摘要:

The reaction of sputter deposited layers of Ti on the (001) surface of a synthetically grown single crystal type IIb boron doped diamond has been investigated using Auger electron spectroscopy with depth profiling, Rutherford backscattering spectroscopy (RBS) and Raman spectroscopy. Electrical characteristics of the contacts were measured usingI–Vdata and separated from substrate electrical effects using Hall measurements of the carrier concentration and mobility. Heat treatments above 425 °C were found necessary to cause the transition from a rectifying to an ohmic contact. Without a protective 150 nm layer of Au, oxidation of the Ti layer was observed atT≥425 °C, even for annealing in forming gas. This was detrimental to the adhesion of the layer and the long term stability of the ohmic contact resistance. With a protective Au film, low resistance, adherent ohmic contacts were observed even after 1 h at 750 °C, even though Ti diffused along Au grain boundaries to form nodules of TiO2at the Au/ambient interface. Interfacial carbides were detected by both Auger peak shape changes and RBS measurements for annealing temperatures as low as 500 °C, and their appearance correlated with the transition to ohmic contacts. The carbides increased in thickness to about 50 nm after 1 h at 750 °C.

ISSN:1071-1023    

DOI:10.1116/1.587549

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

n‐metal–oxide semiconductor field effect transistors (MOSFETs) were fabricated with plasma enhanced metalorganic chemical vapor deposited Ta2O5gate oxide on Czochralski grown Si wafers using localized oxidation of silicon isolation technology by the conventional Si‐based process. The Ta2O5gate oxiden‐MOSFETs showed excellent electrical characteristics such as subthreshold swing of 68–74 mV/dec, transconductance of 4 μS/μm for 4 μm gate length, and carrier mobility of 400 cm2/V s at the saturation region. The largeCoxof the gate oxide with the high dielectric constant, εr=20–25, allowed the higher drain current of the device. During the whole process ofn‐MOSFET fabrication, the cross sectional transmission electron microscopy analysis of the Ta2O5/Si interface showed SiO2interfacial oxide formation of about 35 Å thick. The Ta2O5gate oxiden‐MOSFET showed good performance compared to the high‐temperature silicon oxide gate devices and thus has great potential for applications in the electronic devices.

ISSN:1071-1023    

DOI:10.1116/1.587550

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Electron cyclotron resonance hydrogen plasma and argon plasma was used to clean Si surface without additional heating within 4 min and 30 s, respectively. Changes in the electrical properties after plasma treatment with different exposure times have been studied and compared using a Schottky diode structure. The reverse saturation current of the Schottky diodes changes less in the case of the hydrogen plasma cleaned samples than the argon plasma cleaned samples. After hydrogen plasma exposure, residual hydrogen introduced into the Si was found to enhance greatly the formation of thermal donors which induces considerable changes in the defect states after annealing. After annealing at ∼450 °C in N2, new defects, caused by thermal donors, appear and these defects decrease significantly at 750 °C. Defects in the argon plasma treated samples annihilate after annealing at 1000 °C for 1 h.

ISSN:1071-1023    

DOI:10.1116/1.587551

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The structural and electrical properties of highly Sb‐doped molecular beam epitaxy grown silicon have been investigated as function of rapid thermal annealing (RTA) temperature. Doping levels of 3×1020cm−3were obtained using low temperature epitaxy (LTE) performed at a growth temperature of 300 °C. Ion channeling and transmission electron microscopy (TEM) measurements showed that the as‐grown samples were of very high quality. The combination of Hall‐effect profiling and Rutherford backscattering spectroscopy revealed an electrically active Sb fraction of 0.8. Short time RTA processing improved the electron mobility and the activation: RTA at 600 °C for 10 s yielded unity activation and RTA at 800 °C gave mobilities matching phosphorus doped bulk values, thus significantly exceeding previously reported values for highly doped LTE material. A degradation of the crystalline quality was observed for higher RTA temperatures: RTA at 1000 °C for 10 s reduced both the Sb‐substitutional fraction and electrical activation to 0.6 due to precipitation of Sb, and lead to the formation of a high density of dislocation loops as observed by TEM. A large fraction of the precipitates decorated these dislocation loops. Mesa isolated diodes were fabricated to evaluate the use of LTE material for device production. Current–voltage measurements on these diodes revealed high quality junctions with low reverse currents and near‐ideal forward characteristic.

