Improving material characteristics and reproducibility of MBE HgCdTe

Edwall, D. D.; Zandian, Majid; Chen, A. C.; Arias, J. M.

doi:10.1007/s11664-997-0183-8

Cited by 41 publications

(21 citation statements)

References 5 publications

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“…Further details can be found in our earlier publications. [3][4][5][6][7][8] Indium was used as the dopant for n-type layers. The p-type layers doped with As were grown using both a conventional As 4 source and a cracker cell with the cracker element operating at 700°C to produce As 2 molecules from evaporated As 4 .…”

Section: Methodsmentioning

confidence: 99%

Molecular beam epitaxy growth of high-quality arsenic-doped HgCdTe

Edwall

Piquette

Ellsworth

et al. 2004

Journal of Elec Materi

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We have initiated a joint effort to better elucidate the fundamental mechanisms underlying As-doping in molecular beam epitaxy (MBE)-grown HgCdTe. We have greatly increased the As incorporation rate by using an As cracker cell. With a cracker temperature of 700°C, As incorporation as high as 4 ϫ 10 20 cm Ϫ3 has been achieved by using an As-reservoir temperature of only 175°C. This allows the growth of highly doped layers with high quality as measured by low dislocation density. Annealing experiments show higher As-activation efficiency with higher anneal temperatures for longer time and higher Hg overpressures. Data are presented for layers with a wide range of doping levels and for layer composition from 0.2 to 0.6.

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Section: Methodsmentioning

confidence: 99%

Molecular beam epitaxy growth of high-quality arsenic-doped HgCdTe

Edwall

Piquette

Ellsworth

et al. 2004

Journal of Elec Materi

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“…The mechanism of formation and cause of defects are very complex and diverse. Different authors and groups agree that voids and micro-voids are directly related to Hg fluxes and substrate growth temperature [7][8][9]. A thermodynamic approach for void and micro-void prevention can be found at Ref.…”

Section: X-ray Rocking Curvesmentioning

confidence: 99%

Hg_(1‐x)Cd_xTe from short to long wave infrared on Si substrates grown by MBE

Vilela

Olsson

Reddy

et al. 2010

Phys. Status Solidi (c)

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In this paper, we show the power of using molecular beam epitaxy (MBE) for the growth of the mercury cadmium telluride (HgCdTe) system. Abrupt composition profiles, changes in doping levels, or switching doping types are easily performed. It is shown that high quality material is achieved with Hg(1‐x)CdxTe grown by MBE from a cadmium mole fraction of x =0.15 to x =0.72. Doping elements incorporation as low as 1015 cm‐3 for both n‐type and p‐type material as well as high incorporation levels >1018cm‐3 for both carrier types were achieved. Secondary ion mass spectrometry (SIMS) data, x‐ray data, Hall data, the influence of doping incorporation with cadmium content and growth rate, etch pit density (EPD), composition uniformity determined from Fourier transform infrared (FTIR) transmission spectroscopy, and surface defect maps from low to high x values are presented to illustrate the versatility and quality of HgCdTe material grown by MBE. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…The electron mobility in the annealed-HgCdTe layer UWA54 is comparable to that obtained by other workers for high-quality HgCdTe of the same composition. 3 The as-grown layer UWA54 exhibits classical ptype conduction, thought to be due to Hg vacancies in the bulk, whereas the annealed layer shows two n-type carriers with the lower mobility carrier being attributed to a surface inversion layer. The second layer considered in this work, UWA56, was also annealed and measured in the same way, and the resulting mobility spectra is almost identical to that of the annealed layer UWA54, as evident by comparing Figs.…”

Section: Electrical Characterizationmentioning

confidence: 99%

Laser-beam-induced current mapping of spatial nonuniformities in molecular beam epitaxy As-grown HgCdTe

Sewell

Musca

Antoszewski

et al. 2004

Journal of Elec Materi

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The formation of dislocations and corresponding built-in electric fields in molecular beam epitaxy (MBE)-grown HgCdTe can have a major impact on the performance and yield of photodetectors fabricated from this material. This paper investigates the presence of such built-in electric fields arising from dislocation segregation in MBE as-grown HgCdTe, and their subsequent removal via a low-temperature Hg-saturated anneal. The electrical properties and surface morphology of an HgCdTe layer grown on a thin CdTe buffer layer are compared with those of an HgCdTe layer grown directly on the CdZnTe substrate. Laser-beam-induced current (LBIC) imaging is a nondestructive technique capable of mapping built-in electric fields present in a semiconductor material, which, in the present case, has been used to reveal dislocation distributions present in as-grown, unintentionally doped, MBE-grown Hg 0.71 Cd 0.29 Te. Two-dimensional scanning LBIC measurements at 160 K allow spatial mapping of electric fields across the HgCdTe wafer. Subsequent isothermal annealing of the wafer in an Hg atmosphere has been found to decrease the magnitude of the built-in electric fields to below the LBIC detection limit. However, of particular note, is that before and after annealing, crosshatch patterns can be seen using Nomarski microscopy, with the crosshatching being predominantly in the [011 -] direction and, to a lesser extent, in the [2 -31] and [2 -13] directions. Defect-decoration etching of the annealed wafer reveals dislocation banding parallel to the [011 -] direction, which closely resembles the contrast observed in the LBIC image of the wafer before annealing. These Nomarski and LBIC images are compared with those of a second wafer, which incorporates a 40-nm CdTe buffer layer. The second wafer does not show significant Nomarski or LBIC contrast, indicating a flat, electrically uniform as-grown layer. Variable magnetic-field Hall measurements at 77 K and quantitative mobility-spectrum analysis (QMSA) indicate predominately p-type conduction with a doping density of 2 ϫ 10 15 cm Ϫ3 in the as-grown layer. After Hg annealing at 240°C, no LBIC signals are observed at 160 K, and Hall measurements at 77 K indicate the presence of two n-type carriers, with a combined doping density of 2 ϫ 10 15 cm Ϫ3 . Double-crystal x-ray diffraction measurements show no evidence of twinned crystal volumes in the layers before or after annealing, or any change in the full-width at half-maximum (FWHM) (41 arcsec) of the (422) reflection. The similarity between the dislocation density distribution, as revealed by defect decoration, and the LBIC image suggests that Hg out-diffusion during growth is expedited in regions of high dislocation concentration, thus creating a nonuniform Hg vacancy-acceptor concentration. The as-grown acceptor concentration, in turn, modulates the hole concentration, creating p ϩ /p Ϫ junctions and built-in electric fields in the material. Low-temperature annealing in a saturated-Hg atmosphere does not remove the crosshatch patterns or...

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Improving material characteristics and reproducibility of MBE HgCdTe

Cited by 41 publications

References 5 publications

Molecular beam epitaxy growth of high-quality arsenic-doped HgCdTe

Molecular beam epitaxy growth of high-quality arsenic-doped HgCdTe

Hg_(1‐x)Cd_xTe from short to long wave infrared on Si substrates grown by MBE

Laser-beam-induced current mapping of spatial nonuniformities in molecular beam epitaxy As-grown HgCdTe

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Improving material characteristics and reproducibility of MBE HgCdTe

Cited by 41 publications

References 5 publications

Molecular beam epitaxy growth of high-quality arsenic-doped HgCdTe

Molecular beam epitaxy growth of high-quality arsenic-doped HgCdTe

Hg(1‐x)CdxTe from short to long wave infrared on Si substrates grown by MBE

Laser-beam-induced current mapping of spatial nonuniformities in molecular beam epitaxy As-grown HgCdTe

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Hg_(1‐x)Cd_xTe from short to long wave infrared on Si substrates grown by MBE