摘要:

The deposition of Te on an already deposited Ag film and of Ag on a Te film results in a homogeneous Ag‐Te alloy as a result of fast Ag diffusion (4×105A˚2sec−1at 300 K). In the case of Ag‐Te, when the diffusion proceeds at 200 K, the resulting diffusion couple is amorphous.Insituresistance measurements suggest that the same Ag diffusion mechanism operates when Ag atoms or Ag films are in contact with Se (7.3×104A˚2sec−1at 253 K), S, or I. The major difference with the Ag‐Te case is that in the latter cases, even when the Ag diffusion proceeds at low temperatures (?200 K), the resulting diffusion couples are always crystalline Ag2Se, Ag2S, or AgI.

ISSN:0021-8979    

DOI:10.1063/1.331145

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Recent optical and photoelectric data of Zn3P2single crystals are reviewed including measurements of oriented crystals under polarized light. A Zn3P2band‐structure model is proposed which is based on these results. The influence of tetragonal crystal structure is included in the model as the additional split‐off valence level and two different minima in the conduction band near the &Ggr; point.

ISSN:0021-8979    

DOI:10.1063/1.331146

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Experimental data are reported for the persistent photocapacitance quenching observed at 77 K in GaAs. This effect, which arises on the so‐called oxygen (or EL2) center in gallium arsenide, is explained by the existence of two states of this center. The physical parameters of these stable and metastable states are given: optical cross section, annealing, and electrical deexcitation. Assuming a large lattice relaxation for the metastable one, a physical model is given with a possible microscopic origin. Other striking memory effects, and especially photoconductivity, are shown to be simply explained by our model.

ISSN:0021-8979    

DOI:10.1063/1.331147

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

High dose implantations of boron molecular ions such as BF+2and BCl+2ions in Si have been investigated in an attempt to form shallow P+layers in the dose range 1×1015–1×1016ions/cm2, in comparison with those of boron. For BF+2implants it was found that both the effective surface carrier densityNsand junction depthXjin Si after 1000°C anneal tend to completely saturate at doses above 5×1015ions/cm2, while they tend to increase for B+implants. From profile measurements of total and electrically active boron it was clarified that the additional implantation of BF+2ions in excess of 5×1015ions/cm2results in the accumulation of inactive boron atoms particularly around the surface region. Junction depths in Si resulting from BF+2implants are generally shallower than those resulting from B+implants. For BCl+2implants the values ofNsare generally much lower than those for BF+2and B+implants.

ISSN:0021-8979    

DOI:10.1063/1.331148

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Modulation‐doped Ga0.47In0.53As/Al0.48In0.52As single period heterostructures were prepared by molecular beam epitaxy. Current versus electrical field characteristics were investigated in a lattice temperature range of 10–300 K. Measurements were performed at electric field strengths as high as 2 kV/cm which is comparable to the field strengths attained in normally‐off field effect transistors. Mobilities as high as 8960 cm2/Vs at 300 K, 61 100 cm2/Vs at 75 K, and 93 000 cm2/Vs at 10 K were measured and were found to be proportional to temperature approximately as &mgr;∝T−1.74. Mobility enhancement was observed in the single period Ga0.47In0.53As/Al0.48In0.52As system irrespective of the relative position of the larger band gap Si‐doped Al0.48In0.52As.

ISSN:0021-8979    

DOI:10.1063/1.331149

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Annealing of acceptor dominated &agr;‐Al2O3atTsat= 1100–1500 °C in atmospheres containing hydrogen leads to dissolution of hydrogen, changing the material fromp‐ ton‐type when the concentration of hydrogen donors is larger than that of the acceptor impurities present. If oxygen equilibrium is maintained, the concentration of ionized donors depends onpH2as well aspO2(orpH2O). In measurements of dc conductivity in atmospheres not containing hydrogen, a contribution to the conductivity by mobile protons rapidly disappears as a result of polarization. Analysis of the rate of polarization leads to values for the concentration and mobility of mobile protons. In measurements in atmospheres with well‐defined hydrogen and oxygen fugacities, protons, native ions, and electrons and holes contribute continuously to the conductivity. Transference numbers of the various species and the corresponding partial conductivities were determined by emf measurements. The amount of dissolved hydrogen increases with decreasing temperature of saturation, increasing hydrogen pressure, and increasing oxygen pressure. Attempts to find detailed defect models explaining the results were only partially successful.

