In situ low temperature As-doping of Ge films using As(SiH3)3 and As(GeH3)3: Fundamental properties and device prototypes

Chi Xu, J. D. Gallagher, P. M. Wallace, C. L. Senaratne, P. Sims, Jose Menendez, John Kouvetakis

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

We report the development of a new method to systematically and controllably achieve very high carrier concentrations in As-doped germanium using ultra-low temperature, high efficiency routes based on the structurally and chemically compatible inorganic hydrides As(SiH3)3 and As(GeH3)3. The Ge n-layers are grown on Ge-buffered Si(100) using in situ depositions of the compounds with Ge3H8 at 330°C. The as-grown films are found to exhibit excellent crystallinity, defect-free interfaces, atomically smooth surfaces and flat doping profiles with abrupt edges. The active carrier densities are measured to be in the range of 1 ×1019-8.4 ×1019 cm-3 irrespective of the precursor type. These carrier densities are in close agreement with atomic As concentrations measured by secondary ion mass spectrometry, indicating that the growth mechanism promotes the nearly complete substitutional incorporation of dopant atoms while suppressing the formation of non-active clusters and defects. In spite of the lower solubility of As in Ge relative to that of P, the maximum carrier concentrations obtained with As(SiH3)3 and As(GeH3)3 are roughly 30% higher than those found with the analogous P(SiH3)3 and P(GeH3)3. This result, along with the close similarity in band gap narrowing observed for the two methods, suggests that the As-doping route may be advantageous for optical devices that require the highest possible carrier concentrations to populate the conduction band valley associated with direct gap emission. On the other hand - due to the inherently shorter carrier relaxation times in As-doped Ge - the lowest observed resistivity of 5 ×10-4 Ω cm is slightly higher than the lowest resistivity from P-doped analogs. Finally, optical responsivity, electroluminescence and I-V properties of photodiodes fabricated using As(SiH3)3 and As(GeH3)3 are found to be on par with those observed from Ge-on-Si reference analogs, indicating that the chemistry approach described here represents a viable and straightforward route to doping and activation of device-quality materials.

Original languageEnglish (US)
Article number105028
JournalSemiconductor Science and Technology
Volume30
Issue number10
DOIs
StatePublished - Sep 14 2015

Fingerprint

Carrier concentration
prototypes
Doping (additives)
routes
analogs
Temperature
electrical resistivity
defects
Germanium
cryogenic temperature
Defects
electroluminescence
secondary ion mass spectrometry
hydrides
photodiodes
valleys
Electroluminescence
crystallinity
germanium
Secondary ion mass spectrometry

Keywords

  • arsenic
  • doping
  • germanium

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Condensed Matter Physics

Cite this

In situ low temperature As-doping of Ge films using As(SiH3)3 and As(GeH3)3 : Fundamental properties and device prototypes. / Xu, Chi; Gallagher, J. D.; Wallace, P. M.; Senaratne, C. L.; Sims, P.; Menendez, Jose; Kouvetakis, John.

In: Semiconductor Science and Technology, Vol. 30, No. 10, 105028, 14.09.2015.

Research output: Contribution to journalArticle

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abstract = "We report the development of a new method to systematically and controllably achieve very high carrier concentrations in As-doped germanium using ultra-low temperature, high efficiency routes based on the structurally and chemically compatible inorganic hydrides As(SiH3)3 and As(GeH3)3. The Ge n-layers are grown on Ge-buffered Si(100) using in situ depositions of the compounds with Ge3H8 at 330°C. The as-grown films are found to exhibit excellent crystallinity, defect-free interfaces, atomically smooth surfaces and flat doping profiles with abrupt edges. The active carrier densities are measured to be in the range of 1 ×1019-8.4 ×1019 cm-3 irrespective of the precursor type. These carrier densities are in close agreement with atomic As concentrations measured by secondary ion mass spectrometry, indicating that the growth mechanism promotes the nearly complete substitutional incorporation of dopant atoms while suppressing the formation of non-active clusters and defects. In spite of the lower solubility of As in Ge relative to that of P, the maximum carrier concentrations obtained with As(SiH3)3 and As(GeH3)3 are roughly 30{\%} higher than those found with the analogous P(SiH3)3 and P(GeH3)3. This result, along with the close similarity in band gap narrowing observed for the two methods, suggests that the As-doping route may be advantageous for optical devices that require the highest possible carrier concentrations to populate the conduction band valley associated with direct gap emission. On the other hand - due to the inherently shorter carrier relaxation times in As-doped Ge - the lowest observed resistivity of 5 ×10-4 Ω cm is slightly higher than the lowest resistivity from P-doped analogs. Finally, optical responsivity, electroluminescence and I-V properties of photodiodes fabricated using As(SiH3)3 and As(GeH3)3 are found to be on par with those observed from Ge-on-Si reference analogs, indicating that the chemistry approach described here represents a viable and straightforward route to doping and activation of device-quality materials.",
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AU - Wallace, P. M.

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