摘要:

We report a Monte Carlo study of hole transport in AlxGa1−xAs, In1−xAlxAs, and GaAsxSb1−x. The effects of alloy scattering are significant in all three cases, but mobilities are still high enough to be advantageous in particular device applications. We separately calculate the Hallrfactors by a Boltzmann transport method and show that these factors are vitally important when attempting to compare Monte Carlo drift mobilities with experimental Hall data. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359052

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present analytical expressions for the differential‐mobility spectra which are obtained from a linear analysis of the balance equations under stationary and homogeneous conditions. The expressions are rigorously related to an eigenvalue expansion of the response matrix and are applicable to ohmic as well as to non‐ohmic conditions. The coefficients appearing in the formula can be calculated from the knowledge of three parameters as functions of the electric field, namely, the reciprocal effective mass, the drift velocity, and the average energy of the carriers. The theory is applied to the case of holes in Si atT=300 K and validated by comparison with the results obtained by a direct numerical resolution of the perturbed Boltzmann equation. ©1995 American Institute of Physics. 

ISSN:0021-8979    

DOI:10.1063/1.359053

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Strain‐relaxed Ge0.3Si0.7/Si, grown by rapid thermal chemical‐vapor deposition, has been investigated with deep‐level transient spectroscopy (DLTS) and bias‐dependent electron‐beam‐induced current (EBIC). A single electron trap and several hole traps have been detected in these samples. The apparent electron capture cross section is found to be ∼2×10−13cm2, which is several orders of magnitude larger than the apparent hole capture cross sections (∼10−17cm2), and is responsible for the detection of the minority‐carrier electron trap even under reverse‐bias majority‐carrier capture conditions. All observed traps which were investigated as a function of filling pulse time exhibit logarithmic capture kinetics, as expected for extended defects, and the bias‐dependent DLTS peak height and EBIC relative defect contrast are consistent with the spatially varying dislocation density. Moreover, the trap concentration, as determined by DLTS, is correlated to the dislocation density, as determined by EBIC measurements. Based on a comparison of Arrhenius plots, the observed logarithmic capture kinetics, the correlation of trap density to dislocation density, and the observed bias dependence, the electron trap appears to be related to dislocation core states, while two of the hole traps appear to be related to either dislocation core states or Cottrell atmospheres. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359054

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Properties of Ga2O3thin films deposited by electron‐beam evaporation from a high‐purity single‐crystal Gd3Ga5O12source are reported. As‐deposited Ga2O3films are amorphous, stoichiometric, and homogeneous. Excellent uniformity in thickness and refractive index was obtained over a 2 in. wafer. The films maintain their integrity during annealing up to 800 and 1200 °C on GaAs and Si substrates, respectively. Optical properties including refractive index (n=1.84–1.88 at 980 nm wavelength) and band gap (4.4 eV) are close or identical, respectively, to Ga2O3bulk properties. Reflectivities as low as 10−5for Ga2O3/GaAs structures and a small absorption coefficient (≊100 cm−1at 980 nm) were measured. Dielectric properties include a static dielectric constant between 9.9 and 10.2, which is identical to bulk Ga2O3, and electric breakdown fields up to 3.6 MV/cm. The Ga2O3/GaAs interface demonstrated a significantly higher photoluminescence intensity and thus a lower surface recombination velocity as compared to Al2O3/GaAs structures. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359055

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Light‐emitting diodes (LEDs) of poly(2‐methoxy‐5‐(2’‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene) were fabricated using high surface area hole‐injecting network electrodes madeinsitufrom blends of polyaniline (PANI) in low molecular weight polyester resin. Due to the high interface area between the PANI network and the active luminescent layer and enhancement of the local electric field at the rough surface of the PANI network, charge carrier injection was significantly improved. LEDs using the PANI network electrode have lower device operating voltage, higher quantum efficiency, and significantly increased brightness. Polymer LEDs fabricated with the PANI‐CSA network as anode and aluminum:lithium alloy (0.2% Li) as the cathode turn on at 1.7 V, and achieve a brightness in excess of 400 cd/m2at 3 V with a measured external quantum efficiency of 2.23% photons/electron. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359056

