Electron and Acoustic Phonon Confinement in Ultrathin-Body Ge on Insulator

Vladimir Poborchii (1) , Wen Hsin Chang (2) , Hiroyuki Ishii (2) , Noriyuki Uchida (2) , Jesse Groenen (3) , Pavel Geshev (4) , Toshifumi Irisawa (2) , Tatsuro Maeda (2)

1 NeRI - Nanoelectronics Research Institute
2 NeRI - Nanoelectronics Research Institute
3 CEMES - Centre d'élaboration de matériaux et d'études structurales
4 Institute of Thermophysics of the Russian Academy of Sciences

Recent findings show significant enhancement of both the 488nm-excitation Raman signal and the electron mobility as ultrathin-body Ge-on-insulator (UTB GeOI) thickness (TGeOI) scaling below 13nm [1,2]. These phenomena could be attributed to a quantum size effect causing a change in the Ge energy band structure. Here, we study the characteristics of electron and acoustic phonon confinement in UTB GeOI with TGeOI = 1-20 nm. We observe electron band gap enlargement with a decrease in TGeOI and extract E1 exciton transverse effective mass value ~ 0.07 m0. Another size effect is the GeOI absorption enhancement associated with the increase in the electron density of states (DOS). For TGeOI < 5 nm, the E1(TGeOI) dependence suggests the influence of size-induced changes in the electron-phonon interaction on the E1 gap. This idea is supported by low-frequency Raman spectroscopy of GeOI confined acoustic phonons showing a significant change in acoustic phonon spectrum at TGeOI < 5 nm,

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Vladimir Poborchii, Wen Hsin Chang, Hiroyuki Ishii, Noriyuki Uchida, Jesse Groenen, et al.. Electron and Acoustic Phonon Confinement in Ultrathin-Body Ge on Insulator. International Conference on Solid State Devices and Materials, Sep 2018, Tokyo, Japan. pp.233-234. ⟨hal-01972100⟩