摘要:

Spatially resolved concentration profiles of ground‐state oxygen atoms in O2/Ar plasmas have been obtained under loaded etching conditions through the use of a two‐photon laser excitation process. These results provide a quantitative measure of the reactive atom concentration gradient during etching of kapton or graphite on the rf‐driven electrode. The effects of load, ion bombardment, and diffusion on the reactive atom concentration may be directly monitored by thisinsitu, unobtrusive, three‐dimensional probe technique.

ISSN:0021-8979    

DOI:10.1063/1.337109

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We investigate an analytical model for concentration profiles of reactive gas‐phase species adjacent to surfaces, as determined by optical probe techniques. The model is illustrated with measurements of CF2, detected by laser‐induced fluorescence, above silicon and other substrates. Conditions under which the model is applicable are discussed.

ISSN:0021-8979    

DOI:10.1063/1.337110

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The potential of ferroelectric liquid crystals for application as pyroelectric infrared detectors is examined. The liquid crystals studied belong to a family of biphenyl and phenylbenzoate esters. It is found that even within this first liquid‐crystal family examined, the materials figure of merit compares well with ferroelectric solid materials commonly used for infrared detection and imaging. Because they permit very simple and flexible device design, liquid crystals are attractive candidates for these applications. However, for low‐frequency applications, attention must be paid to the reduction of thermal loading by the cell walls.

ISSN:0021-8979    

DOI:10.1063/1.337111

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The activation efficiency of conventional furnace annealing (550–750 °C, 30 min, capless, AsH3/H2ambient) and rapid thermal annealing (800 °C,∼1 s, SiO2cap, N2ambient) has been compared in Be‐doped Ga0.47In0.53As by investigating the carrier profiles and the atomic profiles. Nearly complete activation (100%) occurs during both 750 °C furnace annealing and rapid thermal annealing for an implanted fluence of 6×1013Be ions/cm2. At a fluence of 6×1014Be ions/cm2a significantly higher activation (>50%) is found after rapid thermal annealing as compared with furnace annealing (30%) mainly due to out‐diffusion of Be during furnace annealing. Low‐temperature photoluminescence (2 K) revealed that comparable recrystallization is achieved in both methods. A high diffusivity of Be is apparent in the atomic depth profiles after furnace annealing. However, only insignificant redistribution is noticeable after rapid thermal annealing, probably due to gettering of the diffusing Be by defects.

ISSN:0021-8979    

DOI:10.1063/1.337058

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The conductivity enhancement in polydiacetylene (PDA) crystals due to chemical doping and ion implantation was measured and analyzed in relation to their spin concentration and photocurrent decay based on the structural and optical information obtained through infrared and visible reflectivity spectra. A conductivity jump was observed upon slight increase of the spin concentration at low doping levels of chemically doped PDAs, suggesting the formation of spinless carriers in chemically doped PDAs, as intrans‐polyacetylene and poly(p‐phenylene). In contrast, in ion‐implanted samples, a great difference in the magnitudes (by more than five orders of magnitude) was observed between the conductivity enhancement for two PDAs having different side chain species. Furthermore, the photocurrent decay time measurements reveal different distributions of implantation‐induced trap levels between ion‐implanted poly [2,4‐hexadiyne‐1,6‐diol‐bis‐(p‐toluene sulfonate)] (PTS) and poly[2,4‐hexadiyne‐1,6‐di(N‐carbazolyl)] (DCH). A conduction mechanism which could explain the significant difference in conductivity enhancement between PTS and DCH is suggested. Because the enhanced conductivity by ion‐implanted PTS showed no orientational effect associated with the polymer chain direction, a conductive path and network formation by the implantation‐induced defects is more plausible for the conduction mechanism than carrier introduction into the backbone chain band from side chain defect levels.

ISSN:0021-8979    

DOI:10.1063/1.337059

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We have measured implanted and annealed depth distributions for the two elements adjacent to Si, Al, an acceptor in Si, and P, a donor in Si, using secondary ion mass spectrometry for the atom depth distributions and differential capacitance‐voltage profiling for the acceptor or donor depth distributions. Ions of Al or P were implanted into Si amorphized by Si implantation, into crystalline Si in a random orientation, and channeled into the three principal low index directions of the Si lattice, ⟨100⟩, ⟨110⟩, and ⟨111⟩. The ion energies were 25, 50, 75, 100, 150, 200, 300, 400, or 600 keV and the ion influences were 3×1013, 3×1014, and 3×1015cm−2for the atom depth distributions, and 1.5×1012cm−2for the acceptor and donor profiles. Pearson IV fitting was used to obtain the values of the first four moments of the random depth distributions, the projected rangeRpor &mgr;, the range straggle &Dgr;Rpor standard deviation &sgr;, the skewness &ggr;1, and the kurtosis &bgr;2. For the channeling orientations, the maximum channeling range or the depth of the channeled peak are plotted versus ion energy, and values of the energy exponentpare determined. The random rangesRpand profiles are compared for amorphized and crystalline Si and compared with range calculations; the profiles in amorphized Si are modified Gaussians as predicted by theory, with no channeling tails, and the profiles in crystalline Si have significant channeling tails that are not easily fit to a modified Gaussian. The different channeling profiles for Al and P are illustrated and explained in terms of their different electronic stopping and ion size. The effects of 30‐min furnace annealing at 550 and 800 °C are shown for implanted Al profiles; significant redistribution occurred, and in a manner that depends on Al atom density and whether the Si is amorphous or crystalline. Furnace annealing at 875 and 925 °C or rapid radiant annealing at 900 °C caused no redistribution of P profiles implanted at room temperature.

