Activation of arsenic as an acceptor in Hg1−xCdxTe under equilibrium conditions

Chandra, D.; Schaake, H. F.; Kinch, M. A.; Aqariden, F.; Wan, C. F.; Weirauch, D. F.; Shih, H. D.

doi:10.1007/s11664-002-0225-1

Cited by 19 publications

(11 citation statements)

References 6 publications

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“…After a high-temperature (400°C to 500°C) anneal followed by a mercury vacancy-filling anneal, again under Hg saturation, the layers measure p-type with approximately 100% activation. [5][6][7] p-Type layers (albeit with reduced activation) were also achieved when annealed at Te (tellurium) saturation. Formation of arsenic telluride (As 2 Te 3 ) has previously been cited for the As inactivity.…”

Section: Literature Review Of Arsenic Doping In Mctmentioning

confidence: 99%

As Doping in (Hg,Cd)Te: An Alternative Point of View

Hails

Irvine

Cole‐Hamilton

et al. 2008

Journal of Elec Materi

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Acceptor doping of many II-VI compound semiconductors has proved problematic and doping of epitaxial mercury cadmium telluride (MCT, Hg 1-x Cd x Te) with arsenic is no exception. High-temperature (>400°C) anneals followed by a lower temperature mercury-rich vacancy-filling anneal are frequently required to activate the dopant. The model frequently used to explain p-type doping with arsenic invokes an amphoteric nature of group V atoms in the II-VI lattice. This requires that group VI substitution with arsenic only occurs under mercury-rich conditions either during growth or the subsequent annealing and involves site switching of the As. However, there are inconsistencies in the amphoteric model and unexplained experimental observations, including arsenic which is 100% active as grown by metalorganic vapor-phase epitaxy (MOVPE). A new model, based on hydrogen passivation of the arsenic, is therefore proposed.

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Section: Literature Review Of Arsenic Doping In Mctmentioning

confidence: 99%

As Doping in (Hg,Cd)Te: An Alternative Point of View

Hails

Irvine

Cole‐Hamilton

et al. 2008

Journal of Elec Materi

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“…Quantitatively, more than 50% of the arsenic incorporated during the epigrowth already appears to occupy sites in the Te sublattice immediately following the growth and prior to any "site transfer" activation anneals. 9 However, a portion of the total arsenic, ranging to less than 50%, did not appear to be activated as acceptors. 9 The true form of this arsenic has not been conclusively established, but can be approximated by assuming it to be behaving similar to a donor.…”

Section: Resultsmentioning

confidence: 95%

Growth of very low arsenic-doped HgCdTe

Chandra¹,

Weirauch²,

Schaake³

et al. 2005

Journal of Elec Materi

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Arsenic is known to be an amphoteric impurity that may occupy either sublattice in HgCdTe depending upon sample annealing. As an acceptor in low concentrations, it offers several features that are attractive for the fabrication of certain nϩ-on-p detector diode structures. The epitaxial growth of arsenic-doped HgCdTe from a Te-rich melt can fulfill the requirements for application in a variety of devices where low vacancy concentrations and low defect densities are critical requirements in minimizing dark currents. These devices may include the high operating temperature (HOT) detectors operated in a strong nonequilibrium and reverse bias mode to suppress the Auger-generated dark currents. For the materials' growth process to be effective, the segregation coefficient determining the incorporation of arsenic from the Te-rich melt needs to be established. This coefficient was measured during these investigations and was observed to vary with arsenic concentration. Within the range of interest, this parameter varied between 8 ϫ 10 Ϫ6 and 1 ϫ 10 Ϫ4 . These extremely small values limit the doping that can be achieved to <5 ϫ 10 16 cm Ϫ3 in the grown epifilm. Furthermore, the large addition of arsenic to the melt, necessitated by the extremely small segregation coefficients, leads to a condition where the concentration of arsenic in the liquid-phase epitaxy (LPE) nutrient melt exceeds that of cadmium. The melt chemistry, phase diagram, and epigrowth process fundamentally change as a result. This new epigrowth process was developed and tuned during these investigations. For acceptor levels at 1 ϫ 10 15 cm Ϫ3 and lower, the growth of arsenic-doped HgCdTe from a Te-rich LPE melt has been determined to be an extremely reproducible, powerful, and controllable technique.

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“…1 For introducing arsenic at higher levels, an infinite-melt Hg-rich LPE can be employed. 1 As incorporated employing the Te-saturated liquid-phase epitaxy process, a significant fraction of this arsenic, but contrary to a possible common misconception, not the majority fraction, 1 may remain on sites in the metal sublattice and act as donors. A metal (Hg)-saturated annealing, preferably above 350°C, is required to transfer these arsenic atoms to sites on the Te sublattice, following which these act as acceptors.…”

Section: Introductionmentioning

confidence: 99%

“…A metal (Hg)-saturated annealing, preferably above 350°C, is required to transfer these arsenic atoms to sites on the Te sublattice, following which these act as acceptors. 1 No such activation annealing appears to be necessary for arsenic incorporated from the Hg-rich liquid-phase epitaxy process. However, following either the metal-saturated activation annealing for arsenic incorporated from the Te-rich liquid-phase epitaxy process, or for arsenic incorporated from the Hg-rich liquid-phase epitaxy process, the activated arsenic coexists with a metal vacancy concentration formed during the anneal itself.…”

Section: Introductionmentioning

confidence: 99%

“…This final anneal ensures that, in both cases, the residual Hg vacancy concentration stays at magnitudes less than 1 ϫ 10 13 cm Ϫ3 , with the result that the net acceptor concentration, as determined by the Hall measurements, agrees with the actual concentration of arsenic present, for epifilms grown either from the Te-rich LPE process or the Hg-rich LPE process, as determined by secondary ion mass spectrometry (SIMS). 1 Diode formation at DRS is by the introduction of a damage process. Arsenic doping is of relevance here as a means of producing lightly p-doped HgCdTe for use in forming high density vertically integrated photodiode (HDVIP) diodes.…”

Section: Introductionmentioning

confidence: 99%

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