摘要:

We report here the observation of the phonon sidebands of a bound exciton by resonant excitation of the bound exciton. By exciting fluorescence in impure samples of GaP with different laser lines one can obtain spectra in which lines associated with particular impurities show enhancement. Thus resonant fluorescence can be used as a spectroscopic tool for the study of exciton spectra in solids. We suggest this method as a possible technique for identifying unknown lines with specific impurities and as an application for tunable dye lasers.

ISSN:0021-8979    

DOI:10.1063/1.1661890

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Carriers can be injected into the oxide of a metal‐oxide‐semiconductor (MOS) capacitor by illuminating either electrode with ultraviolet light. Once injected, a voltage across the capacitor will cause the injected carriers to flow, constituting a photocurrent. The voltage dependence of this photocurrent is affected by any charge distribution which may exist in the oxide near the injecting electrode. Such oxide charge affects the photocurrent in two ways. First, the oxide charge affects the barrier position, or the distance that an electron must travel before it becomes a candidate for injection. Since the probability of a scattering eventen routeincreases with this distance, the effect of the charge on the barrier position will modify the photocurrent. Second, the oxide charge contributes to the electrostatic potential within the oxide and hence to the barrier height. Any such effect of the oxide charge on the barrier height will affect the number of electrons injected, and hence also the photocurrent. In this paper the two limiting cases when either one effect or the other dominates are examined. The minimum distance from the interface at which charge can be detected is determined for both limiting cases. It is found that this minimum distance is of the order of the scattering length of the injected carriers for the ``barrier‐position'' limit of measurement, and is limited only by the minimum absolute photocurrent detectable experimentally for the ``barrier‐height'' limit. Applying these results to the measurements of Powell and Berglund on gold‐oxide‐silicon structures we find that 90% of the so‐called ``fixed charge'' always found at the Si&sngbnd;SiO2interface cannot extend more than one scattering length (≈34 Å) into the SiO2. This result is obtained without assuming any special form for the charge distribution normal to the interface but assuming lateral uniformity parallel to the interface. Consequently, loss of sensitivity due to charge discreteness effects has not been considered. However, it is argued that such effects can be minimized by using the ``barrier‐height'' mode of measurement at low voltages. It is also suggested that lateral nonuniformities may be measurable via the dependence of the photocurrent on barrier position in the ``barrier‐height'' mode of measurement.

ISSN:0021-8979    

DOI:10.1063/1.1661891

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Powdered and single‐crystal MgO, implanted with 60 keV He, Ar, Fe, and Cr ions, have been examined by laser‐stimulated photoluminescence. The photoluminescence from damage‐related defects, centered at 14 350 cm−1, and from MgO : Cr3+zero‐phonon line at 14 325 cm−1are discussed. The annealing behavior of the introduced defects and impurities is characterized by the room‐temperature and liquid‐nitrogen‐temperature photoluminescence observed before and after 1 h anneals of 325, 600, and 900 °C. A comparison is made between the ion‐implanted and the impurity‐grown systems. Speculation is made on the nature of the damage‐related defects as the source of the broad emission centered at 14 350 cm−1. Correspondence to the previously observed absorption band at 17 420 cm−1is made.

ISSN:0021-8979    

DOI:10.1063/1.1661892

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The calculation for the compressive stress dependence of silicon diode current is refined for the⟨100⟩and⟨111⟩crystal orientations. The stress dependence of the density‐of‐states effective masses of hole bands is taken into account on the basis of Hasegawa's theory. An anomalous peak is predicted at a stress of ∼ 109dyn/cm2due to the stress dependence of the heavy hole effective masses. For the⟨111⟩orientation, a small minimum appears at a stress of ∼ 108dyn/cm2. The stress dependence of the common‐emitter transistor current gain &bgr; can be explained by the combined effects of the stress dependence of the emitter efficiency related to the above‐mentioned calculation and the stress dependence of the base transport factor. The difference of stress dependence of &bgr; betweenn‐p‐nandp‐n‐ptransistors can also be explained. It is predicted that &bgr; goes through a minimum at a stress of ∼ 109dyn/cm2. Suggestions concerning thermal stress on transistors in large‐scale integration are made.

