摘要:

The oxygen content in zone melting recrystallization silicon‐on‐insulator (ZMR SOI) layers with thicknesses ranging between 0.5 and 25 &mgr;m obtained with a movable lampheater is studied. Secondary‐ion‐mass spectrometry profiling as well as numerical calculations are presented. The simulations are based on oxygen redistribution during cooling down. In the model it is assumed that the interface reaction is fast enough to be not the rate‐limiting step in the redistribution process. Consequently, the oxygen transport was considered to be entirely diffusion limited. Good agreement was found between the measurements and calculated values. The profiles show a maximum at the center of the layer and symmetrically depleted regions in the top and bottom of the silicon film. It has been generally accepted that ZMR SOI layers have a high oxygen concentration corresponding to the saturation level at melting point. In the present study, however, we show that in the 0.5‐&mgr;m layers the oxygen concentration is as low as 1×1017(O atoms)/cm3.

ISSN:0021-8979    

DOI:10.1063/1.344520

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Cu/Ta/PtSi structures are heated between 200 and 700 °C, with Ta as a barrier for improving the thermal stability of Cu/PtSi. A small amount of Cu silicides is observed after a 30‐min anneal in N2‐H2at 300−400 °C. This is accompanied by an extensive mixing among the components present, and increasing sheet resistances. By comparing with the reactions of the Cu/Ta/Si, Al/Ta/PtSi, and Al/Ta/Si structures, the mechanisms suggested earlier are supported, with the high affinity of Cu toward Si playing a major role for the low thermal stability of the Cu/PtSi structures with and without various barrier layers.

ISSN:0021-8979    

DOI:10.1063/1.344521

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We predict thexdependencies of deep levels produced by vacancy‐impurity complexes in GaAs1−xPx. These predictions, along with those obtained earlier for thexdependencies of deep levels due to impurities, show that the slope of a deep level withxdepends strongly on the site of the impurity atom for both complexes and isolated impurities. Furthermore, we find that the slopes of some of the levels produced by the vacancy complexes are very different than those associated with the corresponding point defects. We thus suggest that the theory can be used to obtain site information about the defect producing an observed level and, in favorable cases, to distinguish between levels produced by isolated impurities and those produced by complexes. We also present photoluminescence data on two unknown centers in GaAs1−xPxand compare some of our theoretical slopes with those of the levels extracted from the data. The results show that the theory can be useful as an aid to defect identification in GaAs1−xPxx.

ISSN:0021-8979    

DOI:10.1063/1.344522

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Implantation of Si in does of 1015–1016cm−2into dry thermal oxides on silicon wafers produces a three‐state MOS memory device. For both positive‐ and negative‐going traps, gate voltage stress up to ±10 MV/cm−1generates stable (±) oxide charge near the gate and (∓) charge near the substrate. Electron paramagnetic resonance (EPR) measurement on corona‐field (≤11 MV/cm) stressed oxides revealsE’centers in regions of positive charge, which may be recycled between the EPR‐visible (+) state and the invisible neutral state. The correspondence of charge and EPR indicates a composite or Feigl‐Fowloer‐YipE’center, O33/4 Si:...+Si 3/4 O3, arising from nonstoichiometric Si fused into the SiO2lattice. Upon trapping an electron, the center rebonds to yield O33/4 SiSi 3/4 O3. The charging parameters of theE’center suggest tunneling of an electron from the (0→+) state, and are consistent with the theoretical prediction of the energy level and Franck–Condon relaxation. The three types ofE’centers observed in this and related studies are compared with theE’&agr;,E&bgr;andE’&ggr;variants of bulk amorphous silica.