ISSN:0021-8979    

DOI:10.1063/1.331150

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The presence and the location of a band of acceptor levels at the surface of the high‐resistivity GaAs (Cr doped) and the GaAs/oxide interface is studied, using two‐beam Transverse Acousticoelectric Voltage (TAV) spectroscopy. This study is not feasible by conventionalC‐Vmethods due to the high resistivity of GaAs samples. The band of acceptor levels, centered around 1 eV above the valence band is detected nondestructively. The anodic oxides are grown electrochemically using different current densities (0.1–3 mA/cm2) under constant current regime. The interfacial characteristics of the GaAs/oxide is compared by the two‐beam TAV spectroscopy. The results show a lower density of interface states for the oxides grown at lower current densities. To explain the presence of the acceptor band above the midgap in all of the tested samples, the physical models proposed by different authors are presented and compared.

ISSN:0021-8979    

DOI:10.1063/1.331151

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The x‐ray induced photocurrent in the thermal SiO2layer of a Metal‐SiO2‐Si (MOS) structure consists of two components: (1) contact photoinjection and (2) bulk generation. It has been found, both theoretically and experimentally, that the relative importance of the contact photoinjection component increases with decreasing oxide thickness. For a 500‐A˚ SiO2, the contact photoinjection is approximately equal to the bulk generation over a wide range of oxide fields (105–2×106V/cm) and starts to dominate for oxides thinner than 300 A˚. The earlier internal photoemission theory developed for UV photon energies below the SiO2band gap can be used to describe the observed voltage dependence of the contact photoinjection current under x‐ray irradiation, and good agreement between the theory and the experiment has been established. Onsager’s theory of geminate recombination is shown to satisfactorily explain the field dependent generation rate in SiO2over the field range 105–2×106V/cm. These findings are important to the understanding of the ionizing radiation effects in MOS structures where carrier injection and generation play an essential role.

ISSN:0021-8979    

DOI:10.1063/1.331152

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Photocurrent measurements using sub‐band‐gap light on low dopedn‐type gallium arsenide are described. Measurements of photocurrentIas a function of depletion widthWand wavelength &lgr; were made to determine minority carrier diffusion lengthsLof order 1 &mgr;m. For long wavelengths (&lgr;≳0.879 &mgr;m)I(W) plots could be used to measureLfor carrier concentrationsn?2×1015cm−3. For larger values ofn, whenW≳L, the method was inapplicable owing to nonlinearities in the plots. The mean change in absorption coefficient, &Dgr;&agr;, at &lgr; = 0.8907 &mgr;m was determined from the plots as a function of electric field and was in qualitative agreement with calculations of the expected variation due to the Franz–Keldysch effect. It is shown that the measurements ofI(&lgr;) may be used to determineLforn<5×1015cm−3provided accurate absorption coefficient data are available. A correction for the Franz–Keldysch effect is necessary for 2×1015<n<5×1015cm−3. For 5×1015<n<1016cm−3the method is inapplicable, whenW≳L, owing to nonlinearities caused by the Franz–Keldysch effect.

ISSN:0021-8979    

DOI:10.1063/1.331153

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

For the mixed perovskite oxide system (Sr0.8125La0.1875) (Zr0.75FexRu0.25−x)O3−&dgr;, electrical conductivities were measured in air as a function of temperature and Ru/Fe ratio. Liquidus and solidus temperatures were determined in air by the laser melting point measurement technique. The substitution of Ru for Fe was found to increase the electrical conductivity by over an order of magnitude while decreasing the solidus temperature of the Fe‐rich solid solution by less than 10%.

ISSN:0021-8979    

DOI:10.1063/1.331154

出版商:AIP    

年代:1982

数据来源: AIP