摘要:

The valence‐band structure of unstrained In0.27Ga0.73As grown as a 4000‐Å‐thick overlayer on GaAs, has been determined in the (001) direction from angle‐resolved photoemission data. The InGaAs bands lie between the bands of InAs and GaAs but the differences depend onk. The potential in the alloy is therefore not a simple average of that of the constituent compounds.

ISSN:0734-2101    

DOI:10.1116/1.575791

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Different experimental factors which influence the determination of oxygen content in AlxGa1−xAs semiconductor layers by secondary ion mass spectroscopy (SIMS) are described. The technique used involves flooding the sample surface with18O during profiling and corrects for errors due to oxygen adsorption on the sample surface during the analysis. Quantitative values for16O content are obtained by comparison with implanted standards, taking into account corrections for changes in Al content and/or erosion rate. Simple tests allowing to check the analysis for charging effects and for internal consistency are illustrated. The results show that O concentrations down to the 4×1017cm−3level can be reliably determined.

ISSN:0734-2101    

DOI:10.1116/1.575792

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Quantitative measurements of oxygen content in epitaxial AlGaAs layers grown by molecular‐beam epitaxy (MBE) are presented and compared with results on liquid phase (LPE) and metalorganic vapor phase epitaxy (MOVPE) layers. The analysis of oxygen concentration profiles measured on GaAs/AlGaAs or GaAs/AlAs multilayers shows that the oxygen incorporation in AlxGa1−xAs layers is arrival rate limited with a sticking coefficient essentially equal to one. The incorporation appears to proceed by a surface exchange reaction via an intermediate O‐containing floating boundary layer. This interpretation is consistent with the experimental observations that the oxygen content of the MBE layers is independent of growth temperature between 600 and 700 °C, and that the oxygen level goes through a sharp maximum at the interface between a high Al and low Al content layers due to surface accumulation effects. Oxygen levels are found to be lower by a factor of 2 to 3 in multiquantum well (MQW) compared to random alloy layers of the same average Al content. Lowest16O levels measured in ternary AlxGa1−xAs layers with 0.3

ISSN:0734-2101    

DOI:10.1116/1.575793

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The background sources have been studied in the trace analysis of carbon (and oxygen) using secondary ion mass spectrometry. In particular, the physical mechanism limiting the detection limit of carbon (and oxygen) in GaAs was investigated. It was speculated that the three kinds of background sources could be discriminated using the simple method that we called the background source analysis (BGA) method. It was found that memory effect was the most harmful barrier to lowering the detection limit of carbon impurity in GaAs at the conventional pressure (10−9Torr). On the basis of the quantitative BGA method, the best condition of the measurement in the trace analysis of carbon in GaAs was estimated to be 50 nA for the primary beam current at the raster‐scanned area of 30×30 μm2.

ISSN:0734-2101    

DOI:10.1116/1.575794

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Intensity profiles along the specular streak of the reflection high‐energy electron diffraction (RHEED) pattern observed during GaAs growth by molecular‐beam epitaxy (MBE) show intensity peaks from diffuse scattering processes as well as the specular intensity peak. Intensity oscillations from the diffuse scattering peaks vary in phase with the intensity oscillation at the specular position, with the phase variation depending on the incident angle of the electron beam. Calculation of major Kikuchi line escape angles near the [110] azimuth shows that the diffuse scattering peaks observed are at Kikuchi angles. At some incident angles, interference between Kikuchi and specular scattering is found to change the phase of the oscillation observed at the specular position, as reported by other workers. Interference from Kikuchi processes should be more easily avoided when observing along an azimuth a few degrees off of the [110]direction than when observing directly along the [110] direction. Oscillation phase versus escape angle measurements along an azimuth 7° off [110]show that the phase versus angle curve is somewhat less erratic than that measured directly along the [110] direction by other workers. We still find, however, that the oscillation phase observed at the specular position is shifted over much of the angular range, complicating the common interpretation in which RHEED oscillation maxima correspond to the smoothest growth surfaces.

ISSN:0734-2101    

DOI:10.1116/1.575795

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

A remote plasma metalorganic chemical vapor deposition (CVD) system was designed, constructed, and characterized mathematically and experimentally. The system uses a new unique reactor geometry which is particularly well suited to remote plasma CVD. GaAs was grown in the system with and without a rf plasma and the results compared for various electrode geometries. The plasma reduced the activation energy for growth from 18 kcal/mol without plasma to 14 kcal/mol with plasma and increased the growth rate by as much as two orders of magnitude between the temperatures of 500 and 600 °C. The rf electrode geometry and the distance between the plasma and the wafer were the most critical parameters in determining the growth rate with plasma.

ISSN:0734-2101    

DOI:10.1116/1.575796

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Theoretical and experimental results are presented to shed light on the atomistic nature of Hg incorporation during HgCdTe growth. The extremely large difference in the bond strengths of the Cd–Te and Hg–Te forces the choice of growth conditions where Hg incorporation is extremely small and controlled essentially by two key factors: (i) Te2overpressure and (ii) kink site density at the growing surface. While the role of Te2overpressure was explored earlier, the role of the second factor will be the subject of this paper. The kink site density is in general time dependent during growth; it can also be varied by choosing different growth directions. Consequently, the Hg incorporation rate, which is closely tied to surface kink site density, is altered. These issues and their importance on HgCdTe alloys and HgCdTe–CdTe heterostructures are explored.

ISSN:0734-2101    

DOI:10.1116/1.575797

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

It was previously found thatn‐type Hg(1−x)CdxTe with 0.7

ISSN:0734-2101    

DOI:10.1116/1.575798

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The buildup of damage induced by In ion implantation into Hg1−xCdxTe for various composition (x=0,x=0.24,x=0.4,x=0.7, andx=1) was measured by means of channeling Rutherford backscattering spectroscopy (RBS). Damage profiles were extracted from the spectra using a model based on Quere’s dechanneling treatment. Despite the large difference in bond nature and the related physical properties between the different compositions, the general trends in damage formation were found similar for allxvalues studied, though displaced by about two orders of magnitude in dose, HgTe damaging much easier than CdTe. For all compositions, different types of damage seem to be created at different stages during the implantation. The results can be understood if agglomeration of point defects to extended defects followed by a redistribution of the defects to deeper lying clusters with increasing dose is assumed.

ISSN:0734-2101    

DOI:10.1116/1.575799

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

We describe theoretical and experimental investigations of the nucleation of lattice mismatch‐accommodating dislocations in the strained GexSi1−x/Si(100) system. Experimentally it is found that at lower mismatches nucleation appears to be associated with growth defects, while at higherx, surface loop nucleation is favored. Theoretical predictions of the magnitude of activation barriers for homogeneous nucleation of dislocation half‐loops at the growth surface decline dramatically with increasing lattice mismatch (higherx), with nucleation of mixed climb and glide (90°) loops favored to pure glide (60°) loops. These activation barriers for surface half‐loops are shown to be lower than previously calculated due to consideration of the random alloy nature of the GexSi1−xepilayer.

ISSN:0734-2101    

DOI:10.1116/1.575800

出版商:American Vacuum Society    

年代:1989

数据来源: AIP