Anda belum login :: 30 Apr 2025 07:41 WIB
Home
|
Logon
Hidden
»
Administration
»
Collection Detail
Detail
Heteroepitaxy and dry oxidation of silicon-germanium and silicon-germanium-carbon alloy thin films on silicon(100)
Bibliografi
Author:
Xiang, Jiong
;
Herbots, Nicole
(Advisor)
Topik:
PHYSICS
;
CONDENSED MATTER|ENGINEERING
;
MATERIALS SCIENCE|ENGINEERING
;
ELECTRONICS AND ELECTRICAL
Bahasa:
(EN )
ISBN:
0-599-67417-2
Penerbit:
Arizona State University
Tahun Terbit:
2000
Jenis:
Theses - Dissertation
Fulltext:
9963180.pdf
(0.0B;
0 download
)
Abstract
Heteroepitaxial silicon-germanium (Si
1-x
Ge
x
) alloys have found applications in Si-based technology. However, a good quality dielectric on Si
1-x
Ge
x
cannot be obtained by thermal oxidation. The goal of this study is to investigate the effect of carbon incorporation upon epitaxial growth and thermal oxidation of Si
1-x
Ge
x
alloys and its role on strain compensation in Si
1-x
Ge
x
alloys. Both binary silicon-germanium (Si
1-x
Ge
x
) and ternary silicon-germanium-carbon (Si
1-x-y
Ge
x
C
y
) alloys with similar Si/Ge ratio are grown by Combined Ion and Molecular beam Deposition (CIMD) on P-type Si (100) substrate and compared. Prior to the epitaxial growth, a unique passivation technique is used to provide an ultra-clean and ultra-smooth Si (100) surface at low temperature. It involves a “modified RCA-type” pre-cleaning followed by HF/Methanol passivation and
in situ
thermal cleaning at a low temperature. As-deposited epitaxial films are then oxidized at three different temperatures by rapid thermal oxidation and furnace dry oxygen. The composition, structure, crystalline quality and surface morphology of binary and ternary alloys before and after oxidation are compared using a combination of Rutherford Backscattering Spectrometry (RBS) and ion channeling at 2.0 MeV, carbon Nuclear Resonance Analysis (NRA) at 4.3 MeV with
4
He
++
ions, Secondary Ion-Mass Spectrscopy (SIMS), Tapping Mode Atomic Force Microscopy (TMAFM), High-Resolution Transmission Electron Microscopy (HRTEM), and Fourier Transformation Infrared (FTIR) spectroscopy. The study demonstrates that the hydroxide passivated Si (100) surface obtained by our passivation technique yields exceptionally smooth and ordered (1x1) Si (100) surfaces at room temperature, and ultra-smooth (2x1) ordering after
in situ
low temperature desorption. We show that it is difficult to grow Si
1-x-y
Ge
x
C
y
films with quality comparable to binary Si
1-x
Ge
x
. Instead our results indicate a lower barrier to defect formation in Si
1-x-y
Ge
x
C
y
than in Si
1-x
Ge
x
. We find that a growth temperature lower than 560°C is necessary to avoid the precipitation of a precursor phase to SiC in Si and in Si
1-x
Ge
x
matrix, akin to Guinier Preston zones in the growth conditions used. The Si
1-x-y
Ge
x
C
y
films are considerably rougher than the Si
1-x
Ge
x
films of similar Si/Ge fractions. Roughness increases with increasing C fraction, indicating that the introduction of C lowers the barrier for the onset of Stranski-Krastanov type growth. The importance of an independent and accurate measurement of the total and substitutional C fraction
within
the films is shown. This study also demonstrates the importance of using a combination of different analysis techniques for film characterization. Dry oxidation of (Si
1-x
Ge
x
) and Si
1-x-y
Ge
x
C
y
thin films leads to the formation of a conformal SiO
2
layer on the top surface, while Ge segregates towards the top surface and at the SiO
2
/Si
1-x
Ge
x
and SiO
2
/Si
1-x-y
Ge
x
C
y
interfaces, in agreement with previous findings. However, we report the first time observation that dry oxidation rates in (Si
1-x
Ge
x
) decrease with increasing Ge fraction x for x > 0.20 and with increasing film minimum yield. Ion channeling analysis and strain measurements indicate that the incorporation of C rather than the amount of C itself affects the dry oxidation mechanism. Dry oxidation relaxes the previously strained (Si
1-x
Ge
x
) making the films more defective with a rougher surface. This is in contrast to the oxidation of Si (100) where oxidation always has a planarization effect. For relaxed Si
1-x
Ge
x
and defective Si
1-x-y
Ge
x
C
y
, dry oxidation does not have significant effect on the film crystalline quality and on the surface morphology.
Opini Anda
Klik untuk menuliskan opini Anda tentang koleksi ini!
Lihat Sejarah Pengadaan
Konversi Metadata
Kembali
Process time: 0.078125 second(s)
