Atomic layer deposition of Al2O3 films on silicon wafers and their passivation property

• Main Authors: GUO-HUA LIAU, 廖國樺
• Other Authors: Lu-Sheng Hong
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/83771813305358570568

碩士 === 國立臺灣科技大學 === 化學工程系 === 101 === Surface passivation and anti-reflection are important issues for silicon based solar cells. In this thesis, we deposited Al2O3 passivation films on silicon wafers using atomic layer deposition (ALD) technique. First of all, self-limiting growth region for Al2O3-ALD films both by O2 plasma and H2O thermal ALD were investigated. For plasma ALD, the growth rate was limited at 1.9 nm/cycle, at a process window of 125~275℃. By contrast, the growth rate was limited at 1.1 nm/cycle for thermal ALD. After depositing 11 nm Al2O3 films at a substrate temperature of 175℃ on both sides of silicon wafer by plasma ALD followed by an annealing at 425℃in N2 atmosphere for 15min, the best effective lifetime was 2210 μs, corresponding to a surface recombination velocity of 6.3 cm/s. By applying the optimized condition to deposit 100 nm Al2O3 films on both sides of a silicon wafer with nanostructure (black-silicon), an effective lifetime of 106 μs was obtained. Poor step coverage may be ascribable to the short effective carrier lifetime.