摘要:

Collective electronic excitations within the subband structure of semiconductors with doping superlattices are discussed. We find that heterodoping superlattices with a layered electron‐hole system are good candidates for the observation of acoustic plasmons. Using the self‐consistently calculated subband structure we investigate collective electron intersubband transitions and their coupling to LO phonons.

ISSN:1071-1023    

DOI:10.1116/1.582503

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The resistance of thenchannels in GaAs doping superlattices shows clear oscillations as a function of the magnetic field, and varies with the voltage applied between thenand theplayers and with the orientation of the magnetic field with respect to the doping layer plane. These experimental results are analyzed in terms of the two‐dimensional conductivity of the system, and the subband separation is derived from a comparison between the measurements and model calculations.

ISSN:1071-1023    

DOI:10.1116/1.582504

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The growth of GaAs and III‐V alloys by MBE is now a well‐established method used to prepare a whole range of devices. One of the advantages of MBE is that the same technology can be used to study the processes controlling growth. This article will discuss the present state of knowledge concerning the growth of binary compounds such as GaAs and of alloys with mixed group III and mixed group V elements. It will also discuss the relation between growth conditions and resulting film properties for binary compounds, alloys, and interfaces.

ISSN:1071-1023    

DOI:10.1116/1.582505

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The atomic structures of crystal–vapor surfaces have been studied using Monte Carlo simulations of the Ising model and molecular dynamics simulations of a system of Lennard‐Jones particles. The roughening transition and its effects on the kinetics of growth and the crystal structure are discussed together with some implications for the growth of composition modulated crystals. Growth by two‐dimensional nucleation and an impurity mechanism are discussed. Atomic positions at close‐packed crystal–vapor surfaces are obtained from the molecular dynamics model. The atomic mobility in the surface region and the possibility of a surface melting transition are discussed.

ISSN:1071-1023    

DOI:10.1116/1.582545

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A framework for examining molecular beam epitaxial (MBE) growth of lattice‐matched III–V compound semiconductors is presented. It accounts for the basic kinetic parameters such as surface orientation and local environment dependent sticking coefficients, surface migration, and evaporation rates. Monte Carlo computer simulations are employed to examine the influence of these and other features—such as the molecular nature of the group V beam commonly employed—on the nature of the growth mechanism and the resulting interface profile. The [100] growth is found to exhibit a change from the two‐dimensional nucleation and (consequently, layer‐by‐layer) growth mechanism to a three‐dimensional nucleation mechanism with increasing growth temperature, thus exhibiting interface roughening. This interface roughening is, however, critically controlled by the surface geometry dependent surface migration kinetics. It is thus fundamentally distinct from the surface roughening transition predicted by Burton, Cabrera, and Frank which is independent of the kinetics and caused by the thermodynamic fluctuations at equilibrium. Recent studies of GaAs/AlGaAs [100]growth revealing the occurrence of interface roughening above a certain temperature, if intrinsic, we propose corresponds to the kinetically controlled surface roughening predicted by the present simulations, rather than to the surface roughening transition of Burton, Cabrera, and Frank as suggested by other investigators. The [110] growth, in the absence of exchange reactions, is found to exhibit the layer‐by‐layer growth mechanism over the commonly employed growth temperature regime. Consequently, the results predict that occurrence of rough interfaces for the [110]growth of systems such as GaAs/AlGaAs is primarily a consequence of exchange reactions induced during the deposition process. The geometry of the [110] growth front reveals such exchange reactions to be far more facile due to the expected lower activation barriers for exchange as well as for the surface migration processes of relevance. The implications of these results for understanding the [110]growth of GaAs/AlxGa1−xAs system are explored.

ISSN:1071-1023    

DOI:10.1116/1.582546

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.582547

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.582548

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Interface properties of Ge–GaAs grown by molecular beam epitaxy (MBE) have been studied using reflection high energy electron diffraction (RHEED) and high resolution cross‐sectional transmission electron microscopy (XTEM). Growth morphology studies using RHEED revealed a smooth surface for the growth of Ge on (100), (110),and (111)GaAs and for that of GaAs on (110)Ge, but indicated a rough surface on an atomic scale for the growth of GaAs on (100) and (111)Ge. The different surface morphologies observed are attributed to the formation of antiphase domains during the growth of GaAs on (100) and (111)Ge. XTEM study of a (100)Ge–GaAs superlattice showed the presence of antiphase boundaries in the GaAs layers but not in the Ge layers. The interface structures of the Ge–GaAs system are discussed based on these RHEED and XTEM results and other information obtained by channeling, Auger, and x‐ray measurements.

ISSN:1071-1023    

DOI:10.1116/1.582549

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Electron spectroscopy performed in ultrahigh vacuum can be used to measure potential and heterojunction band discontinuities at abrupt semiconductor interfaces. The technique provides a direct contactless and nondestructive means to determine and correlate interface chemistry and potential. This article discusses some of the factors which affect applications of Auger electron spectroscopy, ultraviolet photoelectron spectroscopy, soft x‐ray photoelectron spectroscopy, and x‐ray photoelectron spectroscopy for semiconductor interface potential measurements.

ISSN:1071-1023    

DOI:10.1116/1.582550

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The dielectric functions of GaAs epitaxial layers have been measured at various temperatures and doping levels in a growth chamber using a spectroscopic ellipsometer. The 3 eV region is found to be especially sensitive to defects and dopants. The experimental dielectric functions can be described by a collection of seven harmonic oscillators with adjustable peak position, width, and height. Using the same set of oscillators with simple variations of the parameters, the dielectric function of AlxGa1−xAs ternaries of any composition can be obtained. These reference data have been used to investigate the chemical and structural nature of GaAs/Al0.54Ga0.46As and Al0.54Ga0.46As/GaAs heterojunctions fabricated in a MOVPE reactor. Interface regions are determined to be respectively, a 15±9Å thick chemical mixture and a nonexistent (0±5 Å) interface. These results upon the relative quality of the two types of heterojunctions are consistent with electrical measurements.

ISSN:1071-1023    

DOI:10.1116/1.582551

出版商:American Vacuum Society    

年代:1983

数据来源: AIP