Restricted-access al-mediated material transport in al contacting of pureGaB Ge-on-Si p+n diodes

Amir Sammak, Lin Qi, Lis Karen Nanver

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Abstract

The effectiveness of using nanometer-thin boron (PureB) layers as interdiffusion barrier to aluminum (Al) is studied for a contacting scheme specifically developed for fabricating germanium-on-silicon (Ge-on-Si) p + n photodiodes with an oxide-covered light entrance window. Contacting is achieved at the perimeter of the Ge-island anode directly to an Al interconnect metallization. The Ge is grown in oxide windows to the Si wafer and covered by a B and gallium (Ga) layer stack (PureGaB) composed of about a nanometer of Ga for forming the p + Ge region and 10 nm of B as an interdiffusion barrier to the Al. To form contact windows, the side-wall oxide is etched away, exposing a small tip of the Ge perimeter to Al that from this point travels about 5 μm into the bulk Ge crystal. In this process, Ge and Si materials are displaced, forming Ge-filled V-grooves at the Si surface. The Al coalesces in grains. This process is studied here by high-resolution cross-sectional transmission electron microscopy and energy dispersive x-ray spectroscopy that confirm the purities of the Ge and Al grains. Diodes are fabricated with different geometries and statistical current–voltage characterization reveals a spread that can be related to across-the-wafer variations in the contact processing. The I–V behavior is characterized by low dark current, low contact resistance, and breakdown voltages that are suitable for operation in avalanching modes. The restricted access to the Ge of the Al inducing the Ge and Si material transport does not destroy the very good electrical characteristics typical of PureGaB Ge-on-Si diodes.
Original languageUndefined
Pages (from-to)4676-4683
Number of pages8
JournalJournal of electronic materials
Volume44
Issue number12
DOIs
Publication statusPublished - Dec 2015

Keywords

  • photodiodes
  • pure Ga
  • EWI-26408
  • Pure Bpure GaGe-on-SiGe diodesphotodiodesAl-induced material mediation
  • Al-induced material mediation
  • Ge-on-Si
  • Pure B
  • METIS-314998
  • IR-98248
  • Ge diodes

Cite this

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title = "Restricted-access al-mediated material transport in al contacting of pureGaB Ge-on-Si p+n diodes",
abstract = "The effectiveness of using nanometer-thin boron (PureB) layers as interdiffusion barrier to aluminum (Al) is studied for a contacting scheme specifically developed for fabricating germanium-on-silicon (Ge-on-Si) p + n photodiodes with an oxide-covered light entrance window. Contacting is achieved at the perimeter of the Ge-island anode directly to an Al interconnect metallization. The Ge is grown in oxide windows to the Si wafer and covered by a B and gallium (Ga) layer stack (PureGaB) composed of about a nanometer of Ga for forming the p + Ge region and 10 nm of B as an interdiffusion barrier to the Al. To form contact windows, the side-wall oxide is etched away, exposing a small tip of the Ge perimeter to Al that from this point travels about 5 μm into the bulk Ge crystal. In this process, Ge and Si materials are displaced, forming Ge-filled V-grooves at the Si surface. The Al coalesces in grains. This process is studied here by high-resolution cross-sectional transmission electron microscopy and energy dispersive x-ray spectroscopy that confirm the purities of the Ge and Al grains. Diodes are fabricated with different geometries and statistical current–voltage characterization reveals a spread that can be related to across-the-wafer variations in the contact processing. The I–V behavior is characterized by low dark current, low contact resistance, and breakdown voltages that are suitable for operation in avalanching modes. The restricted access to the Ge of the Al inducing the Ge and Si material transport does not destroy the very good electrical characteristics typical of PureGaB Ge-on-Si diodes.",
keywords = "photodiodes, pure Ga, EWI-26408, Pure Bpure GaGe-on-SiGe diodesphotodiodesAl-induced material mediation, Al-induced material mediation, Ge-on-Si, Pure B, METIS-314998, IR-98248, Ge diodes",
author = "Amir Sammak and Lin Qi and Nanver, {Lis Karen}",
note = "Open Access",
year = "2015",
month = "12",
doi = "10.1007/s11664-015-4008-x",
language = "Undefined",
volume = "44",
pages = "4676--4683",
journal = "Journal of electronic materials",
issn = "0361-5235",
publisher = "Springer",
number = "12",

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Restricted-access al-mediated material transport in al contacting of pureGaB Ge-on-Si p+n diodes. / Sammak, Amir; Qi, Lin; Nanver, Lis Karen.

