Effects of minority-carrier response behavior on Ge MOS capacitor characteristics: Experimental measurements and theoretical simulations

Chao Ching Cheng*, Chao-Hsin Chien, Guang Li Luo, Yu Ting Ling, Ruey Dar Chang, Chi Kei Kei, Chien Nan Hsiao, Jun Cheng Liu, Chun Yen Chang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

In this paper, we present MEDICI simulations of the admittance-voltage properties of Ge and Si MOS devices, including analyses of substrate conductance Gsub and high-low transition frequency ftran, to explore the differences in the minority-carrier response. The Arrhenius-dependent Gsub characteristics revealed that a larger energy loss-by at least four orders of magnitude-occurs in Ge than in Si, reflecting the fast minority-carrier response rate, i.e., a higher value of ftran. We confirmed that the higher intrinsic carrier concentration in Ge, through the generation/recombination of midgap trap levels as well as the diffusion mechanism, resulted in the onset of low-frequency C-V curves in the kilohertz regime, accompanying the gate-independent inversion conductance. The experimental data obtained from Al2 O3Ge MOS capacitors were consistent with the values of Gsub and ftran obtained from MEDICI predictions and theoretical calculations. In addition, upon increasing the inversion biases, we observed shifts in the Gsub conductance peaks to low frequencies that mainly arose from the transition of minority carriers with bulk traps in the depletion layer. Meanwhile, we estimated that the bulky defects of ca. (2-4) × 1015 cm-3 exist in present-day low-doped Ge wafers.

Original languageEnglish
Pages (from-to)1118-1127
Number of pages10
JournalIEEE Transactions on Electron Devices
Volume56
Issue number5
DOIs
StatePublished - 23 Mar 2009

Keywords

  • Bulk trap
  • Germanium (Ge)
  • MEDICI simulation
  • MOS capacitor
  • Minority-carrier response
  • Substrate conductance

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