摘要:

The results of an investigation of the effects of temperature, during both theinsituargon sputter clean and the deposition, on the electrical properties of low‐temperature (Tdep≤800 °C) expitaxial silicon films are presented. The data indicate that the electrical quality does not depend on the sputter temperature, at least for temperatures in the 750–800 °C temperature range. The electrical quality is a strong function of the deposition temperature, however. Epitaxial layers deposited at 800 °C have electrical characteristics comparable or superior to bulk silicon. However, reducing the deposition temperature to 750 °C results in a significant degradation in the film electrical properties. The electrical quality is stable to further annealing for temperatures in the 750–950 °C range. The mechanism responsible for the dependence of the film electrical quality on the deposition temperature is described.

ISSN:0021-8979    

DOI:10.1063/1.340248

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The results of an investigation of the effects of varying the deposition rate on the surface morphology and electrical characteristics of low‐temperature (Tdep=775 °C) epitaxial silicon are presented. The data indicate that the electrical characteristics are a strong function of the growth rate, even more so than the deposition temperature. Varying the growth rate by a factor of 16 varies the minority‐carrier lifetime and reverse‐bias diode leakage current by five orders of magnitude, and has a strong impact on the surface morphology of the epitaxial layer. Deposition conditions will be reported that yielded a minority‐carrier lifetime of 480 &mgr;s, which is the highest lifetime reported in low‐temperature epitaxial silicon.

ISSN:0021-8979    

DOI:10.1063/1.340249

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Silicon vapor‐phase epitaxial growth with SiH2Cl2is theoretically studied. The optimized geometries and total energies of the species, generated from SiH2Cl2, are calculated by using anabinitiomolecular orbital method. The charge transfer of the interaction between a silicon surface and SiCl2is considered. Based on the computational result that SiCl−2has the lower total energy that SiCl2, a new adsorption mechanism, named charge transfer adsorption, is proposed. By using this charge transfer adsorption followed by the surface reaction at the hollow bridge site, the epitaxial growths on the silicon (001), (111), and (110) surfaces are discussed. The epitaxial growths take place in different ways for these three surfaces because of the specific locations of the hollow bridge sites.

ISSN:0021-8979    

DOI:10.1063/1.340250

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Sulphur from an electrochemical source has been used to dope GaSb grown by molecular‐beam epitaxy. The incorporation of sulphur in the epilayers has been measured by secondary ion mass spectrometry, and the effects of substrate temperature during growth and of the antimony‐to‐gallium flux ratio have been studied.The incorporation has been found to be a strong function of substrate temperature, varying from ∼100% below 435 °C to ∼1% at 525 °C. The incorporation also increases with antimony overpressure, varying by a factor of 3 on changing the antimony‐to‐gallium flux ratio from 1:1 to 4:1. The substrate temperature dependence is described by a simple kinetic model. The electrical activity of the incorporated sulphur is shown to be close to 100%.

ISSN:0021-8979    

DOI:10.1063/1.340251

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

We present a complete investigation of crystalline, optical, and electrical properties of molecular‐beam‐epitaxial‐grown AlGaInAs lattice matched to InP covering the whole range of concentrations. Using the two indium cells method, we show very easy control of lattice matching of this quaternary system which can be written as (Al0.48In0.52As)z(Ga0.47In0.53As)1−z. X‐ray double diffraction profiles do not depend on the Al concentration and they show sharp diffraction linewidth. The PL full widths at half maximum are comparable to the narrowest reported. Transmission electron microscopy shows excellent crystallinity forzup to 0.60. Room‐temperature electron mobility higher than 4000 cm2/V s forzup to 0.40 is comparable to that of InP and is the best result reported up to now for these quaternary alloys. This system is thus quite suitable for microwave and optical devices applications.

ISSN:0021-8979    

DOI:10.1063/1.340252

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

GaAs surface cleaning by thermal oxidation and sublimation prior to molecular‐beam‐epitaxial growth has been investigated as a means of reducing the carrier depletion at the substrate and epitaxial layer interface. The carrier depletion between the substrate and epitaxial films, measured by aC‐Vcarrier profiling technique, was shown to decrease significantly with an increase in the thickness of the thermal oxidation. The concentration of carbon contamination near the substrate‐epitaxial interface was measured using secondary ion mass spectroscopy. The carbon concentration correlated very well with the carrier depletion. Therefore, the main origin of the carrier depletion is believed to be the carbon concentration of the initial growth surface. Based on these results, the thermal oxidation and sublimation of a semi‐insulating GaAs substrate was successfully applied to improve the mobility and sheet concentration of the two‐dimensional electron gas in selectively doped GaAs/N‐Al0.3Ga0.7As heterostructures with very thin GaAs buffer layers.

