Evaluation of strain and In content in (InGaN/GaN) multiquantum wells by x-ray analysis

Krost, A.; Bläsing, J.; Lünenbürger, M.; Protzmann, H.; Heuken, M.

doi:10.1063/1.124483

Cited by 27 publications

(23 citation statements)

References 9 publications

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“…Complementary XRR measurements were compared with simulations to determine the layer thicknesses (in particular t w ) so the structure could be fully characterised using X-ray scattering techniques alone. In a sense this is similar to the complementary use of HRXRD and XRR for InGaN/GaN MQWs reported previously [3]. Simulations of the specular reflection of X-rays from the structures were calculated using the recursive treatment of Parratt [4] and the effect of diffuse interfaces modelled as by Névot and Croce [5].…”

Section: X-ray Scattering Characterisation Of Sqwsmentioning

confidence: 98%

Analysis of InGaN/GaN single quantum wells by X‐ray scattering and transmission electron microscopy

Smeeton

Kappers

Barnard

et al. 2003

Physica Status Solidi (b)

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A set of In x Ga 1-x N/GaN single quantum wells (SQWs) were analysed using X-ray reflectivity (XRR), high resolution X-ray diffraction (HRXRD) and high resolution transmission electron microscopy (HRTEM). A method for determining the thickness and composition of the single quantum well layers using only X-ray scattering measurements is described -the results agree very closely with those determined from HRTEM analysis of the same samples. HRTEM lattice fringe images obtained from InGaN subjected to minimal exposure to the electron beam were used to determine local lattice parameter maps. These show the indium to be distributed uniformly within the alloy. The electron beam very rapidly caused damage to the InGaN which could be falsely interpreted as an inhomogeneous indium distribution.1 Introduction Accurate characterisation of In x Ga 1-x N quantum well (QW) widths, compositions and alloy homogeneity is an important stage in understanding the growth and optical properties of InGaN based LEDs and laser diodes. Though InGaN QW widths can be routinely measured using HRTEM, in many situations X-ray scattering measurements are advantageous over TEM experiments: they are nondestructive, average over a greater amount of material and can yield information more rapidly. Characterisation of QW structures using HRXRD relies on optimising the parameters in a model so that its simulated scattering (based on X-ray scattering theory) most closely matches the measured diffraction behaviour. For InGaN/GaN QWs lying normal to [0001] this is best achieved using an ω/2θ scan about the GaN (0002) reflection [1]. Care must be taken when using this approach since different parameters in the model can result in indistinguishable scattering simulations for scattering angles close to the primary GaN reflection. For multiple quantum well (MQW) structures it is necessary to consider the intensities of several orders of the superlattice satellite diffraction peaks to distinguish between different models which generate otherwise similar scattering [2]. This approach has recently been used to extract QW thicknesses and compositions from InGaN/GaN MQW structures with five and ten superlattice repeats [1]. The GaN (0002) ω/2θ scan from an InGaN SQW structure (Fig. 1) does not contain any superlattice satellite peaks (only thickness fringes) and the information which can be obtained in a reasonable time using a laboratory diffractometer cannot be used on its own to ascertain the structure. In this paper we describe how complementary XRR measurements were used together with the HRXRD data to determine layer thicknesses and compositions for a set of InGaN/GaN SQW structures. HRTEM analysis indicates the parameters measured by X-ray scattering to be reliable and that the InGaN alloy is homogeneous in these samples. The potential for detecting false indium clustering due to electron beam damage of the InGaN is also identified.The wurtzitic InGaN/GaN heterostructures were grown on c-plane sapphire substrates by metalorganic vapour phase epitaxy (MOVP...

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Section: X-ray Scattering Characterisation Of Sqwsmentioning

confidence: 98%

Analysis of InGaN/GaN single quantum wells by X‐ray scattering and transmission electron microscopy

Smeeton

Kappers

Barnard

et al. 2003

Physica Status Solidi (b)

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“…n-doping of the GaN buffer was performed by using 2% SiH4 in H2. Layer quality was measured by room and low temperature photoluminescence as well as by high resolution X-ray diffraction measurements [5]. RT-PL has been completely screened by full wafer mapping to get wafer uniformity information.…”

Section: Methodsmentioning

confidence: 99%

<title>Highly efficient InGaN/GaN MQW for blue- and green-light-emitting structures grown in production MOVPE reactors</title>

Bremser¹,

Luenenbuerger

Protzmann

et al. 2000

SPIE Proceedings

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Normal incidence reflectivity measurements were carried out in an AIX 2000G3HT Multiwafer Planetary Reactor® MOVPE system, a large scale production tool for GaN-based devices, and in the single wafer AIX 200 RF system. In situ monitoring was used to investigate nucleation behaviour, temperature dependence of GaN growth, and the deposition of GaN/InGaN multiquantum wells, especially the quality of interfaces. The obtained results were compared with RT photoluminescence, and high resolution X-ray measurements. The optimised SQW and MQW structures were embedded in Si and Mg doped cladding layers. Contacting the layers with simple metal electrodes without any contact processing results in an intense green electroluminescence. Electroluminescence test structures emitting at 540nmshow minimum forward voltages around 4V with a current of 20 mA. Since no contact technology is applied this is a proof of high p-type doping and excellent structural properties of the InGaN. We found a standard deviation of the wavelength at about 533nm of less than 1% across the wafer.Since these results were reproducibly obtained for structures emitting in the blue or green the basic demands of a reliable production equipment are fulfilled: a) high precursor yield (typical 20% for the Ga source) b) uniformity of electrical and optical performance c) demonstration of electroluminescence with high efficiency.

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“…The layer quality was measured by room and low temperature photoluminescence as well as by high resolution X-ray diffraction measurements [5]. RT-PL has been completely screened by full wafer mapping to get wafer uniformity information.…”

Section: Methodsmentioning

confidence: 99%

Interface Treatment of GaN/InGaN-Multi Quantum Well Structures Grown in Production Type MOVPE Systems

Protzmann¹,

Lünenbürger²,

Bläsing³

et al. 1999

phys. stat. sol. (a)

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Evaluation of strain and In content in (InGaN/GaN) multiquantum wells by x-ray analysis

Cited by 27 publications

References 9 publications

Analysis of InGaN/GaN single quantum wells by X‐ray scattering and transmission electron microscopy

Analysis of InGaN/GaN single quantum wells by X‐ray scattering and transmission electron microscopy

<title>Highly efficient InGaN/GaN MQW for blue- and green-light-emitting structures grown in production MOVPE reactors</title>

Interface Treatment of GaN/InGaN-Multi Quantum Well Structures Grown in Production Type MOVPE Systems

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