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Characterization of
Ge Nanostructures Embedded Inside Porous Silicon for Photonics Application
(Pencirian Nanostruktur Ge Terbenam di dalam Silikon Berliang
untuk Aplikasi Fotonik)
A.F. Abd Rahim 1,2 *, M.R. Hashim1 & N.K. Ali3
1School of Physics, Universiti Sains Malaysia, 11800 Penang,
Malaysia
2Faculty of Electrical Engineering, Universiti Teknologi MARA, 13500
Permatang Pauh, Penang Malaysia
3Faculty of Electrical Engineering
Department of Electronic Engineering, Universiti Teknologi
Malaysia
81310 Skudai, Johor, Malaysia
Diserahkan: 7 Disember 2009 / Diterima: 13 Julai 2010
ABSTRACT
In this work we prepared
germanium nanostructures by means of filling the material inside porous silicon
(PS)
using conventional and cost effective technique, thermal evaporator. The PS acts
as patterned substrate. It was prepared by anodization of silicon wafer in
ethanoic hydrofluoric acid (HF). A Ge layer was then
deposited onto the PS by thermal evaporation. This was
followed by deposition of Si layer by thermal evaporation and anneal at 650οC
for 30 min. The process was completed by Ni metal deposition using thermal
evaporator followed by metal annealing of 400οC
for 10 min to form metal semiconductor metal (MSM)
photodetector. Structural analysis of the samples was performed using energy
dispersive x-ray analysis (EDX), scanning electron microscope (SEM),
X-ray diffraction (XRD) and Raman spectroscopy (RS). EDX spectrum suggests the presence of Ge inside the pores structure.
Raman spectrum showed that good crystalline structure of Ge can be produced
inside silicon pores with a phase with the diamond structure by (111), (220)
and (400) reflections. Finally current-voltage (I-V) measurement of the MSM photodetector
was carried out and showed lower dark currents compared to that of Si control
device. Interestingly the device showed enhanced current gain compared to Si
device which can be associated with the presence of Ge nanostructures in the
porous silicon
Keywords: Ge; porous;
Raman spectroscopy; silicon thermal evaporation
ABSTRAK
Di dalam kajian ini
nanostruktur Ge disediakan dengan mengisi Ge ke dalam liang Si menggunakan
kaedah konvensional dan kos efektif iaitu penyejatan haba. Si berliang
bertindak sebagai substrat yang beracuan. Si berliang disediakan melalui proses
anodisasi wafer Si di dalam larutan asid HF bersama etanol. Lapisan Ge
diendapkan di atas liang Si ini menggunakan teknik penyejatan haba. Kemudian
proses diteruskan dengan endapan lapisan Si menggunakan teknik yang sama dan
dipanaskan pada suhu 650οC selama 30 min. Proses ini
disempurnakan dengan mengendap logam Ni sebagai sesentuh menggunakan teknik
penyejatan haba dan diikuti dengan pemanasan logam sentuh pada suhu 400οC
selama 10 min bagi membina pengesan cahaya logam-separuh pengalir-logam.
Analisis struktur bahan kajian dilaksanakan menggunakan teknik EDX, SEM, XRD dan spektroskopi Raman. Spektrum EDX mencadangkan
kehadiran Ge di dalam struktur liang Si. Spektrum Raman menunjukkan struktur
hablur yang baik bagi Ge dapat dihasilkan di dalam liang Si dengan kehadiran
fasa berbentuk intan dengan pantulan pada satah (111), (200) dan (400).
Akhirnya pengukuran arus voltan untuk pengesan cahaya yang dibina menunjukkan
arus gelap yang rendah berbanding arus gelap peranti kawalan Si. Menariknya,
peranti pengesan cahaya ini menunjukkan peningkatan gandaan arus berbanding
peranti Si dan ini boleh dikaitkan dengan kehadiran struktur nano Ge di dalam
liang Si.
Kata kunci: Ge;
penyejatan haba; Si berliang; spektroskopi raman
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*Pengarang untuk
surat-menyurat; email: alhan570@ppinang.uitm.edu.my
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