Towards monolithic integration of germanium light sources on silicon chips

Saito, Shinichi; Al-Attili, Abdelrahman; Oda, Katsuya; Ishikawa, Yasuhiko

doi:10.1088/0268-1242/31/4/043002

Cited by 57 publications

(48 citation statements)

References 208 publications

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“…Intrinsic bulk Ge is an indirect band-gap material, but it can be converted to a quasi-direct band gap material due to the small separation between the  and L valley (136 meV) [1]. It was shown that the direct band gap of Ge can be realized by tensile strain engineering, alloying with Sn or ultra-high n-type doping [2][3][4][5]. By using only one of these methods it is extremely difficult to achieve a direct band gap.…”

Section: Introductionmentioning

confidence: 99%

Strain and Band-Gap Engineering in Ge - Sn Alloys via P Doping

et al. 2018

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Ge with a quasi-direct band gap can be realized by strain engineering, alloying with Sn or ultra-high n-type doping. In this paper, we use all three approaches together -strain engineering, Sn alloying and n-type doping to fabricate direct band gap GeSn alloys. The heavily-doped n-type GeSn was realized using a CMOS-compatible non-equilibrium material processing. P is used to form a highly-doped n-type GeSn layers and to modify the lattice parameter of GeSn:P alloys. The strain engineering in heavily P-doped GeSn films is confirmed by X-ray diffraction and micro-Raman spectroscopy. The change of the band gap in GeSn:P alloy as a function of P concentration is theoretically predicted using density functional theory and experimentally verified by near-infrared spectroscopic ellipsometry.According to the shift of the absorption edge it is shown that for an electron concentration above 1×10 20 cm -3 the band gap renormalization is partially compensated by the Burstein-Moss effect. These results indicate that Ge-based materials have a large potential for the nearinfrared optoelectronic devices, fully compatible with CMOS technology.

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Section: Introductionmentioning

confidence: 99%

Strain and Band-Gap Engineering in Ge - Sn Alloys via P Doping

et al. 2018

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“…Figures 2(n) and 2(o) respectively show the corresponding calculated Ge 2 3 Λ 1c (A 1 ) and 2 3 ∆ 1c (A 1 ) character of the Ge 53 C 1 K = 0 CB eigenstates. The Ge Γ 2 c , 2 3 Λ 1c (A 1 ) and 2 3 ∆ 1c (A 1 ) character of the CB edge eigenstate is highlighted in Figs. 2(m) -2(o) using green, red and blue coloring, respectively.…”

Section: Resultsmentioning

confidence: 97%

Electronic structure evolution in dilute carbide Ge1−xCx alloys and implications for device applications

Broderick

Dunne

Tanner

et al. 2019

Journal of Applied Physics

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We present a theoretical analysis of electronic structure evolution in the highly-mismatched dilute carbide group-IV alloy Ge1−xCx. For ordered alloy supercells, we demonstrate that C incorporation strongly perturbs the conduction band (CB) structure by driving hybridisation of A1-symmetric linear combinations of Ge states lying close in energy to the CB edge. This leads, in the ultradilute limit, to the alloy CB edge being formed primarily of an A1-symmetric linear combination of the L-point CB edge states of the Ge host matrix semiconductor. Our calculations describe the emergence of a "quasi-direct" alloy band gap, which retains a significant admixture of indirect Ge L-point CB edge character. We then analyse the evolution of the electronic structure of realistic (large, disordered) Ge1−xCx alloy supercells for C compositions up to x = 2%. We show that short-range alloy disorder introduces a distribution of localised states at energies below the Ge CB edge, with these states acquiring minimal direct (Γ) character. Our calculations demonstrate strong intrinsic inhomogeneous energy broadening of the CB edge Bloch character, driven by hybridisation between Ge host matrix and C-related localised states. The trends identified by our calculations are markedly different to those expected based on a recently proposed interpretation of the CB structure based on the band anti-crossing model. The implications of our findings for device applications are discussed.

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“…Второе направление имеет неоспоримое преимущество простоты интеграции создаваемых источников излучения с элементами кремниевой интегральной наноэлектроники, однако имеет и существенный недостаток, связанный с низкой эффективностью излучательной рекомбинации носителей заряда в гетероструктурах на основе непрямозонных материалов IV группы. Для повышения эффективности излучательной рекомбинации в этих материалах в литературе рассматривались различные стратегии (см., например, обзоры [1,2]), одной из которых является модификация зонной структуры Ge. Несмотря на то что Ge является непрямозонным полупроводником (абсолютный минимум зоны проводимости находится в точке L зоны Бриллюэна), при 300 K ширина прямой запре-щенной зоны (E dir g = 0.8 эВ) лишь на ∼ 140 мэВ больше, чем непрямой (E ind g = 0.66 эВ).…”

Section: Introductionunclassified

Влияние условий роста и уровня легирования на кинетику люминесценции слоев Ge : Sb, выращенных на кремнии

Юрасов¹,

Байдакова²,

Яблонский³

et al. 2020

Физика И Техника Полупроводников

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Light-emitting properties of Ge-on-Si(001) layers doped by Sb were studied by stationary and time-resolved photoluminescence (PL) at room temperature. It was obtained that the PL intensity of n-Ge/Si(001) structures is maximized when the doping level is close to the equilibrium solubility of Sb in Ge (~1019 cm-3) which is in accordance with the previously published data. Time-resolved studies of the direct-related PL signal have shown that both the donor density and the growth conditions of doped layer, in particular, the growth temperature influence the PL kinetics. It was obtained that the increase of doping level leads to the decrease of the characteristic carrier lifetime. Moreover, usage of low growth temperatures which is needed to form the doped n-Ge layers also results in shortening of the carrier lifetime as compared with Ge layers grown at high temperatures. It was found that rapid thermal anneal at proper conditions could partially compensate the above mentioned detrimental effects and lead to the increase of both the PL intensity and carrier lifetime.

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Towards monolithic integration of germanium light sources on silicon chips

Cited by 57 publications

References 208 publications

Strain and Band-Gap Engineering in Ge - Sn Alloys via P Doping

Strain and Band-Gap Engineering in Ge - Sn Alloys via P Doping

Electronic structure evolution in dilute carbide Ge1−xCx alloys and implications for device applications

Влияние условий роста и уровня легирования на кинетику люминесценции слоев Ge : Sb, выращенных на кремнии

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