GaNAs基超晶格太阳电池的分子束外延生长与器件特性

采用分子束外延(MBE)生长技术生长了周期厚度不同的1 e V吸收带边的Ga N0.03As0.97/In0.09Ga0.91As应变补偿短周期超晶格(SPSL)。高分辨率X射线衍射(HRXRD)测量结果显示,当周期厚度从6 nm增加到20 nm时,超晶格的结晶质量明显改善。然而,当周期厚度继续增加时,超晶格品质劣化。对超晶格周期良好的样品通过退火优化,获得了具有低温光致发光现象的高含N量Ga NAs/In Ga As超晶格,吸收带边位于1 e V附近。使用10个周期的Ga NAs/In Ga As超晶格(10 nm/10 nm)和Ga As组成的p-i-n太阳电池的短路电流达到10.23 m A/cm2。经聚光测试获得的饱和电流密度、二极管理想因子与由电池暗态电流-电压曲线得到的结果一致。     

Crystalline silicon surface passivation investigated by thermal atomic-layer-deposited aluminum oxide

Atomic-layer-deposited(ALD) aluminum oxide(Al_2O_3) has demonstrated an excellent surface passivation for crystalline silicon(c-Si) surfaces, as well as for highly boron-doped c-Si surfaces. In this paper, water-based thermal atomic layer deposition of Al_2O_3 films are fabricated for c-Si surface passivation. The influence of deposition conditions on the passivation quality is investigated. The results show that the excellent passivation on n-type c-Si can be achieved at a low thermal budget of 250℃ given a gas pressure of 0.15 Torr. The thickness-dependence of surface passivation indicates that the effective minority carrier lifetime increases drastically when the thickness of Al_2O_3 is larger than 10 nm. The influence of thermal post annealing treatments is also studied. Comparable carrier lifetime is achieved when Al_2O_3 sample is annealed for 15 min in forming gas in a temperature range from 400℃ to 450℃. In addition, the passivation quality can be further improved when a thin PECVD-SiN_x cap layer is prepared on Al_2O_3, and an effective minority carrier lifetime of2.8 ms and implied Voc of 721 mV are obtained. In addition, several novel methods are proposed to restrain blistering.