摘要:

The deep level transient spectroscopy (DLTS) technique has been used to study changes in electron trapping centers as a function of substrate growth temperature (550 °C≲Tsub≲675 °C) inn‐Al0.25Ga0.75As Schottky barriers grown by molecular beam epitaxy (MBE). The principal result is a deep level atEc−0.78 eV which decreases by over an order of magnitude in concentration as the growth temperature is increased from 575 to 675 °C.

ISSN:0021-8979    

DOI:10.1063/1.328516

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The bias field dependence of the velocity of bubble propagation by the domain drag effect was studied in a GdCoAu amorphous film. Bubbles in close‐packed arrays were propagated by pulsing currents directly through a stripline of the material fabricated by photolithography and ion‐beam milling. As bias field is increased, at given current and pulse width, the velocity decreases, passes through a minimum, then increases again. The domain drag drive field at a given bias is derived both from the critical current at which motion begins and from the slope of velocity with current. A theory for the domain drag drive fieldHdof a bubble raft with infinite length along the current direction is derived, giving the simple resultHd/&bgr;jD= 1/2(d0/D) −(&pgr;/4&sqrt;3)(d0/D)3, where &bgr; is the Hall angle,jis the current density,d0is the bubble diameter, andDis the nearest‐neighbor spacing. Experimental results from critical current agree approximately with the theory, but results from velocity slope with current are a factor of 3 too high.

ISSN:0021-8979    

DOI:10.1063/1.328517

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Silicon wafers implanted with arsenic doses from 1×1015to 2×1016As/cm2were characterized with the following methods: four point probe, bevel and stain, secondary ion mass spectroscopy, spreading resistance, incremental sheet resistance, and infrared transmittance and reflectance. The results are compared and the capability of each method is discussed.

ISSN:0021-8979    

DOI:10.1063/1.328518

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Weak‐field galvanomagnetic measurements were carried out at room temperature on a (001)‐circular flat sample of ann‐type Ge single crystal using the Van der Pauw‐Wasscher technique, with the magnetic field parallel and normal to the sample plane. Thus, the anisotropy which appears in the (001)‐plane of cubic crystals due to the magnetic field is investigated and the existence of the magnetoresistance skewness effect is established experimentally. This effect allows the determination of all the galvanomagnetic coefficients in a simple way. The new result concerning Ge is the negative sign of the &rgr;1212coefficient which is attributed to the reverse rotation of the magnetoresistance.

ISSN:0021-8979    

DOI:10.1063/1.328519

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Weak‐field magnetoresistance measurements at 297 K were used in conjunction with an appropriate band structure model to detect the substrate‐induced strain inn‐type PbTe epitaxial films grown on BaF2. Evidence of strain in as‐grown films was found. The temperature of the sample was repeatedly cycled from 297 to 4.2 K and back, and the 297‐K strain was found to decrease. At the same time, Hall effect and resistivity measurements show that the 4.2‐K mobility dropped and the 297‐ and 4.2‐K carrier concentrations increased. The observed effects are ascribed to an extended defect density which grows larger as the number of thermal cycles increases.

ISSN:0021-8979    

DOI:10.1063/1.328556

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Transient response of In/x phase of metal‐free phthalocyanine Schottky barrier photovoltaic cells as a function of the applied reverse bias has been investigated under pulse and step illumination conditions. In both cases the dependence of the photoresponse on the applied bias showed the change in shape when the light wavelength was changed. This can be interpreted in the framework of the local carrier generation model in which it is assumed that the carrier generation is dominated by the contribution from the barrier region. In the constant illumination mode, it was clearly demonstrated that the photocurrent has two components—the true photocurrent component and the component caused by changes in the barrier properties. For the true photocurrent component, using strongly absorbed red light for illumination, a saturation was observed which enabled the determination of quantum efficiency of carrier generation in the barrier of 70%.

ISSN:0021-8979    

DOI:10.1063/1.328557

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A method for determining quantum efficiencies of carrier generation of photoconductive particles dispersed in inert polymer matrices is proposed. It has been applied to study generation efficiencies in x phase of x‐metal‐free phthalocyanine dispersed in a polystyrenen‐butylmethacrylate copolymer matrix. Data for pigment concentration from 1% to 20% by weight give consistent values for the generation efficiencies, confirming the value of the proposed method.

ISSN:0021-8979    

DOI:10.1063/1.328558

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We report the results of a systematic study of correlations in the collection efficiency, collection length, depletion width, midgap density of states and energy‐band gap in sputter and silane‐decomposition‐produced amorphous hydrogenated silicon Schottky diodes. Films produced by sputtering have a collection lengthLc, which is less than the depletion widthW, unlike silane‐decomposition‐produced films for whichLc≃W. We show that the relatively weak variation of the deduced hole‐mobility‐lifetime product with midgap state density and temperature is consistent with the holes becoming immobilized before recombining. The collection efficiency is found to be controlled dominantly by the field‐assisted diffusion of carriers in the depletion region, and not limited by geminate recombination.

ISSN:0021-8979    

DOI:10.1063/1.328559

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

n+/pandp+/n/n+solar cells were fabricated by using ion implantation and pulsed laser annealing. With these techniques it is possible to obtain emitters which are doped well beyond the solubility limit and present lower sheet resistivities for equal junction depth. The dopants used were phosphorus, arsenic, and boron, and the implanted doses ranged from 2×1015at/cm2up to 5×1016at/cm2. Measurements of diffusion length, quantum efficiency, and reflectivity enabled us to demonstrate that the supersaturated layers are characterized by high values of the absorption coefficient, which determines a poor short‐circuit current and consequently a low conversion efficiency. This effect seems to be very marked for concentrations higher than 1021at/cm3. Also, the reflectivity depends on the surface doping, showing a considerable decrease for the highest concentrations examined.

ISSN:0021-8979    

DOI:10.1063/1.328560

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Deep traps in amorphous selenium are measured using a thermally stimulated current (TSC) technique. A peak is found in the TSC curve, which arises from the thermal liberation of trapped carriers in the bulk of amorphous selenium. It is found that the trapped carriers are mainly positive holes in the temperature range 170∼310 °K. Three methods (Grossweiner’s method, initial rise plot method, and varying temperature rising rate method) are applied to obtain the trap activation energy. It is concluded that the trap activation energies are distributed from 0.6 to 1.1 eV.

ISSN:0021-8979    

DOI:10.1063/1.328561

出版商:AIP    

年代:1981

数据来源: AIP