Activation and diffusion studies of ion-implanted p and n dopants in germanium

Chui, Chi On; Gopalakrishnan, Kailash; Griffin, P.B.; Plummer, J.D.; Saraswat, Krishna C.

doi:10.1063/1.1618382

Cited by 286 publications

(189 citation statements)

References 9 publications

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“…n-type dopants in germanium have proven to be problematic, and are now a key bottleneck in the realization of advanced n-type MOS ͑NMOS͒ device performance and scaling. 5 In short, phosphorus ͑P͒ and arsenic ͑As͒ are relatively difficult to activate and diffuse quickly, [6][7][8][9] leading to high resistances and limited capability to reduce the device dimensions.…”

mentioning

confidence: 99%

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization

Duffy

Shayesteh

White

et al. 2010

Applied Physics Letters

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Design and optimization of n-type doped regions in germanium by solid phase epitaxial recrystallization (SPER) have been studied by the authors. A systematic study is presented of process variables that influence activation and thermal stability, including preamorphization, coimplants, recrystallization temperature, and postrecrystallization thermal treatments. Unlike silicon, activation after recrystallization in germanium is not optimum where the postrecrystallization thermal budget is kept to a minimum. With the aid of modeling, a maximum peak activation of 7 X 10(19) cm(-3) was extracted. A steady increase in sheet resistance during postrecrystallization anneals confirms the formation of metastable activation by SPER. It is predicted that active concentrations of 6-8 X 10(19) cm(-3) are sufficient to meet targets for sub-20 nm technologies. (C) 2010 American Institute of Physics. (doi: 10.1063/1.3452345

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mentioning

confidence: 99%

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization

Duffy

Shayesteh

White

et al. 2010

Applied Physics Letters

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“…The solid solubility of B in Ge is considerably lower than that of Ga, 21,22 and in our experiments, PureB alone did not give a satisfactory result, whereas adding PureGa did. On its own, the PureGa is very unstable.…”

Section: Methodsmentioning

confidence: 42%

Restricted-Access Al-Mediated Material Transport in Al Contacting of PureGaB Ge-on-Si p + n Diodes

Sammak

Nanver

2015

Journal of Elec Materi

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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 lm 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.

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“…Here, the As profile is significantly different from that formed by ion implantation. 25) According to a previous report 25) on the profiles of dopants introduced by ion implantation, those of P and As are not markedly different in terms of the steep dopant profile. The significant difference in As profile between the present solid-phase diffusion and I=I is attributable to the enhanced diffusion of As and the strong As concentration dependence of the diffusion constant caused by defects induced by ion implantation, as described above.…”

Section: Resultsmentioning

confidence: 99%

“…The direction of ion beams was tilted 7°off the direction normal to the substrate surface to minimize channeling. 25) RTA was carried out at 400°C for 5 min in N 2 ambient to activate B ions implanted into Ge. After removing SiO 2 , 100-nm-thick SiO 2 films were sputtered with the ECR system again and diffusion windows were opened by dipping in BHF.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Actually, a previous study has shown that the diffusion coefficients of implanted P and As in Ge are proportional to the square of the concentration of each dopant, similarly to that of Zn in InGaAs, while that of Sb in Ge is proportional to its concentration. 25) It is expected from these results that the P and As diffusion process from SOG into Ge will provide source junctions with steep impurity profiles and low defect densities. The solid-phase diffusion of n-type dopants from SOG into Ge has already been reported by several research groups.…”

Section: Introductionmentioning

confidence: 99%

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Ge p-channel tunneling FETs with steep phosphorus profile source junctions

Takaguchi

Matsumura

Katoh

et al. 2018

Jpn. J. Appl. Phys.

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The solid-phase diffusion processes of three n-type dopants, i.e., phosphorus (P), arsenic (As), and antimony (Sb), from spin-on-glass (SOG) into Ge are compared. We show that P diffusion can realize both the highest impurity concentration (>7 ' 10 19 cm %3 ) and the steepest impurity profile (>10 nm/dec) among the cases of the three n-type dopants because the diffusion coefficient is strongly dependent on the dopant concentration. As a result, we can conclude that P is the most suitable dopant for the source formation of Ge p-channel TFETs. Using this P diffusion, we fabricate Ge p-channel TFETs with high-P-concentration and steep-P-profile source junctions and demonstrate their operation. A high ON current of >1.7 µA/µm is obtained at room temperature. However, the subthreshold swing and ON current/OFF current ratio are degraded by any generation-recombination-related current component. At 150 K, SS min of >108 mV/dec and ON/OFF ratio of >3.5 ' 10 5 are obtained.

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Activation and diffusion studies of ion-implanted p and n dopants in germanium

Cited by 286 publications

References 9 publications

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization

Restricted-Access Al-Mediated Material Transport in Al Contacting of PureGaB Ge-on-Si p + n Diodes

Ge p-channel tunneling FETs with steep phosphorus profile source junctions

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