coimplanted material is believed to be responsible for the improved electrical characteristics of the material. A poor Be dopant electrical activation was observed for Be+/N+coimplantation.

ISSN:0021-8979    

DOI:10.1063/1.345601

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The formation of buried single crystalline CoSi2layers within a monocrystalline Si substrate by high‐dose ion implantation of Co has been studied. Comparison of measured Co distributions with profiles obtained from Monte Carlo calculations has revealed the two basic phenomena that are responsible for the formation of buried layers. The enhanced stopping due to the incorporation of high concentrations of Co into Si has been identified as the dominant effect in the ion beam synthesis of buried layers. The high stopping near the top of the implanted distribution causes accumulation of Co at this point, which promotes buried layer formation. Sputtering brings the entire Co profile closer to the surface. After implantation at a temperature of 450 °C, Co is present in the form of coherent CoSi2precipitates. Precipitates occur both in a twinned and an aligned orientation and are highly strained due to the lattice mismatch with Si. For high doses a buried monocrystalline and aligned CoSi2layer forms within the Si lattice, during implantation. Annealing of the implanted structures results in the formation of a buried layer when, near the top of the implanted distribution, more than 50% of the Si is converted into CoSi2. These layers too are monocrystalline and have on aligned orientation. Cobalt diffusion in the Si lattice has been suggested to be the rate‐determining step in the growth process of the buried layers. Finally, the electrical properties of these ion beam synthesized structures exhibit some unique features.

ISSN:0021-8979    

DOI:10.1063/1.345602

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The incorporation of Si in ion‐implanted and thermally annealed GaAs has been studied by local vibrational mode spectroscopy. Raman scattering and Fourier transform IR absorption have been used to analyze the Si site distribution both in the near surface region and averaged over the whole implanted layer, respectively. The samples implanted with doses of 5×1014–1016cm−2were annealed with various techniques using different capping layers. The Si site distribution is found to depend strongly on the details of the annealing. In particular, capping with SiO2leads to the formation of the so‐called Si‐Xdefect complex in addition to the incorporation of Si on both lattice sites and the formation of nearest‐neighbor Si pairs.

ISSN:0021-8979    

DOI:10.1063/1.345603

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It has been recently demonstrated that it is possible to significantly alter the maximum power input required for mechanical failure of glass used for high average power laser applications by employing an ion exchange process that does not alter the optical properties of the strengthened glass. We present the analysis of the thermal stresses, fracture, and strengthening for the experimental geometry used. From this analysis the fracture strength of the untreated and treated glass can be estimated. Some suggestions for the control of thermal stresses during the operation of solid‐state lasers using glass slab geometries are presented. The second part of this report presents a micromechanical analysis of the strengthening effect due to the ion exchange process in which the enhancement in fracture strength is correlated to the depth of the zone in which ion exchange has occurred, to the length of microscopic flaws present on the surface of the glass, and to the magnitude of the microscopic volume expansion due to the ion exchange process. In particular, we consider the cases where the depth of the treated zone is much smaller or much greater than the depth of surface flaws. The magnitude of the enhancement in fracture strength is calculated in terms of these microscopic quantities for some material properties typical of phosphate glasses.

ISSN:0021-8979    

DOI:10.1063/1.345604

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Arsenic and phosphorus codiffusion was studied using a buried boron layer. Analysis of the dopant profiles was performed using secondary ion mass spectroscopy, spreading resistance profiles, and junction staining. Contrary to expectations, the profiles of arsenic and phosphorus diffused by themselves were enhanced over the codiffused profiles. The buried boron profile in the case of phosphorus alone was enhanced over the boron profile in the case of arsenic and phosphorus codiffusion. The residual annealing of implantation damage is thought to be responsible for these effects. In addition, the suppression of the self‐interstitial supersaturation for codiffused conditions is a transient effect and is postulated to be caused by an increase in recombination of implantation‐generated vacancies and self‐interstitials due to the presence of a high concentration of arsenic atoms.

ISSN:0021-8979    

DOI:10.1063/1.345605

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

TheT0curve of the Si‐As system has been determined by pulsed laser melting of supersaturated solid solutions in the As concentration range between 0 and 12.5 at. %. Samples were irradiated with both 20‐ns 347‐nm‐wavelength and 20‐ps 532‐nm‐wavelength laser pulses, and surface melting has been revealed by time‐resolved reflectivity measurements. Melting temperatures of the solutions have been derived from the measurement of the energy absorbed at melting threshold. Some implications of our results on the thermodynamics of the Si‐As system are discussed.

ISSN:0021-8979    

DOI:10.1063/1.345606

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The influence of ion mass and dose on the intermixing of GaAs/GaAlAs quantum‐well structures using photoluminescence (PL) and secondary‐ion‐mass spectroscopy (SIMS) techniques has been studied. Ga, Zn, Ar, Mg, Ne, and He ions are implanted in a single‐quantum‐well (SQW) structure at different doses. After annealing, the amount of intermixing between Al and Ga is extracted from the PL peak energy shift of the near‐band‐gap emission of the SQW. The measured Al diffusion length values &Dgr;Alfor different ion species agree with a simple model which assumes that the implantation damage in conjunction with lowT(T<600 °C) defect diffusion is responsible for the mixing. We observe a similar dose dependence for &Dgr;Alfor all the above ions. For high implantation doses we have studied the mixing by Ar ions after implantation and annealing with SIMS. The SIMS data indicate that at high doses collisional mixing is the dominant mechanism for the disordering. Drastic mixing effects are obtained in the above quantum‐well structures after high‐temperature annealing of samples implanted with electrically active impurities (S,Si).

ISSN:0021-8979    

DOI:10.1063/1.345607

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The origin of the motion of semiconductors during ion mixing was investigated by studying both the temperature and the atomic mass dependence of moving species in the GexSi1−x/Ni and the GexSi1−x/Pd systems. Ion mixing was performed with 280‐keV Ar ions at temperatures between 30 K and room temperature. The atomic mass of the GexSi1−xalloy was adjusted by changing the concentration of Ge in the alloy. In thermally induced reactions, no preferential motion of Si or Ge was observed. During ion mixing, the atomic flux of Si was observed to be enhanced compared to that of Ge. The atomic flux of the sum of Si and Ge to metal decreases with increasing substrate temperature during mixing and with increasing Ge concentration in the GexSi1−xalloy. From the strong atomic mass dependence of the moving species during ion mixing it is concluded that the origin of the motion of semiconductors under ion mixing conditions is due to the effects of secondary recoils.

ISSN:0021-8979    

DOI:10.1063/1.345608

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The TiSi2/Si system is investigated using high‐resolution transmission electron microscopy (HRTEM) and electron diffraction in both cross‐section and flat‐on modes. The results show that the large crystallographic differences between both crystals and the complexity of the reaction path are not obstacles to the formation of flat and well‐defined interfaces. (1¯01) TiSi2proves to be a preferential plane for epitaxial growth on Si (111). In this case, the terminal TiSi2plane at the interface is composed of single atomic species. It is proposed that the reasons leading to such an epitaxy are related to the small discrepancy of atomic densities and interplanar spacings characteristic of these planes. Observation of local epitaxial relationships are reported and investigated using a lattice matching model. It turns out that they minimize the two‐dimensional misfit at the interface.

ISSN:0021-8979    

DOI:10.1063/1.345609

出版商:AIP    

年代:1990

数据来源: AIP