ISSN:0021-8979    

DOI:10.1063/1.340253

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Polycrystalline films of CdTe (with grain size up to 100 &mgr;m) were grown by the hot wall close‐spaced vapor transport technique in an Ar atmosphere. In most cases they grow on a zinc‐blende type of structure with a preferential orientation of growth along the ⟨111⟩ directions, as shown by x‐ray diffraction studies. The grain size in the films presents a maximum around 3.5 Torr, as well as a minimum of preferential orientation. The grain size shows an exponential increase in the substrate temperature (Ts) 450–650 °C range. ForTs≤600 °C, the films grow with a ⟨111⟩ preferential crystallographic orientation, whereas forTs>600 °C the preferential orientation changes to the ⟨220⟩ directions. ForTs>600 °C, the films show a mixture of zinc‐blende and wurtzite phases, according to the x‐ray analysis. A Te crystalline phase is detected forTs>550 °C.

ISSN:0021-8979    

DOI:10.1063/1.340254

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Rapid thermal annealing (RTA) using halogen lamps for Si‐implanted (250‐keV, 2×1013cm−2dose) semi‐insulating liquid‐encapsulated Czochralski GaAs has been investigated by deep level transient spectroscopy. RTA has been performed at 700, 800 and 900 °C for 6 s with SiO2encapsulation. For comparison, conventional furnace annealing (FA) has also been performed at 800 °C for 20 min. In the RTA samples at 700 °C, three electron traps NI1 (Ec−0.53 eV), NI4 (Ec−0.63 eV), and EL2 (Ec−0.78 eV) are observed on the Cr‐doped substrate, while the traps NI1, EL2, and NI3 (Ec−0.47 eV) are observed on the undoped substrate. In RTA samples above 800 °C, the electron trap NI2 (Ec−0.55 eV) or EL2 is dominant and traps NI1, NI3, and NI4 are not detected. It is possible that three traps NI1, NI3, and NI4 are residual defects produced by Si implantation. The low concentration of the trap EL2 in FA samples is due to the out‐diffusion of it. This phenomenon can be related with the change of the stoichiometry in the implanted layer by the formation of the transition region at the SiO2/GaAs interface during FA. The notable spatial variation of the trap NI2 is observed across the wafer. On the other hand, the peculiar spatial distribution of the trap EL2 is not observed across the RTA sample. Furthermore, the trap EL2 concentration does not depend on RTA temperatures. It is possible that the spatial distribution of the trap EL2 across the RTA sample is changed by Si implantation and RTA.

ISSN:0021-8979    

DOI:10.1063/1.340255

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The existence of long‐range potential fluctuations (PF) in compensated semiconductors results from the nonuniform distribution of ionized impurities, and it was observed that PF can be erased when the material is submitted to a critical field, the value of which depends on the sample. Data on the temperature and time dependence of the discharge current of a semi‐insulating GaAs crystal, which has been submitted to a critical field, are reported. The discharge current decreases with a time constant equal to the reverse of the electron emission coefficient of deep centers brought out of equilibrium by the external field. Not only the activation energy of the emission coefficient, but also the density of the deep center species responsible for the discharge current, can be determined from the data. In the case of the GaAs sample studied in this paper, the observed discharge current results from the return to equilibrium of the Cr acceptor center HL1.

ISSN:0021-8979    

DOI:10.1063/1.340256

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The band‐gap narrowing in heavily doped silicon has been studied by optical techniques—namely, photoluminescence and photoluminescence excitation spectroscopy—and by electrical measurements on bipolar transistors. The optical experiments give a consistent set of data for the band‐gap narrowing inn‐ andp‐type material at low temperatures as well as at room temperature. A good agreement is found between the optical and electrical data removing the discrepancies existing so far in the literature.

ISSN:0021-8979    

DOI:10.1063/1.340257

出版商:AIP    

年代:1988

数据来源: AIP