Structural, electrical and optical properties of in-situ phosphorous-doped Ge layers

Hartmann, Jean‐Michel; Barnes, Jean‐Paul; Veillerot, M.; Fédéli, Jean-Marc; Guillaume, Q. Benoit À La; Calvo, V.

doi:10.1016/j.jcrysgro.2012.03.023

Cited by 35 publications

(38 citation statements)

References 25 publications

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“…To achieve this goal, donor implantation has been pursued by several groups, 2-8 while other authors emphasize the advantages of in-situ doping. [9][10][11][12][13][14][15][16][17][18][19] Regardless of the specific approach, the implicit assumption underlying this quest is that germanium deviates strongly from the incomplete donor ionization predicted when the doping level is so high that E d -l ) k B T is no longer valid (Here, E d is the donor energy level, l the Fermi level, k B Boltzmann's constant, and T the absolute temperature). Otherwise, a carrier concentration of 5 Â 10 19 cm À3 at room temperature would be unattainable, since it would require an atomic donor concentration of 2 Â 10 21 cm…”

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confidence: 99%

Frustrated incomplete donor ionization in ultra-low resistivity germanium films

Senaratne

Kouvetakis

et al. 2014

Applied Physics Letters

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The relationship between carrier concentration and donor atomic concentration has been determined in n-type Ge films doped with P. The samples were carefully engineered to minimize non-active dopant incorporation by using specially designed P(SiH3)3 and P(GeH3)3 hydride precursors. The in situ nature of the doping and the growth at low temperatures, facilitated by the Ge3H8 and Ge4H10 Ge sources, promote the creation of ultra-low resistivity films with flat doping profiles that help reduce the errors in the concentration measurements. The results show that Ge deviates strongly from the incomplete ionization expected when the donor atomic concentration exceeds Nd = 1017 cm−3, at which the energy separation between the donor and Fermi levels ceases to be much larger than the thermal energy. Instead, essentially full ionization is seen even at the highest doping levels beyond the solubility limit of P in Ge. The results can be explained using a model developed for silicon by Altermatt and coworkers, provided the relevant model parameter is properly scaled. The findings confirm that donor solubility and/or defect formation, not incomplete ionization, are the major factors limiting the achievement of very high carrier concentrations in n-type Ge. The commercially viable chemistry approach applied here enables fabrication of supersaturated and fully ionized prototypes with potential for broad applications in group-IV semiconductor technologies.

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confidence: 99%

Frustrated incomplete donor ionization in ultra-low resistivity germanium films

Senaratne

Kouvetakis

et al. 2014

Applied Physics Letters

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“…10,24) One of the most straightforward techniques to achieve the high donor concentration is in-situ doping during the epitaxial growth of Ge on Si. 7,25) However, there is a trade-off relationship between high crystalline quality and the doping concentration. 7,25) As a result, it is difficult to achieve doping concentration above 2×10 19 cm -3 without degradation of the crystal.…”

Section: Introductionmentioning

confidence: 99%

“…7,25) However, there is a trade-off relationship between high crystalline quality and the doping concentration. 7,25) As a result, it is difficult to achieve doping concentration above 2×10 19 cm -3 without degradation of the crystal. 7,25) In order to overcome this problem, several approaches are proposed such as gas 3 immersion laser doping (GILD) where a doping concentration of 5.6×10 19 cm -3 was achieved.…”

Section: Introductionmentioning

confidence: 99%

“…7,25) As a result, it is difficult to achieve doping concentration above 2×10 19 cm -3 without degradation of the crystal. 7,25) In order to overcome this problem, several approaches are proposed such as gas 3 immersion laser doping (GILD) where a doping concentration of 5.6×10 19 cm -3 was achieved. 12,26) Another promising process is delta-doping of a Ge layer with a high concentration of P by low-temperature deposition on top of high-quality Ge.…”

Section: Introductionmentioning

confidence: 99%

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Spin-on doping of germanium-on-insulator wafers for monolithic light sources on silicon

Al-Attili

Kako

Husain

et al. 2015

Jpn. J. Appl. Phys.

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High electron doping of germanium (Ge) is considered to be an important process to convertGe into an optical gain material and realize a monolithic light source integrated on a silicon chip. Spin-on doping is a method that offers the potential to achieve high doping concentrations without affecting crystalline qualities over other methods such as ion implantation and in-situ doping during material growth. However, a standard spin-on doping recipe satisfying these requirements is not yet available. In this paper we examine spin-on doping of Ge-on-insulator (GOI) wafers. Several issues were identified during the spin-on doping process and specifically the adhesion between Ge and the oxide, surface oxidation during activation, and the stress created in the layers due to annealing. In order to mitigate these problems, Ge disks were first patterned by dry etching followed by spin-on doping.Even by using this method to reduce the stress, local peeling of Ge could still be identified by optical microscope imaging. Nevertheless, most of the Ge disks remained after the removal of the glass. According to the Raman data, we could not identify broadening of the lineshape which shows a good crystalline quality, while the stress is slightly relaxed. We also determined the linear increase of the photoluminescence intensity by increasing the optical pumping power for the doped sample, which implies a direct population and recombination at the gamma valley.2

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“…In-situ phosphorous doping of epitaxial Ge layer has gained interest recently due to possibility of increasing electrically active levels without any ion implantation damage and subsequent dopant deactivation [5][6][7]. However, there is a scarcity of the results on the influence of PH3 on the growth kinetics, structural and electronic properties of Ge epilayers.…”

Section: Introductionmentioning

confidence: 99%