In: Journal of electronic materials, Vol. 44, No. 12, 12.2015, p. 4676-4683.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Restricted-access al-mediated material transport in al contacting of pureGaB Ge-on-Si p+n diodes

AU - Sammak, Amir

AU - Qi, Lin

AU - Nanver, Lis Karen

N1 - Open Access

PY - 2015/12

Y1 - 2015/12

N2 - The effectiveness of using nanometer-thin boron (PureB) layers as interdiffusion barrier to aluminum (Al) is studied for a contacting scheme specifically developed for fabricating germanium-on-silicon (Ge-on-Si) p + n photodiodes with an oxide-covered light entrance window. Contacting is achieved at the perimeter of the Ge-island anode directly to an Al interconnect metallization. The Ge is grown in oxide windows to the Si wafer and covered by a B and gallium (Ga) layer stack (PureGaB) composed of about a nanometer of Ga for forming the p + Ge region and 10 nm of B as an interdiffusion barrier to the Al. To form contact windows, the side-wall oxide is etched away, exposing a small tip of the Ge perimeter to Al that from this point travels about 5 μm into the bulk Ge crystal. In this process, Ge and Si materials are displaced, forming Ge-filled V-grooves at the Si surface. The Al coalesces in grains. This process is studied here by high-resolution cross-sectional transmission electron microscopy and energy dispersive x-ray spectroscopy that confirm the purities of the Ge and Al grains. Diodes are fabricated with different geometries and statistical current–voltage characterization reveals a spread that can be related to across-the-wafer variations in the contact processing. The I–V behavior is characterized by low dark current, low contact resistance, and breakdown voltages that are suitable for operation in avalanching modes. The restricted access to the Ge of the Al inducing the Ge and Si material transport does not destroy the very good electrical characteristics typical of PureGaB Ge-on-Si diodes.

AB - The effectiveness of using nanometer-thin boron (PureB) layers as interdiffusion barrier to aluminum (Al) is studied for a contacting scheme specifically developed for fabricating germanium-on-silicon (Ge-on-Si) p + n photodiodes with an oxide-covered light entrance window. Contacting is achieved at the perimeter of the Ge-island anode directly to an Al interconnect metallization. The Ge is grown in oxide windows to the Si wafer and covered by a B and gallium (Ga) layer stack (PureGaB) composed of about a nanometer of Ga for forming the p + Ge region and 10 nm of B as an interdiffusion barrier to the Al. To form contact windows, the side-wall oxide is etched away, exposing a small tip of the Ge perimeter to Al that from this point travels about 5 μm into the bulk Ge crystal. In this process, Ge and Si materials are displaced, forming Ge-filled V-grooves at the Si surface. The Al coalesces in grains. This process is studied here by high-resolution cross-sectional transmission electron microscopy and energy dispersive x-ray spectroscopy that confirm the purities of the Ge and Al grains. Diodes are fabricated with different geometries and statistical current–voltage characterization reveals a spread that can be related to across-the-wafer variations in the contact processing. The I–V behavior is characterized by low dark current, low contact resistance, and breakdown voltages that are suitable for operation in avalanching modes. The restricted access to the Ge of the Al inducing the Ge and Si material transport does not destroy the very good electrical characteristics typical of PureGaB Ge-on-Si diodes.

KW - photodiodes

KW - pure Ga

KW - EWI-26408

KW - Pure Bpure GaGe-on-SiGe diodesphotodiodesAl-induced material mediation

KW - Al-induced material mediation

KW - Ge-on-Si

KW - Pure B

KW - METIS-314998

KW - IR-98248

KW - Ge diodes

U2 - 10.1007/s11664-015-4008-x

DO - 10.1007/s11664-015-4008-x

M3 - Article

VL - 44

SP - 4676

EP - 4683

JO - Journal of electronic materials

JF - Journal of electronic materials

SN - 0361-5235

IS - 12

ER -