ISSN:0021-8979    

DOI:10.1063/1.337060

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Acceptor depth distributions measured using differential capitance‐voltage profiling, and atom depth distributions measured using secondary ion mass spectrometry are reported for aluminum implanted in the random and the ⟨100⟩, ⟨110⟩, and ⟨111⟩ directions of the silicon crystal in the ion energy range from 5 to 300 keV, and show agreement between the two measurements for selected energies and with one prior work. Values of range parameters, maximum channeling ranges, and electronic stoppingSeare reported.

ISSN:0021-8979    

DOI:10.1063/1.337061

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

High and low densities of 300‐keV Ag atoms were implanted into (100) and (111) crystalline and self‐amorphized Si, and annealed at temperatures from 100 to 900 °C and for various times. Silver depth distributions were profiled using secondary ion mass spectrometry. Regrowth locations and rates of the various damaged regions were measured with good sensitivity via the Ag profiles, which resulted from the retention of Ag atoms by defect complexes and their release upon annihilation of the defect complexes during annealing. The following results were obtained for (100) Si: regrowth toward the surface of the 0.3‐&mgr;m‐thick amorphized layer beginning at about 450 °C, up to 650 °C, with a regrowth rate of (18±2) A˚/°C or 5.2 A˚/min at 530 °C; regrowth of the amorphous‐crystalline interface region at 850 °C at a rate of (8±1) A˚/min. The presence of 2×1019cm−3Ag atoms retards the regrowth rate of (100) Si by a factor of 2. Two separate, but closely spaced regions of residual damage in the amorphous–crystalline interface region were revealed. Regrowth of (111) Si occurs uniformily in depth throughout the amorphized region, consistent with the growth of polycrystalline or microtwinned Si in this region as seen by transmission electron microscopy.

ISSN:0021-8979    

DOI:10.1063/1.337062

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The rapid thermal annealing (RTA) behavior of Be+‐ion‐implanted AlxGa1−xAs is investigated by means of Hall‐effect and photoluminescence (PL) measurements. The electrical activation in GaAs occurs from 400 °C and saturates at about 450 °C, while in AlxGa1−xAs alloys, the activation fractions increase gradually with increase in the annealing temperature. These fractions are evidently smaller in the AlxGa1−xAs alloys than in the GaAs, and largerxalloys give smaller activation fractions at any fixed temperature. PL intensity measurements indicate that annealing at 900 °C results in the maximum optical activation and lattice recovery both for GaAs and AlxGa1−xAs alloys. Secondary ion mass spectrometry (SIMS) analysis reveals Be accumulation at the AlxGa1−xAs (0≤x≤0.3) / SiO2encapsulant interface caused by Be out‐diffusion during RTA. SIMS and differential Hall‐effect measurements also suggest significant Be in‐diffusion in AlxGa1−xAs alloys especially for largerxvalues.

ISSN:0021-8979    

DOI:10.1063/1.337063

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The phase retardation‐extremum method offers a fast and simple way to measure the pretilt angle of nematic liquid crystal (NLC) cells. Due to optical absorption of the dissolved dyes, such a method is not suitable to measure the pretilt angle of a guest‐host (GH) NLC cell. We have obtained a simple and fast method to determine the pretilt angle of a GH NLC cell from the incident angle corresponding to the minimum transmission intensity of a polarized light passing through the GH cell. Using this simple method, we have measured the pretilt angles of GH NLC cells with different dye concentrations, and compared them with the pretilt angles of the corresponding host NLCs measured by the retardation‐extremum method. Excellent agreement between the two methods was observed with a dye concentration of not more than 1%. Within our experimental errors, dye concentration of up to 5.8% (by weight) seems not to change the pretilt angle of the GH NLC from that of the corresponding host NLC.

ISSN:0021-8979    

DOI:10.1063/1.337064

出版商:AIP    

年代:1986

数据来源: AIP