ISSN:0021-8979    

DOI:10.1063/1.346059

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The behavior of the leakage current in the semi‐insulating substrate of a GaAs device is more complicated than previously recognized. The voltage dependence of this current seen in a conventional voltage‐controlled experiment has hysteresis, which arises from anS‐type negative differential conductivity (S‐NDC). This is incompatible with the conventional trap‐fill‐limited model, and we propose an alternative explanation based on the impact ionization of deep‐level traps. We show how this simple model can account qualitatively for the S‐NDC and the associated current instability, and how it can be extended when the deep traps are photoexcitable.

ISSN:0021-8979    

DOI:10.1063/1.344523

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

In this paper, we discuss and compare the rates for dominant scattering mechanisms for holes in semiconductors, including ionized impurity scattering, polar and nonpolar optical‐phonon scattering, and inelastic acoustic deformation potential scattering. The scattering rates for these mechanisms have been reviewed for the purpose of finding reliable expressions to be used in Monte Carlo simulation of hole transport inp‐type III‐V semiconductor devices. In the scarce literature on hole scattering rates, we have found several discrepancies. Here, we present corrected rates for ionized impurity scattering and for scattering by polar optical phonons. In addition, we have derived new expressions for theinelasticacoustic deformation potential scattering rates where we also have included a series expansion for the phonon occupation number, beyond the equipartition approximation.

ISSN:0021-8979    

DOI:10.1063/1.344524

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The surface voltageVof undoped amorphous silicon films has been measured as a function of the applied surface chargeQas in electrophotographic photoreceptor applications. It is found that theQ‐Vcharacteristic is nearly linear at low charge, but that the voltage saturates and eventually decreases with continued charging. This phenomenon of negative differential capacitance is explained by considering a field‐dependent carrier generation and subsequent carrier transport in an amorphous solid. It is shown that the observed results arise from the buildup of space charge when the electron and the hole &mgr;&tgr; products are sufficiently different.

ISSN:0021-8979    

DOI:10.1063/1.344525

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We investigate the effects of both carrier and phononk‐space anisotropy on the transport in bulk GaAs photoconductors. Our results show that photogeneration by laser pulses polarized perpendicular to the electric field can delay the initial velocity rise. Furthermore, anisotropic phonon amplification can degrade the turn‐off characteristics. Finally, unliken‐doped semiconductors, we find that the steady‐state velocity‐field values in photoconductors are reduced because of the nonequilibrium phonon modes.

ISSN:0021-8979    

DOI:10.1063/1.344526

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effects of energy‐band‐tail states on the recombination kinetics in heavily doped silicon have been studied by means of a Monte Carlo simulation. Three fundamental kinetic processes can be distinguished: (1) Auger recombination limited decay; (2) deep‐tail‐states emission limited decay; and (3) emission‐and‐recombination bimolecular decay. The effects of the injection level of minority carriers are investigated. Higher injection corresponds to less importance of the tail states. The relative importance of Shockley–Read–Hall recombination through the tail states is determined by the capture cross section for majority carriers and also by the lattice temperature. Results presented here will help to clarify recombination mechanisms and to extract the Auger coefficients and the band‐tail density from transient decay measurement.

ISSN:0021-8979    

DOI:10.1063/1.344527

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present results of ensemble Monte Carlo simulations of the initial femtosecond dynamics of hot‐carrier relaxation and scattering processes in bulk GaAs. Contributions of each operative scattering mechanism to the primary stage of carrier relaxation are investigated by turning them on or off separately. We find that when scattering to bothLandXvalleys is energetically possible, the initial relaxation process, which occurs on a time scale of ∼50 fs, is dominated by the intervalley scattering out of the &Ggr; valley, but cannot be described by a single, averaged scattering time. When the carriers are excited between theXandLvalleys, thermalization occurs on a time scale of ∼140 fs, which is mainly due to &Ggr;‐Lintervalley scattering, and then, optical‐phonon ande‐escatterings start to contribute in the relaxation. At low temperatures, however, optical‐phonon scattering plays only a secondary role.

ISSN:0021-8979    

DOI:10.1063/1.344528

出版商:AIP    

年代:1990

数据来源: AIP