摘要:

Pulsed (25 ns) laser‐induced heating of the &agr; phase of Mn is found to be sufficiently rapid to bypass solid‐state transformation to the high‐temperature &bgr;, &ggr;, and &dgr; allotropes and thus produce melts that are calculated to be undercooled by ∼120 K with respect to the equilibrium melting temperature of the &dgr; phase. Nucleation of the &ggr; phase in this highly undercooled melt is observed for sufficiently long melt durations. The experiments thus demonstrate that pulsed laser‐induced melting of metals with allotropes permits the study of nucleation and growth in highly undercooled melts with calculable temperatures.

ISSN:0003-6951    

DOI:10.1063/1.96544

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Simultaneous infrared transmission and laser light scattering experiments on GaAs grown by the liquid encapsulated Czochralski technique are reported. Low‐temperature photoquenching experiments are employed to demonstrate in a direct way that the nonuniform infrared images of large diameter GaAs crystals arise from absorption rather than scattering processes.

ISSN:0003-6951    

DOI:10.1063/1.96545

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Measurements of the absolute spectral density of 1/fnoise in GaAs Schottky barrier field‐effect transistors (MESFET’s) show that 1/fnoise consists of a surface component and a separable uncorrelated bulk component. The surface component is caused by trapping of electrons by surface states. The bulk component is correlated with the low field electron mobility and deep level trap concentration versus depletion depth profiles and can only be explained by the random fluctuations in the occupancy of deep level traps in the depletion region. A simple model quantitatively explains the observed characteristics of the bulk component of the noise at a low drain voltage. At normal operating drain voltages the observed 1/fnoise characteristics are consistent with the model.

ISSN:0003-6951    

DOI:10.1063/1.96546

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A heavily conducting region has been observed on implanting nitrogen into silicon for forming a buried dielectric layer. The conduction predominantly occurs in the surface silicon layer adjacent to the higher nitrogen content isolating region. The doping, ≳1018cm−3and exceeding previously observed nitrogen related doping, is relatively stable at customary 1150–1200 °C processing temperatures and its elimination requires annealing ≳1300 °C.

ISSN:0003-6951    

DOI:10.1063/1.96547

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Using video recording equipment we are able to visualize and study both the melting and freezing interfaces in lamp zone melting recrystallization of silicon on insulator (SOI) films. A so‐called ‘‘explosive’’ melting has been observed, corresponding to a noncontinuous advance of the front. We also show the effectiveness of an etched pattern in the underlying SiO2on the modulation of the solidification front. We thereby confirm the entrainment effect of this pattern. We observe then the effect of the scan speed on the liquid/solid interface morphology together with the entrainment efficiency.

ISSN:0003-6951    

DOI:10.1063/1.96548

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Atmospheric pressure metalorganic vapor phase epitaxial growth and characterization of high quality GaN on sapphire (0001) substrates are reported. Using AlN buffer layers, GaN thin films with optically flat surfaces free from cracks are successfully grown. The narrowest x‐ray rocking curve from the (0006) plane is 2.70’and from the (202¯4) plane is 1.86’. Photoluminescence spectra show strong near band edge emission. The growth condition dependence of crystalline quality is also studied.

ISSN:0003-6951    

DOI:10.1063/1.96549

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The lateral transport of dopants in silicon films on insulators during laser recrystallization is investigated. The dopants implanted locally in silicon films on insulators are found to be transported in the forward direction of the laser scan as well as the backward direction. Both transport lengths from the originally implanted region are measured as a function of the laser scan velocity. The transport mechanism is explained by taking into account a liquid phase diffusion and a segregation of impurities depending on the crystallization speed. The diffusion coefficients of (1.2±0.2)×10−4and (1.3±0.4)×10−4cm2/s for arsenic and boron, respectively, in molten silicon are obtained.

ISSN:0003-6951    

DOI:10.1063/1.96550

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Epitaxial MnSi1.7was grown locally on both (111) and (001)Si. The orientation relationships were found to be [11¯0]MnSi1.7//[111]Si, (220)MnSi1.7//(22¯0)Si and [001]MnSi1.7//[001]Si, (100)MnSi1.7//(400)Si for epitaxy grown on (111) and (001)Si samples, respectively. Three variants of epitaxy, required by the symmetry consideration, were also observed to form on (111)Si. Interfacial dislocations were identified to be of edge type with (1)/(6) ⟨112⟩ and 1/2 ⟨110⟩ Burgers vectors for epitaxial MnSi1.7grown on (111) and (001)Si, respectively. The presence of different forms of MnSi1.7is suggested in view of the important difference in details of diffraction patterns of MnSi1.7along the [001] direction. The growth of epitaxial MnSi1.7on silicon has filled the ‘‘gap’’ of the growth of stable phases of silicides of the fourth period transition elements in the periodic table epitaxially on silicon.

ISSN:0003-6951    

DOI:10.1063/1.96551

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Diodes of configuration HxWO3‖p‐ orn‐Si and HxWO3‖n‐CdS have been fabricated, where the effective work function of the HxWO3can be varied reversibly by electrochemical hydrogen insertion/extraction. The diodes have a continuously variable barrier height, as indicated by their saturation photovoltage. These systems serve as prototypes for a class of chemically sensitive electronic devices.

ISSN:0003-6951    

DOI:10.1063/1.96552

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We have studied the capacitance‐voltage (CV) and current‐voltage (IV) characteristics of molecular beam epitaxially (MBE) grownp+‐GaAs/AlAs/n‐GaAs heterostructures as a function of illumination level and temperature. Under illumination we find clear evidence of a hole inversion layer at the AlAs/n‐GaAs interface at 77 K, with a maximum inversion layer carrier concentration of about 4.1×1011cm−2. The samples are essentially free of trapping in the AlAs, as indicated by the almost complete lack of hysteresis in theCVcurves. At room temperature under steady‐state illumination we see both a voltage shift and a peak in theCVcurves. The shift is attributed to the formation of an inversion layer, while the peak is believed due to the ac response of space charge flowing through the AlAs. In contrast to recent reports on similar samples grown by metalorganic chemical vapor deposition, the MBE grown samples appear to be suitable for fabricating field‐effect devices.

ISSN:0003-6951    

DOI:10.1063/1.96553

出版商:AIP    

年代:1986

数据来源: AIP