Pulse number controlled laser annealing for GeSn on insulator structure with high substitutional Sn concentration

Kenta Moto, Ryo Matsumura, Taizoh Sadoh, Hiroshi Ikenoue, Masanobu Miyao

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Abstract

Crystalline GeSn-on-insulator structures with high Sn concentration (>8%), which exceeds thermal equilibrium solid-solubility (∼2%) of Sn in Ge, are essential to achieve high-speed thin film transistors and high-efficiency optical devices. We investigate non-thermal equilibrium growth of Ge1-xSnx (0 ≤ x ≤ 0.2) on quartz substrates by using pulsed laser annealing (PLA). The window of laser fluence enabling complete crystallization without film ablation is drastically expanded (∼5 times) by Sn doping above 5% into Ge. Substitutional Sn concentration in grown layers is found to be increased with decreasing irradiation pulse number. This phenomenon can be explained on the basis of significant thermal non-equilibrium growth achieved by higher cooling rate after PLA with a lower pulse number. As a result, GeSn crystals with substitutional Sn concentration of ∼12% are realized at pulse irradiation of single shot for the samples with the initial Sn concentration of 15%. Raman spectroscopy and electron microscopy measurements reveal the high quality of the grown layer. This technique will be useful to fabricate high-speed thin film transistors and high-efficiency optical devices on insulating substrates.

Original languageEnglish
Article number262105
JournalApplied Physics Letters
Volume108
Issue number26
DOIs
Publication statusPublished - Jun 27 2016

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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