Low dislocation density MBE process for CdTe-on-GaSb as an alternative substrate for HgCdTe growth

Lei, Wen; Ren, Yuchen; Madni, Imtiaz; Faraone, Lorenzo

doi:10.1016/j.infrared.2018.05.010

Cited by 23 publications

(8 citation statements)

References 16 publications

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“…[15] As shown in Figure 1b, an ω scan full width at half maximum (FWHM) (full width at half maximum) value of 306 arc sec is achieved for the direct growth of HgCdTe on mica, which is three-to five-times larger than that of (Hg)CdTe layers grown on conventional alternative substrates such as Si, Ge, GaAs, and GaSb, with state-of-the-art CdTe buffer layer technology. [3,[16][17][18] Note that the relatively larger XRD FWHM measured for the HgCdTe on mica sample may be caused by imperfect cleavage of the mica substrate during substrate preparation prior to film growth, defects such as twins and dislocations generated during MBE growth, as well as substrate bowing due to its flexibility.…”

Section: Resultsmentioning

confidence: 99%

Van der Waals Epitaxy of HgCdTe Thin Films for Flexible Infrared Optoelectronics

Pan

Zhang

et al. 2022

Adv Materials Inter

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performance, such as fast response, tailorable bandgap over the 1-30 µm range, and high quantum efficiency, HgCdTebased IR photodetectors grown on latticematched Cd 0.96 Zn 0.04 Te (CZT) substrates and associated focal plane arrays (FPAs) dominate the high-performance end of IR applications. [1] The further development of IR applications requires the future HgCdTe IR detectors to have new features of lower cost, larger array format size, higher operating temperature, larger field of view (FOV), and multiband detection. [2] Over the past 10-20 years, significant progress has been achieved in these areas. For example, alternative substrates (Si, Ge, GaAs, and GaSb) instead of the traditional CZT substrates were researched for growing HgCdTe IR materials in order to fabricate nextgeneration IR imaging FPAs with lower cost and larger array format. [3][4][5] Recently curved imaging FPAs have been proposed as a feasible approach for achieving larger FOV with simpler and flatter lenses in comparison to conventional planer FPAs. [2] The conventional development pathway of these curved imaging FPAs relies on substrate thinning and FPA bending, which is inherently limited due to complex device processing, low yield, and high cost. Note that II-VI HgCdTe materials are more vulnerable to damage during the substrate-thinning processes because they are much more fragile and sensitive to chemical/mechanical damage in comparison to conventional Group IV and III-V semiconductors. In addition, the process does not remove the substrate completely due to the variability limits of array alignment on the polishing tool. Consequently, both the flexibility of the thinned FPA and the feasibility of monolithic integration are also limited in comparison to what could be achieved if transferable and/or free-standing HgCdTe device active layer of thickness <10 µm was available.Two-dimensional (2D)-layered materials such as graphene and mica have the potential to serve as substrates for growing high-quality three-dimensional (3D) semiconductor thin films through van der Waals epitaxy (vdWE) techniques such as molecular beam epitaxy (MBE) and MOCVD. [6] For vdWE growth, the stringent requirement of matched lattice constants for highquality heterostructure growth in traditional semiconductor epitaxy is mitigated. This is because the 2D-layered substrates have naturally passivated surfaces and strong chemical bonding is not required at the interface. In this way, the generation of dislocations at the interface can be effectively suppressed. [7,8] Van der Waals epitaxial (vdW) growth of semiconductor thin films on 2D layered substrates has recently attracted considerable attention since it provides a potential pathway for realizing monolithically integrated devices and flexible devices. In this work, direct growth of epitaxial HgCdTe (111) thin films on 2D layered transparent mica substrates is achieved via molecular beam epitaxy. The full width at half maximum of the ω-mode X-ray diffraction peak is measured to be around 306 arc sec. Mid-wave in...

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Section: Resultsmentioning

confidence: 99%

Van der Waals Epitaxy of HgCdTe Thin Films for Flexible Infrared Optoelectronics

Pan

Zhang

et al. 2022

Adv Materials Inter

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“…11 Most recently, GaSb substrates have been proposed as a new alternative to replace CdZnTe for growing high-quality HgCdTe/CdTe/GaSb. [12][13][14] In comparison to Si, Ge and GaAs, the mismacth in lattice constant and CTE (coefficient of thermal expansion) between HgCdTe and GaSb is much lower, which should result in a lower TD density in CdTe and HgCdTe epitaxial layers. Preliminary work has been undertaken to improve the quality of MBE grown CdTe on GaSb by inserting a nearly lattice-matched transitional Zn(Cd)Te layer between the GaSb substrate and the CdTe buffer layer, 12 which has led to an EPD of 1.4 9 10 5 cm À2 in the CdTe layer that is lower than values ranging from mid-10 5 cm À2 to mid-10 6 cm À2 reported on Si, Ge and GaAs substrates.…”

