摘要:

Complete solid‐phase epitaxial regrowth of ion‐implanted layers in GaAs has been obtained in the temperature range 150–400 °C. Implantation of tellurium at an energy and dose slightly greater than the amorphization threshold was used to produce an amorphous layer in the near‐surface region of the GaAs samples. Complete crystallization was achieved over the entire temperature range using a resistively heated sample holder and cw laser irradiation.Insitutime‐resolved optical reflectivity measurements were used to observe and measure the epitaxial growth rate of the process. It has been found that the solid‐phase epitaxy process follows an activation law whose activation energy is 1.6 eV.

ISSN:0021-8979    

DOI:10.1063/1.335810

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Mismatch‐induced lattice strain in thin Si films grown by molecular beam epitaxy on GaP(001) substrates has been measured using transmission electron microscopy, Raman spectroscopy, and Rutherford backscattering. The perpendicular strain in the topmost part of the layers is found to be enhanced in comparison to elasticity theory. Relaxation of the strain occurs by the formation of misfit dislocations at significantly larger thickness than predicted by equilibrium theory.

ISSN:0021-8979    

DOI:10.1063/1.335811

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Thin films of Hf‐N, covering the entire composition range from pure Hf to overstoichiometric HfN, have been prepared by reactive magnetron sputtering. The structure of the films has been investigated by x‐ray diffraction, transmission electron microscopy, and scanning electron microscopy and the composition has been determined using Auger electron spectroscopy. A solubility of ≊30 at. % nitrogen is found in the &agr;‐Hf region. Above 30 at. % N a multiphase structure consisting of &agr;‐Hf, HfN, Hf3N2, and/or Hf4N3is found, which is not in agreement with the equilibrium structure. In the mononitride region a lattice parameter of ≊4.53 A˚ is observed. This value is slightly higher than reported bulk values due to intrinsic stress in the films. Increasing the nitrogen content above 50 at. % causes a distortion of the cubic symmetry of the lattice. This is first observed as an increase in the (111) interplanar spacing while other spacings decrease. Also a splitting of some reflections occurs at higher nitrogen contents. This phase transition is suggested to be due to a successive change from a cubic to a rhombohedral structure.

ISSN:0021-8979    

DOI:10.1063/1.335812

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The microhardness and electrical resistivity have been measured on thin Hf‐N films, covering the entire composition range from pure Hf to overstoichiometric HfN. Influence of substrate bias on the properties of stoichiometric HfN films has also been studied. All films have been prepared by high‐rate reactive magnetron sputtering at a substrate temperature of 400 °C. Both hardness and resistivity increase as nitrogen is added to the &agr;‐Hf phase. For the cubic HfN phase the hardness has a maximum, ≊3500 HV, and the resistivity a minimum, 225 &mgr;&OHgr; cm, at a composition close to stoichiometry. However, both values are considerably higher than those reported for bulk samples. This is explained in terms of nonequilibrium growth conditions, giving rise to high densities of dislocations and interstitially incorporated nitrogen atoms. For films with a nitrogen content above 50 at. % a very high‐resistivity value is found, 2.0 &OHgr; cm at maximum. By applying a low substrate bias voltage the resistivity of stoichiometric HfN was decreased with a factor of about 3, and simultaneously a grain growth and/or reduced defect concentration was observed. At higher bias voltages the resistivity increases and the grain sizes decrease.

ISSN:0021-8979    

DOI:10.1063/1.335813

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In a previous paper we reported the formation of the gallium‐Xcenter by neutron irradiation of gallium‐doped silicon. Since that report we have investigated a variety of other neutron‐irradiated Si:Ga samples using float‐zone crystals grown by three different vendors and irradiated at four different reactors. The behavior of Ga‐Xas a function of irradiation conditions, annealing temperatures (up to 800 °C) and various material properties has been studied by Fourier‐transform infrared absorption spectroscopy and temperature dependent Hall‐effect measurements. Ga‐Xwas not observed in any of the as‐grown samples but was definitely present in every irradiated sample. In all cases it first appears after a 400 °C anneal, reaches maximum concentration after a 600 °C anneal, and then decreases at higher anneal temperatures. The maximum Ga‐Xconcentration observed in any sample appears to be dependent on the carbon concentration in that sample and not on the irradiation conditions. A more detailed Ga‐Xabsorption spectrum was obtained showing lines not previously reported. A binding energy of 57.18±0.03 meV is deduced for the Ga‐Xground state.

