Real-Time In Situ Monitoring of GaAs (211) Oxide Desorption and CdTe Growth by Spectroscopic Ellipsometry

Lennon, C. M.; Almeida, L. A.; Jacobs, R. N.; Markunas, J. K.; Smith, Paul J.; Arias, J.; Brown, Alexander; Pellegrino, John

doi:10.1007/s11664-012-2088-4

Cited by 8 publications

(3 citation statements)

References 22 publications

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“…21 A limited number of studies have been conducted so far to investigate the structural properties of CdTe/GaAs heterostructures by X-ray diffraction (XRD) techniques. The dependence of the structural properties on the growth temperatures, 22 the effect of the residual stresses, 6 the role of thermal expansion matching, 23 the lattice tilting of CdTe epilayers, 24 and fullwidth at half-maximum (FWHM) values of the X-ray double-crystal rocking curve (XDRC) measurements 25 were studied in real space. In our previous study, 26 the screw TDs and shear strain coexisting in the CdTe epilayer were evaluated with the help of RSM.…”

Section: Introductionmentioning

confidence: 99%

Identifying threading dislocations in CdTe films by reciprocal space mapping and defect decoration etching

Polat

Bilgilisoy

Arı

et al. 2018

Journal of Applied Physics

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We study threading dislocation (TD) density of high-quality cadmium telluride (CdTe) layers grown on a (211) oriented GaAs substrate by molecular beam epitaxy. High-resolution X-ray diffraction was performed to calculate the density of screw-type TDs by measuring the broadening of the asymmetrical (511) Bragg reflections of CdTe epilayers. In addition, total TD densities were determined by the Everson-etching method and were compared with screw TDs. Our results show that the total TD densities in CdTe films were dominated by those with screw character. The screw component TDs are estimated to account for more than 90% of the total TD density.CdTe layers grown at a thickness of less than 3.0 lm typically exhibit the screw TD densities in the 10 6 cm -2 and 10 7 cm -2 range. It can be noted that as the nucleation temperature increases, i.e., !222 C, both the area density of TDs with the screw component of the CdTe films and the total TD density are roughly four times larger than those of the epilayer grown at the nucleation temperature of 215 C. Furthermore, we discuss the influence of the II/VI flux ratio on the density of threading dislocations. The contribution of screw TDs to the total TD density showed a significant decrease in roughly 30% in the case of a high II/VI flux ratio. We further examine the reciprocal space maps in the vicinity of the (422) reflections.

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Section: Introductionmentioning

confidence: 99%

Identifying threading dislocations in CdTe films by reciprocal space mapping and defect decoration etching

Polat

Bilgilisoy

Arı

et al. 2018

Journal of Applied Physics

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“…To reduce the overall manufacturing costs of HgCdTe detectors, CdTe-buffered substrates, including Si(211), GaAs(211)B, and Ge(211)B, have been utilized and have been the subject of much study. [1][2][3][4][5] Compared to CdZnTe, these substrates cost (/cm 2 ) orders of magnitude less, and are available in much larger sizes. They are less soft, less brittle, easier to manufacture, and widely used in current semiconductor processing facilities.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Curvature and Stress Studies for MBE CdTe on Si and GaAs Substrates

Jacobs

Vasquez

Lennon

et al. 2015

Journal of Elec Materi

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Infrared focal plane arrays (IRFPA) based on HgCdTe semiconductor alloys have been shown to be ideal for tactical and strategic applications. High density (>1 M pixel), high operability HgCdTe detectors on large area, lowcost composite substrates, such as CdTe-buffered Si or GaAs, are envisioned for next-generation IRFPAs. Thermal expansion mismatch is among various material parameters that govern the structural properties of the final detector layer. It has previously been shown that thermal expansion mismatch plays the dominant role in the residual stress characteristics of these heteroepitaxial structures (Jacobs et al. in J Electron Mater 37:1480. The wafer curvature (bowing) resulting from residual stress, is a likely source of problems that may occur during subsequent processing. This includes cracking of the film and substrate during post-growth annealing processes or even certain characterization techniques. In this work, we examine dynamic curvature and stress during molecular beam epitaxy (MBE), of CdTe on Si and GaAs substrates. The effect of temperature changes on wafer curvature throughout the growth sequence is documented using a multi-beam optical sensor developed by K-Space Associates. This monitoring technique makes possible the study of growth sequences which employ annealing schemes and/or interlayers to influence the final residual stress state of the heteroepitaxial structures.

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“…Each one of these factors make the structure being examined extremely difficult to analyze, especially with the traditional x-ray diffraction (XRD) methods. As a result, a limited number of studies so far have been dedicated to understanding the structural properties of this heterostructure [5][6][7][8]. The common point of all these studies is that they were carried out in real space.…”

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confidence: 99%

Reciprocal space mapping study of CdTe epilayer grown by molecular beam epitaxy on (2 1 1)B GaAs substrate

Polat¹,

Arı²,

Öztürk³

et al. 2017

Mater. Res. Express

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Reciprocal space mapping (RSM) has been widely utilized to find out the microstructure and deviations from ideal crystal structures, present in materials ranging from polycrystalline to single-crystalline [1]. RSM can deliver further structural information as compared to conventional methods such as rocking curve (RC) scan due to its two-dimensional (2D) characteristics [2]. This particularly provides a significant advantage when applied to epitaxial thin films having large lattice mismatches. Nondestructive measurement of the threading-dislocation (TD) densities, for instance, relies on prediction of individual parameters, such as domain tilt and twist, of a mosaic layer structure [3]. In addition to the large lattice mismatch, some epitaxial heterostructures have also the low-symmetry surface characteristics. CdTe/(2 1 1)B GaAs is obviously one of the outstanding examples of these types of structures. Structural analysis of the high-index oriented zinc-blende epitaxial layers when combined with the large lattice mismatch becomes much more challenging. Furthermore, the surface normal of epilayer lattice tilts approximately 3° with respect to that of substrate [4]. Each one of these factors make the structure being examined extremely difficult to analyze, especially with the traditional x-ray diffraction (XRD) methods. As a result, a limited number of studies so far have been dedicated to understanding the structural properties of this heterostructure [5][6][7][8]. The common point of all these studies is that they were carried out in real space. However, one advantageous option can be mapping in reciprocal space to characterize such heterostructures. At present, the technique has been separately applied to the high-index orientation [9] or to the large lattice mismatched heterostructures [10].In this letter, the RSM technique is effectively employed to study the lattice tilting, the lattice mismatches, the shear strain produced by the low-symmetry surface and the screw dislocation density of CdTe epilayer grown on (2 1 1) oriented GaAs substrate. Experimental procedure Molecular beam epitaxy (MBE) growth of CdTeThe growth details were similar to those described elsewhere [11,12]. Briefly, CdTe epilayer was grown by molecular beam epitaxy (MBE) system operated in a class 1000 cleanroom environment on a 3-inch epi-ready, semi-insulating (2 1 1)B GaAs wafer after thermal stripping of the oxide layer. Initially, a nucleation layer also

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Real-Time In Situ Monitoring of GaAs (211) Oxide Desorption and CdTe Growth by Spectroscopic Ellipsometry

Cited by 8 publications

References 22 publications

Identifying threading dislocations in CdTe films by reciprocal space mapping and defect decoration etching

Identifying threading dislocations in CdTe films by reciprocal space mapping and defect decoration etching

Dynamic Curvature and Stress Studies for MBE CdTe on Si and GaAs Substrates

Reciprocal space mapping study of CdTe epilayer grown by molecular beam epitaxy on (2 1 1)B GaAs substrate

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