Section: Introductionmentioning

confidence: 99%

“…[12][13][14] In comparison to Si, Ge and GaAs, the mismacth in lattice constant and CTE (coefficient of thermal expansion) between HgCdTe and GaSb is much lower, which should result in a lower TD density in CdTe and HgCdTe epitaxial layers. Preliminary work has been undertaken to improve the quality of MBE grown CdTe on GaSb by inserting a nearly lattice-matched transitional Zn(Cd)Te layer between the GaSb substrate and the CdTe buffer layer, 12 which has led to an EPD of 1.4 9 10 5 cm À2 in the CdTe layer that is lower than values ranging from mid-10 5 cm À2 to mid-10 6 cm À2 reported on Si, Ge and GaAs substrates. 15,16 However, the Zn(Cd)Te transitional layer is specific to the GaSb substrate due to the unique feature that GaSb and ZnTe are nearly lattice-matched, and thus may not be applicable to the growth of CdTe on other alternative substrates.…”

Section: Introductionmentioning

confidence: 99%

Strained CdZnTe/CdTe Superlattices As Threading Dislocation Filters in Lattice Mismatched MBE Growth of CdTe on GaSb

Pan

Zhang

et al. 2020

Journal of Elec Materi

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In this work, multiple sets of CdZnTe/CdTe strained-layer superlattices have been used as dislocation filtering layers for reducing the threading dislocations and improving the material quality of CdTe buffer layers grown by molecular beam epitaxy (MBE) on GaSb (211)B substrates. By incorporating a CdZnTe/CdTe superlattice filtering structure, a significant improvement in material quality has been achieved, with a low etch pit density of $ 1 9 10 5 cm À2 demonstrated for CdTe grown on GaSb, which is two orders of magnitude lower than previously reported values for CdTe grown directly on lattice mismatched substrates, and is comparable to values for state-of-the-art CdTe grown on lattice matched CdZnTe substrates. The filtering efficiency for each set of dislocation filtering layers has been determined to be approximately 70%. This approach provides a promising pathway towards achieving hetero-epitaxy of high quality HgCdTe on large-area lattice-mismatched alternative substrates with a low dislocation density for the fabrication of next generation infrared detectors with features of lower cost and larger array format size.

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“…16−18 It can be reduced to a 10 5 cm −2 range while being grown by a molecular beam epitaxial process. 19 Dislocations are often considered detrimental to solar cell performance because they usually serve as nonradiative recombination centers limiting carrier lifetimes and are responsible for scattering carriers and reducing their mobilities. 20,21 Limiting the scope of such undesired effects by decreasing the density of dislocation became one of the major challenges.…”

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confidence: 99%

“…CdTe, as a typical zinc-blende structure semiconductor, is an important polycrystalline thin-film solar cell absorber material, which is currently used to fabricate low-cost and high-efficiency solar cell modules. − High densities of dislocations, usually in the range of 10 6 –10 11 cm –2 , are present in typical CdTe thin films grown by physical vapor deposition, close-space sublimation, or sputter deposition. − It can be reduced to a 10 5 cm –2 range while being grown by a molecular beam epitaxial process . Dislocations are often considered detrimental to solar cell performance because they usually serve as nonradiative recombination centers limiting carrier lifetimes and are responsible for scattering carriers and reducing their mobilities. , Limiting the scope of such undesired effects by decreasing the density of dislocation became one of the major challenges.…”

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confidence: 99%

Hole-Induced Spontaneous Mutual Annihilation of Dislocation Pairs

Chen

et al. 2019

J. Phys. Chem. Lett.

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Dislocations are always observed during crystal growth, and it is usually desirable to reduce the dislocation density in high-quality crystals. Here, the annihilation process of the 30°Shockley partial dislocation pairs in CdTe is studied by first-principles calculations. We found that the dislocations can glide relatively easily due to the weak local bonding. Our systematic study of the slipping mechanism of the dislocations suggests that the energy barrier for the annihilation process is low. Band structure calculations reveal that the band bending caused by the charge transfer between the two dislocation cores depends on the core−core distance. A simple linear model is proposed to describe the mechanism of formation of the dislocation pair. More importantly, we demonstrate that hole injection can affect the core structure, increase the mobility, and eventually trigger a spontaneous mutual annihilation, which could be employed as a possible facile way to reduce the dislocation density.

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Low dislocation density MBE process for CdTe-on-GaSb as an alternative substrate for HgCdTe growth

Cited by 23 publications

References 16 publications

Van der Waals Epitaxy of HgCdTe Thin Films for Flexible Infrared Optoelectronics

Van der Waals Epitaxy of HgCdTe Thin Films for Flexible Infrared Optoelectronics

Strained CdZnTe/CdTe Superlattices As Threading Dislocation Filters in Lattice Mismatched MBE Growth of CdTe on GaSb

Hole-Induced Spontaneous Mutual Annihilation of Dislocation Pairs

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