TY - JOUR
T1 - Optical and electrical evaluations of SiGe layers on insulator fabricated using Ge condensation by dry oxidation
AU - Wang, Dong
AU - Nakashima, Hiroshi
N1 - Funding Information:
The authors thank SUMCO Corporation for providing wafers used in this study. We also thank Dr. Seiichiro Ii for the TEM measurement. This study was partially supported by a Special Coordination Fund for Promoting Science and Technology from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
PY - 2009/8
Y1 - 2009/8
N2 - Photoluminescence (PL) and dual-metal-oxide-semiconductor (dual-MOS) deep level transient spectroscopy (DLTS) evaluations were performed for SiGe layers on insulator fabricated using Ge condensation by dry oxidation. Defect generation and transformation during the temperature ramp-up process were studied by PL. Band-band transition PL peaks were clearly observed for the as-grown wafers and the peak intensities decreased with an increase in the target temperature (Tt). Defect-related PL signals were observed at around 0.82, 0.88, 0.95, and 1.0 eV, which varied according to Tt and the SiGe thickness. The dependence of defect-related PL on Tt consists with that the defect generation of misfit-dislocation and transformation to stacking-faults with increasing Tt, which was conformed by transmission electron microscopy. After Ge condensation by dry oxidation, four strained Si/SiGe on insulator (SSGOI) wafers having different Ge fractions (Ge%) and Ge condensation temperatures (Tc) were evaluated using PL and dual-MOS DLTS methods. For the sample with Ge% = 20% and Tc = 1200 °C, a broad defect-related PL signal could be observed. Other SSGOI samples showed deep-level-free PL signal in the energy range from 0.77 eV to band gap, implying high wafer qualities. At mid-gap, the interface states densities (Dit) of wafers with Ge% = 15% and 20% were approximately 5 × 1011 and 1 × 1012 cm-2 eV-1, respectively, which were higher than that of Si/buried oxide (BOX) in a Si on insulator wafer. The high Dit of SiGe/BOX was not due to interface roughness but due to the weakness of Ge-O bonds. No deep traps with concentration great than 3 × 1011 cm-3 were detected by dual-MOS DLTS measurement in the energy range of from 0.07 to 0.24 eV above the top of valence band. Based on the PL and dual-MOS DLTS evaluations, wafer quality dependences on Ge condensation parameters were discussed. One-dimensional mappings for SiGe layer crystallinity by band-band PL intensity and Dit by dual-MOS DLTS were also performed from center to edge for all the SSGOI wafers.
AB - Photoluminescence (PL) and dual-metal-oxide-semiconductor (dual-MOS) deep level transient spectroscopy (DLTS) evaluations were performed for SiGe layers on insulator fabricated using Ge condensation by dry oxidation. Defect generation and transformation during the temperature ramp-up process were studied by PL. Band-band transition PL peaks were clearly observed for the as-grown wafers and the peak intensities decreased with an increase in the target temperature (Tt). Defect-related PL signals were observed at around 0.82, 0.88, 0.95, and 1.0 eV, which varied according to Tt and the SiGe thickness. The dependence of defect-related PL on Tt consists with that the defect generation of misfit-dislocation and transformation to stacking-faults with increasing Tt, which was conformed by transmission electron microscopy. After Ge condensation by dry oxidation, four strained Si/SiGe on insulator (SSGOI) wafers having different Ge fractions (Ge%) and Ge condensation temperatures (Tc) were evaluated using PL and dual-MOS DLTS methods. For the sample with Ge% = 20% and Tc = 1200 °C, a broad defect-related PL signal could be observed. Other SSGOI samples showed deep-level-free PL signal in the energy range from 0.77 eV to band gap, implying high wafer qualities. At mid-gap, the interface states densities (Dit) of wafers with Ge% = 15% and 20% were approximately 5 × 1011 and 1 × 1012 cm-2 eV-1, respectively, which were higher than that of Si/buried oxide (BOX) in a Si on insulator wafer. The high Dit of SiGe/BOX was not due to interface roughness but due to the weakness of Ge-O bonds. No deep traps with concentration great than 3 × 1011 cm-3 were detected by dual-MOS DLTS measurement in the energy range of from 0.07 to 0.24 eV above the top of valence band. Based on the PL and dual-MOS DLTS evaluations, wafer quality dependences on Ge condensation parameters were discussed. One-dimensional mappings for SiGe layer crystallinity by band-band PL intensity and Dit by dual-MOS DLTS were also performed from center to edge for all the SSGOI wafers.
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U2 - 10.1016/j.sse.2009.04.021
DO - 10.1016/j.sse.2009.04.021
M3 - Article
AN - SCOPUS:67649233078
SN - 0038-1101
VL - 53
SP - 841
EP - 849
JO - Solid-State Electronics
JF - Solid-State Electronics
IS - 8
ER -