the properties of long wavelength strained layer superlattice lasers grown by MOVPE

Monserral, K. J.; Tothill, J.N.

doi:10.1007/bf02657775

Cited by 15 publications

(4 citation statements)

References 10 publications

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“…The GaInAs/GaAs system is one of the most popular strained systems, 6 and its relaxation process under high strain has been extensively investigated. 7,8 However, it has not been fully clarified yet whether the relaxation process and its mechanism in GaInNAs/GaAs are really similar to those in GaInAs/GaAs.…”

Section: Introductionmentioning

confidence: 99%

Structural characterization of GaInNAs/GaAs double quantum well structures

Nakashima¹,

Tateno²

2004

Journal of Applied Physics

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We performed a structural analysis of strained GaInNAs/GaAs double quantum well samples (about 2% N content) having various well-layer thicknesses and investigated the relaxation process beyond the critical thickness. We used photoluminescence (PL) measurements, x-ray diffraction measurements, and transmission electron microscopy (TEM) analysis. PL measurement reveals deterioration of crystal quality as the well thickness increases. X-ray diffraction reveals that no serious relaxation occurs even when the deterioration proceeds. Cross-sectional and plan-view TEM analysis clarify the deterioration process in detail. In a sample with thin well layers, local dark spots are first generated only at the first well layer, whereas no such dark spots are observed in the second well layer. Through careful observation, the dark spots are identified as local defects (dislocation loop), not the quantum dot structures reported for other materials. For samples with thicker wells, large dark spots penetrating both well layers are observed. Furthermore, threading dislocations and/or stacking faults, which derive from the dark spots, are also observed in the upper GaAs cladding layers. However, no misfit dislocations are observed in any samples, although two-dimensional growth is confirmed. These results indicate a different type of deterioration from that conventionally reported in InGaAs/GaAs material systems. The relationships between the deterioration process and growth process are discussed based on the interface smoothness. The discussion clarifies that dynamical processes play essential roles in the deterioration.

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Section: Introductionmentioning

confidence: 99%

Structural characterization of GaInNAs/GaAs double quantum well structures

Nakashima¹,

Tateno²

2004

Journal of Applied Physics

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“…The strained layer superlattice (SLS) structure has become indispensable in obtaining high-performance optoelectronic devices. The advantages of the SLS have been investigated and demonstrated by applying it to various optoelectronic devices (Osbourn, 1986;Zipperian et al, 1988;Kolbas et al, 1988;Monserrat & Tothill, 1989). For further improvement of device performance, highly strained SLS structures are required.…”

Section: Introductionmentioning

confidence: 99%

A new version of the method for analysing peak broadening caused by local tilt distribution in double-crystal X-ray diffraction measurements

Nakashima¹

2000

J Appl Cryst

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A new method of analysing X‐ray peak broadening caused by local tilt distribution in mosaic structures is proposed for double‐crystal X‐ray diffraction measurements. In the new method, the dependence of whole peak profiles on various reflection indices hkl is analysed, whereas that of only the peak full width at half‐maximum (FWHM) is analysed in a conventional broadening analysis. The theoretical formula tells us that not only the FWHM values but also the whole profiles become independent of hkl after rescaling the horizontal axis Δθ of measured patterns to Δθ/cosθc, where θc is the angle between the (001) and (hkl) planes. A new criterion is proposed to judge whether X‐ray peak broadening is caused by the local tilt distribution or not; the advantage provided by the new criterion, using whole peak profiles, is high accuracy in making this judgment. It is experimentally verified that the hkl independence holds in terms of whole peak profiles. The advantage of the method is demonstrated experimentally by applying it to InAsP/InGaAsP strained layer superlattice samples.

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“…The GaInNAs material system is similar to the GaInAs/ GaAs system in that the N content in both is small. The GaInAs/GaAs system is one of the most popular strained systems (Monserrat & Tothill, 1989) and the relaxation process under high strain has been extensively investigated (Fitzgerald et al, 1988;Herbeaux et al, 1989). However, it has not been fully clari®ed yet whether the relaxation process and its mechanism in the GaInNAs system are really similar to those in GaInAs/GaAs.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction analysis of GaInNAs double-quantum-well structures

Nakashima¹,

Tateno²

2004

J Appl Cryst

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The structures of GaInNAs/GaAs double‐quantum‐well (DQW) samples with various well‐layer thicknesses were analysed by X‐ray diffraction measurements. Two types of rocking‐curve analysis were applied with different scanning configurations: a conventional configuration without a receiving slit and one with an analyser crystal placed in front of the receiving detector (the latter is the same as that usually used in reciprocal‐space mapping measurements). It was found that systematic combination of both types of analysis is essential for the characterization of the sample structures. The two types of X‐ray profiles obtained using the different scanning configurations exhibit a considerable difference in intensity as the thickness of the well layers increases. The increasing difference clearly indicates deterioration of the DQW structures. The two profiles exhibit little difference in terms of shape, merely showing that the DQW layers are coherently strained relative to the substrate. This implies that measurement in only one of the configurations is insensitive to the deterioration and leads to the wrong conclusion that a sample has a perfect structure without dislocations and defects. Photoluminescence and transmission electron microscope analyses both reveal that defects really do exist in the DQW structures, which is consistent with the difference in intensity observed in the X‐ray measurements. From these results, a clear picture that consistently explains the sensitivity of X‐ray diffraction analysis to the deterioration of samples is presented. In addition, based on this picture, it is proposed that the procedure of comparing the two types of profiles represents a new type of analysis method for the precise characterization of samples.

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the properties of long wavelength strained layer superlattice lasers grown by MOVPE

Cited by 15 publications

References 10 publications

Structural characterization of GaInNAs/GaAs double quantum well structures

Structural characterization of GaInNAs/GaAs double quantum well structures

A new version of the method for analysing peak broadening caused by local tilt distribution in double-crystal X-ray diffraction measurements

X-ray diffraction analysis of GaInNAs double-quantum-well structures

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