摘要:

Penetration results are reported for four low strength materials attacked by a non‐precision, copper‐shaped charge jet. The materials are methanol, Plexiglas, glycerol, and mild steel. The results are not entirely consistent with the recent compressibility‐based predictions by B. S. Haugstad and O. S. Dullum [J. Appl. Phys. 52, 5066 (1981)] and by N. A. Zlatin and A. A. Kozhushko [Combust. Explos. Shock Waves USSR 16, 559 (1980)]. Methanol and Plexiglas have extraordinary penetration resistance due to a combination of shock wave formation, plastic flow resistance, vaporization, and decomposition. The more chemically stable glycerol has simpler behavior that is similar to mild steel.

ISSN:0021-8979    

DOI:10.1063/1.331192

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Lightly dopedp‐type GaAs films grown by molecular beam epitaxy on Cr‐doped substrates have been chemically analyzed using dynamic secondary ion mass spectrometry. Residual levels of Cr are, in general, below 4×1013cm−3. A major source of impurities in such material is identified. The effect of substrate temperataure on the concentration of B, Mg, Al, Si, Ca, Cr, Mn, Fe, and Cu are reported, and their likely effect upon the minority carier properties of the layers is discussed.

ISSN:0021-8979    

DOI:10.1063/1.331193

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Aluminum Schottky barrier heights (&fgr;n) to GaAs depend heavily upon the deposition conditions and the gallium arsenide surface stoichiometry. After annealing to approximately 320 °C diodes show &fgr;bapproximately 0.69 eV in association with oxygen at the Al/GaAs interface. We infer that these ’’stabilized’’ barrier heights are associated with oxygen‐induced surface‐state pinning of the GaAs Fermi level. Al deposition on arsenic stabilized surfaces show variable barrier heights and no oxygen peak indicating variable Al induced states in intermediate AlGaAs layers between the Al and GaAs.

ISSN:0021-8979    

DOI:10.1063/1.331194

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Ion dechanneling and sputter‐auger spectroscopy have shown the composition of molecular‐beam epitaxial ternary group III arsenide alloys to depend upon the growth temperature in a manner consistent with preferential congruent desorption of the more volatile group III element.

ISSN:0021-8979    

DOI:10.1063/1.331195

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The effect of parabolic and nonparabolic band structures on the propagation of ultrasound at an angle &Vthgr; relative to the direction of a dc magnetic field B in a degenerate semiconductor such asn‐type InSb is investigated by using a quantum treatment which is valid at high frequencies and in strong magnetic fields. Numerical results show that the absorption coefficient and change in sound velocity depend strongly on the direction of the propagation of ultrasound relative to the magnetic field for both parabolic and nonparabolic band structures. However, the absorption coefficient and change in sound velocity for the nonparabolic band structure will diminish and become small in the intermediate‐magnetic‐field region when the angle &Vthgr; is larger than 30°.

ISSN:0021-8979    

DOI:10.1063/1.331196

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The spectral response of Schottky diodes on hydrogenated amorphous silicon has been determined between 1 and 3.5 eV. An anomalous absorption peak clearly appears at low energy from these experiments. We have demonstrated that this peak is due to optical transitions from localized states near the valence band to the conduction band, and is connected with hole trapping during the transport.

ISSN:0021-8979    

DOI:10.1063/1.331197

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

This paper presents a theoretical investigation of the filamentation instability of high power helicon waves in magnetoactive semiconductors. Fluid equations have been used to find the nonlinear response of the low‐frequency electrostatic space‐charge density perturbation in a semiconductor. The low‐frequency nonlinearity arises through the ponderomotive force on electrons, whereas the high‐frequency nonlinearity arises through the equation of continuity. For typical parameters inn‐InSb: &egr;L= 16 at 77 °K,n00?2×1014/cm3,Bs?0.8 kG, &ngr;0= 5×1010rad/sec, &ohgr;0= 1010rad/sec, and for the power density of the incident helicon beam ?30.27 KW/cm2, the growth rate of the instability turns out to be ∼1.71×106rad/sec.

ISSN:0021-8979    

DOI:10.1063/1.331198

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The photoconductivity of epitaxialn‐GaAs (n= 2.6×1014cm−3) has been measured in response to high intensity (P∼2.4 kW/cm2) radiation at &lgr; = 95 &mgr;m. The saturation curve of photoconductivity versus excitation power yields a recombination time of 10−8s, which is much shorter than the value predicted, 10−6s, by the theory of the electron‐phonon interaction. Recombination appears to occur from localized states as well as by capture of free conduction band electrons.

ISSN:0021-8979    

DOI:10.1063/1.331199

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The temperature dependence, over the 4.2–100 K range, of the narrow EPR line, labeledX, with an isotropic value ofg= 2.002 has been investigated in a semi‐insulating GaAs:Cr sample. From its Curie‐Weiss behavior, leading to a (T+13.1)−1law, it is concluded that it may result from antiferromagnetic exchange coupled spins, originating from dangling bonds located on extended defects present in the crystal.

ISSN:0021-8979    

DOI:10.1063/1.331200

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The effect of nonuniformity of the insulating layer on metal‐insulator‐semiconductor, open‐circuit voltage is examined. It is based on a simplified model in which insulator limits the dark current via different effects. The enhancement inVoccould be greatly degraded by surface roughness.

ISSN:0021-8979    

DOI:10.1063/1.331201

出版商:AIP    

年代:1982

数据来源: AIP