Penumbuhan Lapisan Tipis Berbasis Silikon dengan Sistem Hot Wire PECVD (Bagian I)

LAPORAN PENELITIAN  – Lembaga Penelitian Universitas Tadulako (2006).  Laporan hasil penelitian fundamental yang berjudul penumbuhan lapisan tipis berbasis silikon dengan sistem hot wire PECVD diketua oleh Drs. Syamsu, M.Si. dengan anggota Amiruddin Kade, S.Pd., M.Si., dan Haeruddin, S.Pd., M.Si. Penelitian ini dibiayai oleh DP2M DIKTI dengan nomor kontrak: 033/SP3/PP/DP2M/2006 tanggal 1 Pebruuariu 2006.

SUMMARY-The HW-PECVD system was then applied to grow a-Si:H, μc-Si:H and poly-Si thin films on corning glass 7059 by using 10% silane (SiH4) gas diluted in hydrogen (H2) as gas source. These thin films were then characterized to investigate the optical and electrical properties, and the structure of the films using ultraviolet visible (UV-VIS) spectrometer, DEKTAK IIA, X-ray diffractometer (XRD), scanning electron microscope (SEM). The conductivity was also measured by using two points (coplanar) method. By optimization of filament temperature, a better quality a-Si:H thin films with dark conductivities is relative high (1.59x10-11 S/cm). The deposition rate and the optical band gap of the a-Si:H thin film were 0.60 Å/s and 1.98 eV. These results showed that by using HW-PECVD system, the optical properties was successfully increased without deteriorating in the electrical properties. The optical band gap and photosensitivity of μc-Si:H thin films which have been grown by optimization of rf power, decreased from 1.68 – 1.56 eV and 1.47x103 – 6.08x101, respectively with increasing in rf power from 60 – 120 watt. The decrease in the optical band gap and photosensitivity indicated that the structure has been transformed from amorphous to microcrystalline state. The films that are grown under rf power of 120 watt had microcrystalline structure with crystal orientation of <111>, <220>, <311>, and <400>. The preferential crystal orientation is <111>, with a high dark and photoconductivities of 6.84x10-5 S/cm and 4.16x10-3 S/cm, respectively. The deposition rate and the optical band gap of the μc-Si:H thin films were 1.90 Å/s and 1.56 eV. The poly-Si thin films had successfully been grown with crystal orientation of <111>, <220>, and <311>. The deposition rate of poly-Si was about 2.2 nm/s. Dark and photoconductivities of the films were 6.00x10-6 S/cm and 6.20x10-1 S/cm, respectively at  deposition pressure 300 mTorr. Finally, one can conclude that a better quality the a-Si:H, μc-Si:H, and poly-Si thin films were grown by using hot wire plasma enhanced chemical vapor deposition (HW-PECVD) system.

SARAN - Percobaan lebih lanjut pada sistem HW-PECVD bisa dilakukan dengan mengoptimasi tekanan deposisi, laju aliran gas silan dan temperatur substrat untuk penumbuhan lapisan tipis a-Si:H. Optimasi temperatur substrat masih diharapkan pada penumbuhan lapisan tipis C-Si:H. Demikian pula optimasi rasio laju aliran gas dopan dalam gas silan pada penumbuhan lapisan tipis a-Si:H, C-Si:H, dan poly-Si untuk menumbuhkan lapisan tipis tipe p dan n. Hal ini berguna untuk meningkatkan kualitas lapisan tipis berbasis silikon yang terbentuk. Dengan demikian aplikasi lapisan tipis berbasis silikon untuk devais dapat meningkatkan karakteristik sifat optik dan listriknya.