ISSN:1071-1023    

DOI:10.1116/1.587552

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

High‐frequency spark discharges were applied to single‐crystalline wafers of Ge, GaAs, and Si. The spark‐processed (sp‐) samples were characterized by photoluminescence (PL) and Raman measurements. Strong and stable luminescence with wavelengths centered at 416 and 525 nm was observed in sp‐Ge and sp‐Si layers, respectively, when excited with a 325 nm laser beam. A considerable blue shift of the PL (compared to the unsparked specimen) was also detected for sp‐GaAs with an average peak wavelength around 500 nm. The Raman shifts of the spark‐processed materials indicate that nanocrystals were formed, having diameters of 3.5–4 nm for Si and about 6 nm for Ge. A correlation between the PL wavelengths, the nanocrystal sizes, and the different semiconductor materials has been established based on the effective‐mass approximation. Making use of this model the nanocrystallite sizes have been found to range between ∼3 nm for Si and ∼5 nm for Ge. The related wavelengths for optical transitions confirm the PL results. The findings support the quantum confinement model.

ISSN:1071-1023    

DOI:10.1116/1.587553

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The damage behavior of Si induced by MeV Ge+under tilted angle has been studied. In order to investigate the effect of implanted energy and angle on the damage distribution, the energies were varied from 1 to 2 MeV and the angles were varied from 7° to 60°. The experimental damage distribution is extracted based on the procedure by Feldman and Rodgers [L. E. Feldman and J. W. Rodgers, J. Appl. Phys.41, 3776 (1970)] using the multiple‐scattering model. The experimental data obtained are compared with the TRIM’90 code. The results show that the lateral damage spread can not be neglected; the shape and the depth of damage distribution are well described by the TRIM’90 code under tilted angle irradiation for Si(100).

ISSN:1071-1023    

DOI:10.1116/1.587554

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

High‐resolution synchrotron radiation photoemission has been used to examine the oxidation states of Si atoms near the Si/SiO2interface. The quality of the starting Si surfaces was intentionally varied and oxidation was done with pure O2and with a mixture of O2plus Cl2. The distribution of intermediate oxidation states and the interface thickness was unaffected by Cl2exposure for atomically flat, well‐ordered Si(100) or (111) surfaces. However, for disordered Si surfaces the presence of Cl2in the oxidizing gas reduced the concentration of Si1+and Si2+species by a factor of 2, indicating a tendency to produce better interfaces. In all cases, Cl was present near the SiO2/Si interface, bonded to Si, and in solution with SiO2as Cl2.  

ISSN:1071-1023    

DOI:10.1116/1.587555

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Application of the simulated annealing and downhill simplex methods to the design of electrostatic monopole‐and‐quadrupole circular plate systems is investigated. The design objective is to minimize chromatic, relativistic, and third‐ and fifth‐order geometric aberrations subjected to a set of predefined source parameters, source and image locations, and maximum allowed electrode potentials. Instead of searching for some optimal potential distributions, which may be extremely difficult to reconstruct in practice, a geometrically simple system consisting of circular plates is arbitrarily chosen at the start. These circular plate electrodes are each partitioned into four separate sectors so that a mixture of axially symmetric (monopole) and quadrupole fields can be generated by each individual plate. An algorithm for rapid repeated computations of the field and potential distributions is outlined. Methods of simulated annealing and downhill simplex are then invoked to find a locally optimal monopole and quadrupole potentials combination to achieve the smallest image spot size of an axial point source. Several promising results have been observed. The combination of monopoles and quadrupoles can achieve spot sizes more than two times smaller in radius than those obtained with just monopoles or quadrupoles alone. Finally, the patterns and properties of the optimal monopole and quadrupole potentials are studied in detail to gain some insight into the ideal general system behaviors and interactions.

ISSN:1071-1023    

DOI:10.1116/1.587556

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Carbon thin films produced by electron beam sublimation deposition and solvent liftoff have been used as reactive ion etch masks for etching deep trenches on InP. Using a Cl2:HBr:BCl3:Ar‐based plasma in a reactive ion etcher, 15‐μm‐wide trenches were etched to a depth of 18 μm. The etch rate selectivity between InP and the carbon mask is better than 100:1. The resulting sidewall profiles are highly anisotropic due to the low sputter rate of carbon.

ISSN:1071-1023    

DOI:10.1116/1.587557

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

We demonstrated the proof of principle for the fabrication of trenches with widths down to 0.1 μm on a silicon substrate using photolithographically prefabricated starting mask structures having a spacing of 0.6 μm. The corresponding trench width of 0.15 μm was achieved using starting mask structures having a spacing of 1.0 μm. Chemical‐beam deposition of metals was used to coat the starting mask structures and to narrow the aperture openings. Metal redeposition by ion‐beam sputtering directed perpendicular to the substrate further narrowed the spacing between the sidewalls of the mask structures. The subsequent chemically assisted ion‐beam etching of the underlying substrate through the constricted mask apertures produced the trenches with greatly reduced widths.

ISSN:1071-1023    

DOI:10.1116/1.587558

出版商:American Vacuum Society    

年代:1994

数据来源: AIP