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electron spin resonance spectroscopy is used to study the effects of thermal NH3nitridation and subsequent reoxidation on the structure of the dielectric/silicon interface. This is accomplished by study of thePbcenter, an interfacial point defect. The values ofg⊥inPbspectra observed in the nitrided oxide and reoxidized nitrided oxide systems differ from Si/SiO2systems, suggesting that the average value of the tensile stress in the silicon substrate increases upon nitridation while reoxidation acts to return the interfacial stress to prenitridation levels. The implications of these structural changes upon device performance are discussed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359057

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The intrinsic mechanism of the generation of subpicosecond electrical pulses by nonuniform illumination of GaAs transmission‐line gaps is investigated using a self‐consistent Monte Carlo approach. It is attributed to the photocarrier‐induced field redistribution, which results in a displacement current pulse that is independent of the carrier lifetime. Partial‐gap illumination and high dark resistivity are the prerequisites for this pulse generation technique. The pulse dependence on light intensity, excitation wavelength, bias voltage, and the asymmetric response to bias polarity are discussed and clarified. It is predicted that this mechanism should also be observable in other semiconductors such as silicon. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358991

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Microcrystalline silicon (&mgr;c‐Si:H) layers deposited by the very high‐frequency‐glow discharge technique at a radio‐frequency excitation of 70 MHz are observed to be basically slightly ⟨n⟩ type. By doping (so‐called ‘‘microdoping’’) with boron in the gas phase volume part per million (vppm) range, compensated material could be obtained. The influence of this doping on the electronic transport properties is documented. A pronounced onset of the boron incorporation into the films measured by secondary‐ion‐mass spectrometry is observed around 3 vppm (B2H6/SiH4), together with marked changes in the electrical properties. The compensated film obtained for a microdoping of about 1 vppm shows the lowest dark conductivity [3×10−8(&OHgr; cm)−1], the highest activation energy (517 meV), and, finally, the highest photoconductive gain of 6×103(photo/dark current ratio). Depending on the value of the activation energy (the critical value is ≊0.2 eV), two different transport models are identified, corresponding to ‘‘Meyer–Neldel’’ or ‘‘anti‐Meyer–Neldel’’ behavior. As for light‐induced degradation, the compensated film exhibits better stability than undoped films. Finally, the use of slightly boron doped &mgr;c‐Si:H as photovoltaically active material will be discussed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358992

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The electrostatic potential and the carrier distribution in periodically line‐doped structures are calculated within the semiclassical approximation. When the distance between the doped lines is 8 nm, which is a typical periodicity experimentally realized on the (100) GaAs surface, the system is regarded as a lateral superlattice instead of parallel wires because of strong overlap of the electron charge. Moreover, the modulation is anticipated not to be sufficient to probe the electronic state unambiguously. Alternative possible structures to enhance the modulation, which may provide more suitable systems for experiments, are investigated. It is shown that the confinement is stronger for heavier carriers by virtue of their smaller screening length. The coupling among the wires is suppressed by inserting weakp‐type dopant lines in between the channels. An application of the line doping to a heterojunction is also examined. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359517

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A study has been made of the xerographic properties of amorphous selenium doped with chlorine at concentrations below 100 parts per million (ppm) by weight. The sample consisted, in each case, of an aluminum plate with a thin deposited rf sputtered aluminum oxide film, on which a 50 &mgr;m layer of amorphous selenium was deposited by evaporation, at a substrate temperature of 50 °C. It was found that the chlorine decreased the acceptance voltage following corona charging, increased the dark decay rate, and decreased the residual voltage after illumination discharge. The changes were such as to be beneficial xerographically for small additions of chlorine to the selenium in the ppm range. Analysis of the time derivative of the dark decay voltage indicated that depletion discharge was the dominant process in the decrease of dark decay voltage with time and a modified relation was introduced to describe the increase of bulk space‐charge density with time, arising from thermal excitation of holes from deep discrete centers in the photoreceptor. This analysis indicated a decrease of the release time of the holes with increase of chlorine content, whereas an observed decrease of single cycle and cycled‐up residual voltages with increased chlorine indicated an increase of hole capture time from their relevant trapping centers. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.358993

出版商:AIP    

年代:1995

数据来源: AIP