ISSN:0021-8979    

DOI:10.1063/1.335814

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Microwave Hall‐effect measurements have proven invaluable for determining the Hall mobility in a wide variety of both organic and inorganic materials. Since some of these materials crystallize into needle shapes, the question of depolarization effects and the measurement and interpretation of the cavity‐scattering parameters describing the microwave Hall effect have yet to be addressed. It will be shown in this paper that the microwave Hall mobility can be found under any polarization conditions by direct measurement of the cavity input and output reflection coefficients, as well as the cavity transmission factor. Experimental results supporting this premise are presented. In addition, the sign of the microwave Hall mobility is shown to be a function of the degree of sample polarization.

ISSN:0021-8979    

DOI:10.1063/1.335815

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Experimental observation of the photovoltaic effect of a semiconductor grain boundary with a scanning laser spot is analyzed assuming a single trap energy level. The current is calculated from the recombination velocity and the concentration of the minority carriers at the grain boundary which was derived from the continuity equation. The open‐circuit voltage across the sample is obtained from equating this recombination current to the compensating current using the thermionic emission model. Using the recombination velocity and the diffusion length as variables, the calculated open‐circuit voltage is compared with the experimental data.

ISSN:0021-8979    

DOI:10.1063/1.335816

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The paper aims at the detailed analytical investigation of Raman instability in a magnetoactiven‐type cubic piezoelectric semiconducting crystal belonging to class 4¯3m under a geometrical configuration which can also be employed in analyzing the phenomenon under either Voigt or Faraday orientation. The electric vectorE0of the spatially uniform pump electromagnetic wave (applied along theyaxis) is normal to the magnetostatic fieldB0(along thezaxis) as well as to the plane of propagation (x‐zplane) of the scattered waves (&OHgr;,k) and (&OHgr;1,k1). The propagation vectorsk,k1(antiparallel to each other) are in thex‐zplane making an angle &thgr; with thexaxis. The dispersion relation has been obtained by using a hydrodynamic model of the homogeneous, piezoelectric, one‐component (electron) semiconducting plasma; and the threshold value of the pump electric field (necessary to achieve physically reasonable growth of the unstable mode) and the growth rate of the unstable Raman mode well above the threshold field have been obtained for isotropic (B0=0) and magnetoactive (B0≠0) plasmas. We have applied our analysis to a specific semiconductor,n‐InSb at 77 K, duly irradiated by a pulsed 10.6‐&mgr;m CO2laser for numerical estimation. The phase velocity of the growing unstable mode is found to be constant over the whole range of system parameters and equal to the electromagnetic wave velocity in the crystal. The magnitude of threshold electric field decreases with increasing magnetostatic field and decreasing wave vector. The growth rate increases and attains a maximum value at a certain value of the pump intensity, magnetostatic field, and &thgr;; and if these are raised further, growth rate starts decreasing. When the analysis is extended to Voigt and Faraday configurations, the results are not very encouraging.

ISSN:0021-8979    

DOI:10.1063/1.336297

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

It is shown that in some cases of the metal‐insulator‐semiconductor systems the electron tunnel current may be expressed in the form of one‐dimensional integral with modified ‘‘supply function’’ even if the effective mass is not the same in each region of the system. The proposed formula together with description of the semiconductor space charge region (which is not considered in the paper) may be used for modeling of the electron tunnel current‐voltage characteristics, e.g., of the metal–SiO2–Si⟨100⟩ tunnel diodes. The considerations are based on the electron total energy and transverse wave‐vector conservation assumptions.

ISSN:0021-8979    

DOI:10.1063/1.335817

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

High‐quality modulation doped In0.53Ga0.47As/InP heterostructures have been grown by atmospheric pressure metalorganic chemical‐vapor deposition (MOCVD) using solid trimethylindium source. The two‐dimensional nature of electrons bound in the In0.53Ga0.47As/InP heterojunctions is proved by a Shubnikov‐de Haas effect experiment. Electron Hall mobilities as high as 12000, 83000, 98000, and 92000 cm2/V s at 300, 77, 40, and 4.2 K are obtained, respectively. The electron effective mass is measured to bem@B|CR=0.043m0by cyclotron resonance experiments on the samples with two‐dimensional electron sheet concentrations of (3.0–3.7)×1011/cm2. From far‐infrared impurity absorption data the ionization energy of the residual donors in the MOCVD‐grown In0.53Ga0.47As is determined to be 2.95 meV.

ISSN:0021-8979    

DOI:10.1063/1.335818

出版商:AIP    

年代:1985

数据来源: AIP