以電子迴旋共振化學氣相沉積微晶矽薄膜太陽能電池之特性分析

Study of µc-Si:H films and fabrication of µc-Si:H p-i-n solar cell by ECRCVD

邱崇閔(Chung-Min Chiu)

指導教授 ： 黃惠良 ； 裴靜偉

國立清華大學/電機資訊學院/積體電路設計產業研發碩士專班/碩士(2007年)

摘要

本論文主旨在討論低溫微晶矽薄膜於二氧化矽及玻璃基板上之成長，利用電子迴旋共振化學氣相沉積(ECR-CVD)系統以氫稀釋法來成長多晶矽薄膜，並利用拉曼(Raman)散射頻譜則用於分析微晶矽薄膜之結晶度與結晶態體積含量，X-ray 繞射頻譜則用於分析微晶矽薄膜之擇優取向 (Preferred orientations)，紅外線吸收頻譜可分析微晶矽薄膜的氫-矽之鍵結組態及薄膜中的氫含量、導電度分析用來解析微晶矽薄膜之導電特性，而Nanospac及α-STEP測厚儀用來量測薄膜厚度，掃描式電子顯微鏡(SEM)做表面晶粒型態分析，展組量測儀(SRP)及四點探針用來量測參雜濃度等特性進行分析。
在實驗過程中我們固定上中下磁場電流分別為170/170/30安培、控制基板溫度在(250~400℃)範圍、微波功率為1200~1400瓦特，壓力為10X10-3托~40X10-3 ，改變氫稀釋比例進行薄膜分析。此外，我們也在矽薄膜中摻雜B2H6及PH3氣體形成P型及N型矽薄膜並利用四點探針及SRP對其電阻率進行量測分析。
實驗結果顯示，我們得到微晶矽薄膜的結晶態體積含量達94.5%，當氫稀釋比在95%時最大的晶粒尺寸大約是700 Ǻ，非摻雜型多晶矽薄膜的擇優取向為<110>，氫含量也隨著氫稀釋比增加而減少。在摻雜方面，N-type濃度在1.04e18cm-3，P-type濃度在1.56e18cm-3。

關鍵字

電子迴旋共振 ； 微晶矽薄膜 ； 薄膜太陽電池

並列摘要

This thesis presents the characteristics of low temperature microcrystalline silicon (µc-Si) films deposition on SiO2 and glass substrates and the solar cell fabricated by this films. We deposited the µc-Si films by electron cyclotron resonance chemical vapor deposition (ECR-CVD).
The Characterization of µc-Si films were carried out by using Raman scattering, XRD, FTIR, Nanospac, SEM, SRP, α-STEP, and Four point probe. Raman scattering spectra were used to investigate their crystallinity and the crystalline fraction in the µc-Si films. X-ray diffraction pattern (XRD) spectra were used to analyze the preferred orientation of the µc-Si films. Fourier transform infrared (FTIR) absorption spectra were used to study the silicon-hydrogen bonding configurations and the hydrogen content of the µc-Si films. Conductivity measurements were employed to study the electrical properties of µc-Si films. Nanospac and α-STEP were used to measure films thickness. Scanning electron microscopy (SEM) were used to analyze grain geometry and top morphology. Spreading Resistance Profiling (SRP) and Four point probe were used to analyze the doping concentration and resistivity.
In our experiments, the growth conditions to prepare the p, i, and n layers of solar cells by using ECRCVD were found. The experimental parameters used in this study are the Top/ Middle/ Bottom magnetic current at 170, 170 and 30A respectively and substrate temperature at 250 oC (for undoped films) ~ 400 oC (for doped films), the range of microwave power at 1200W ~ 1400W, the range of the process pressure at 10mtorr ~ 40mtorr. The hydrogen dilution ratio was varied to analyze the characteristics of thin films. In addition, we also doped the films using phosphine (PH3) and diborance(B2H6) to form the n-type and p-type silicon thin film.
The experimented results show that, the maximum crystalline fraction obtained was about 94.5%, and the largest grain size in these µc-Si films have dimension of about 700 Ǻ when the hydrogen dilution ratio was 95%. The preferred orientation of the µc-Si films were found to be <110>, and also it was observed that the hydrogen content decreased with the increase of hydrogen dilution ratio. The doped concentration of N-type is about 1.04e18cm-3 , P-type is about 1.56e18cm-3.

並列關鍵字

Thin films solar cell ； microcrystalline silicon

參考文獻

[1] Dr.J.K.Rath“Thin film silicon based solar cells and

[2] P. Maycock, PV News, Feb. 1998.

microcrystalline silicon solar cells,” in Modeling,

Sol. Energy Materials and Sol. Cells, vol. 53, pp. 189–

203, 1998.