摘要:

We present a study of the transport characteristics of electrons through abrupt GaAs–Ga1−xAlxAs–GaAs(100) double heterojunctions. The theoretical apparatus uses complex‐k‐band structures in the tight‐binding approximation and transfer matrices. States on each side of the Ga1−xAlxAs central barrier are expanded in terms of a complex‐k‐bulk state basis so as to provide a description of the wave function at the GaAs–Ga1−xAlxAs(100) interface. We treat the case where the incoming state in GaAs is derived from near the conduction band Γ point. Transmission through the Ga1−xAlxAs barrier is either tunneling or propagating depending on the nature of the Bloch states available for strong coupling in the alloy. States derived from the same extremum of the conduction band appear to couple strongly to each other across the GaAs–Ga1−xAlxAs interface. Transport characteristics of incoming states derived from near the conduction band Γ point are examined as a function of the energy of the incoming state, thickness of the Ga1−xAlxAs barrier, and alloy compositionx. Transmission through the Ga1−xAlxAs barrier is either tunneling or propagating, depending on the nature of the Bloch states available for strong coupling in the alloy.

ISSN:1071-1023    

DOI:10.1116/1.582622

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A program for solving Poisson’s equation in a single‐particle Monte Carlo simulation has been used to obtain the transverse electric field distribution in GaAs–AlxGa1−xAs layered heterostructures with an externally applied electric field parallel to the layer interfaces. The effect of transverse electric field on real space transfer in these heterostructures are described. Transverse field amplitudes are equal to or greater than threshold fields for real space transfer, and their effect on real space transfer can be significant. In general, the presence of a transverse field in a real space transfer device reduces the peak velocity and the peak‐to‐valley ratio. Also, the threshold field can either be increased or decreased by the transverse field. Saturation velocities appear to be higher if a transverse field is present, although this conclusion is somewhat tentative.

ISSN:1071-1023    

DOI:10.1116/1.582623

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

An ensemble Monte Carlo method is used to simulate electron transport through narrow high field regions which occur in planar‐doped barrier devices. These structures can achieve average velocities substantially higher than the static drift velocity corresponding to average electric field. Increased velocities in these structures arise primarily from two physical mechanisms. These mechanisms are (1) velocity overshoot and related ensemble hot electron effects, and (2) an ensemble effect due to the collecting nature of the low field/high field boundary, which is not due to hot electrons. Ballistic‐like transport can occur through narrow high field spikes. However, ballistic transport is not the major contributor to high ensemble average velocities due to scattering in regions adjacent to the high field spike. Ensemble average velocities at a given point in a device are influenced by the field distribution ahead of this point as well as that behind it.

ISSN:1071-1023    

DOI:10.1116/1.582624

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.582625

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.582626

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Recent new multilayer structures and their device applications are reviewed. These new concepts allow one to radically modify the conventional energy band diagram of apnjunction and thus tailor the high field transport properties to an unprecedented degree (band‐gap engineering). This approach has been used to propose and implement a new class of avalanche photodiodes with enhanced ionization rates ratio and the solid state analog of a photomultiplier (staircase detector). Other device applications such as repeated velocity overshoot structures are also discussed.

ISSN:1071-1023    

DOI:10.1116/1.582627

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The general field of preparation and study of metastable and modulated semiconductor structures has progressed rapidly in recent years. This short overview offers an assessment of the progress and current understanding in the areas of fabrication, characterization, and utilization of these new material system. The discussion includes the more prominent growth techniques, theoretical and experimental analysis of growth kinetics, and an overview of structural, chemical, electronic, and optical characterization. The probable application of these structures for the technological development of new device structures and concepts is considered. The discussion particularly emphasizes the prospects for future studies in view of the specific current understanding.

ISSN:1071-1023    

DOI:10.1116/1.582628

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Plasma‐assisted etching involves the interaction of radicals generated by a glow discharge (e.g., fluorine atoms) with solid material (e.g., silicon) to produce volatile products (e.g., SiF4). Moreover, this type of reaction is frequently enhanced by bombardment with ions, electrons, and photons. The purpose of the present paper is to review surface processes which lead from the adsorption of radicals to the evolution of products and to formulate a conceptual framework for the interpretation of experimental data obtained in plasma environments. It will be suggested that etching reactions are quite analogous to similar reactions which lead to oxide formation. In particular, it is suggested that field‐assisted mechanisms of the Mott–Cabrera type involving place exchange and motion of cations and/or anions are likely to influence or dominate etching reactions. In addition, it will be shown that surface reconstruction, precursor states, and the surface concentration of adsorbed species are likely to be important factors which influence the kinetics. Furthermore, emphasis will be placed on mechanisms which cause radiation (ions, electrons, photons) to enhance the reaction rate. Ion‐enhanced etching could be dominated by physical sputtering, chemical sputtering, surface damage, or a combination of these phenomena. Photon‐enhanced etching could be initiated by excitation of gas phase molecules, solid atoms or chemical species adsorbed on the surface. The characteristics of each type of reaction will be discussed with experimental illustrations.

ISSN:1071-1023    

DOI:10.1116/1.582629

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Ultrahigh molecular weight (UHMW) poly(methyl methacrylate) (PMMA) produced by plasma‐initiated polymerization was investigated for its suitability as an electron‐beam resist. Patterns exposed in this material at low to moderate doses (<5×10−6C/cm2) displayed distorted features after development in a 1:1 mixture of methyl ethyl ketone and isopropanol. The distorted features are believed to originate from a combination of pattern swelling and stress relief.

ISSN:1071-1023    

DOI:10.1116/1.582630

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Patterned silicon wafers covered with both flowed and nonflowed phosphosilicate glass films have been planarized by argon ion‐beam etching. At the optimum planarizing angle of 50°, the nonflowed PSG surface, with 1 μm high topography, is transformed to a flat surface with maximum deviations from planarity of<500 Å. The technique should alleviate resolution, linewidth control, and metallization coverage problems in very large scale integrated circuit fabrication.

ISSN:1071-1023    

DOI:10.1116/1.582631

出版商:American Vacuum Society    

年代:1983

数据来源: AIP