ISSN:0021-8979    

DOI:10.1063/1.1661893

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A two‐band conduction model is used to determine the properties of shallow‐type impurity semiconductors in the presence of microwave and dc magnetic fields as a function of temperature. Measurements using cavity perturbation techniques are employed to determine the properties ofn‐type InSb and theoretical and experimental results between 4 and 300 °K are compared. The hot‐electron effect was found to be insignificant between 77 and 300 °K, and the scattering mechanisms are dominated by acoustic and polar modes over the same temperature range.

ISSN:0021-8979    

DOI:10.1063/1.1661894

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Optical measurements of the fundamental absorption edge and broad absorption tail of 50 mole% V2O5vanadium phosphate glass films were made in the range 3850–30 000 cm−1(2.6–0.33 &mgr;) before and after reducing and oxidizing anneals. The absorption in the tail region of the fundamental absorption increased during reducing anneals and decreased during oxidizing anneals. A band at 19400 cm−1(2.41 eV) was introduced by the reducing anneals. The band gapEgwas determined to be 2.71, 2.92, and 2.82 eV after successive anneals in oxygen, hydrogen, and oxygen, respectively. Evidence for direct forbidden transitions was observed from fundamental absorption edge measurements similar to that for crystalline V2O5. The concentration of reduced V4+ions is concluded to be largely responsible for the variation ofEgand of the absorption tail.

ISSN:0021-8979    

DOI:10.1063/1.1661895

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A new ferromagnetic ternary compound MnGaGe, isostructural with Mn2Sb, has been prepared by quenching from the melt and subsequent solid‐state reaction. The metallic MnGaGe is tetragonal with lattice constantsa= 3.966±0.001 Å andc= 5.885±0.001 Å. Magnetic measurements show that the Curie temperature is 185 °C and the saturation magnetization corresponds to 1.66&mgr;B/Mn atom at 4.2 °K. The easy axis of magnetization coincides with the crystallographiccaxis. The new material is thermally stable to 616 °C at which temperature it melts peritectically.

ISSN:0021-8979    

DOI:10.1063/1.1661896

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The ``elastic'' properties of lattices of reversely magnetized perfectly cylindrical domains (bubbles) are studied. Expressions are presented for the ``elastic'' constants determining the forces resulting from displacements in a general bubble lattice. Numerical results are given for the hexagonal (triangular) lattice and for various bubble spacings. ``Elastic'' wave phenomena in these lattices are investigated and the velocities of propagation are determined under the assumptions that the domain‐wall damping and the coercive field can be neglected. Finally, an estimate is made of the attenuation properties and of the quality factor of a resonating bubble lattice of finite dimensions.

ISSN:0021-8979    

DOI:10.1063/1.1661897

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The influence of an addition of Sn on the physical properties of a Fe&sngbnd;Ni Invar alloy was studied, the addition being designed to improve the mechanical properties of the Invar by precipitation hardening. Mo¨ssbauer effect with Fe57and Sn119, magnetic and dilatometric measurements, as well as hardness tests were applied. It was found that the solubility of Sn at 1130°C is at least 4.73 at.%, and 1.8 at.% at 700°C. Precipitation hardening was achieved by the formation of an intermetallic compound identified as Ni3Sn2. The hardness of the alloy increases, as does the coefficient of thermal expansion with Sn content. To counterbalance the Ni depletion of the matrix due to the formation of the intermetallic compound, a corresponding quantity of Ni has to be added. When this is done, the alloy exhibits an approximately 50% increase in hardness and an optimal coefficient of thermal expansion of 2.6 × 10−6°C−1.

ISSN:0021-8979    

DOI:10.1063/1.1661898

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

We present a thermodynamic analysis of the pyromagnetic effect for the case of a ferromagnet with uniaxial anisotropy using the molecular field approximation (MFA). We have divided the response function into a product of terms which we believe gives the best insight into the requirements of a material for a good pyromagnetic detector. In particular, we find that one should use a material with the largest magnetic heat capacity possible. Also, for small fields, we may realize the best detector withHalong the hard axis and the pickup along the easy axis. Our analysis suggests that certain of the critical point exponents, as well as the anisotropy power law behavior, may be more easily measured using the pyromagnetic technique.

ISSN:0021-8979    

DOI:10.1063/1.1661899

出版商:AIP    

年代:1973

数据来源: AIP