铒铥共掺氧化锌薄膜近红外宽带发射及变温行为的研究

采用磁控共溅射技术制备了铒铥共掺杂氧化锌发光薄膜. 通过优化退火温度, 实现了薄膜的近红外 平坦宽带发射, 总带宽可达到~ 500 nm, 覆盖了光通信S+C+L+U 区波段. 此发射带由Er³⁺ 的1535 nm (⁴I_13/2 → ⁴I_15/2) 发射峰及Tm³⁺ 的1460 nm (³H₄ → ³F₄), 1640 nm (¹G₄ → ³F₂), 1740 nm (³F₄ → ³H₆) 发射峰组成. 研究表明: 退火温度低于800 ℃ 时, 没有观察到薄膜样品明显的光致发光现象; 随着退火温度 从800 ℃ 升高到1000 ℃, I₁₆₄₀/I₁₅₃₅ 发射峰强度比从0.2 升高到0.3, I₁₇₄₀/I₁₅₃₅ 发射峰强度比从0.5 降低 到0.4, 发射峰强度比均基本保持稳定; 当退火温度高于1000 ℃ 时, I₁₆₄₀/I₁₅₃₅ 发射峰强度比从0.3 升高到 0.6, I₁₇₄₀/I₁₅₃₅ 发射峰强度比从0.4 升高到0.8, 发射峰强度比均急剧增加. 变温行为表明: 随着温度从10 K 逐渐升高到300 K, 谱线的总带宽基本不变, 在340—360 nm 之间; Tm³⁺ 在1640 和1740 nm 处的发射峰强度 分别降低了2/3 和1/2, Er³⁺ 在1535 nm 的发射峰强度增大了1.2 倍. 这是因为随着温度的升高, 声子数目增 多, Er³⁺ 与Tm³⁺ 离子之间发生能量传递的概率不断变大, 并且在Tm³⁺ 离子之间没有发生交叉弛豫现象.     

Cu(In,Ga)Se2太阳能电池快速热退火效应

利用光致发光（PL）分析快速热退火对Cu(In,Ga)Se2 (CIGS)电池的影响,研究退火对薄膜缺陷的影响。Cu(In,Ga)Se2电池的PL谱中总共有 7个峰,即2个可见波段峰和5个红外波段峰。退火温度较低,可减少薄膜体内缺陷,提高载流子浓度,改善薄膜质量;退火温度过高,则会引起正常格点处元素扩散,元素化学计量比改变,体内缺陷增加,吸收层带隙降低,反而会对CIGS薄膜造成破坏。     

电势诱导衰退和湿热衰退P-PERC太阳能电池的修复与增效

针对P型钝化发射极背面接触(PERC)太阳能电池在服役期间受到电势衰退和湿热诱导衰退影响而引起光电转换效率降低的问题,本文通过光电注入和热退火工艺对已衰退电池进行修复并研究其增效机制。实验结果表明:在光照强度为3倍标准太阳光、电注入电流为10 A、退火温度为150 ℃、工艺50 min实验条件下,对180片已衰退电池进行修复实验,其中94.32%的已衰退电池的光电转换效率得到修复,实验后电池光电转换效率平均提升8.96%。光致发光光谱和量子效率分析表明,光电注入和热退火工艺可有效减少电池因电势诱导衰退和湿热衰退形成的内部缺陷和背表面缺陷,提升衰退电池片的光电转换效率。     

Performance improvement of CdS/Cu（In,Ga）Se2 solar cells after rapid thermal annealing

In this paper, we investigated the effect of rapid thermal annealing (RTA) on solar cell performance. An opto-electric conversion efficiency of 11.75% (Voc=0.64 V, Jsc = 25.88mA/cm2 , FF=72.08%) was obtained under AM 1.5G when the cell was annealed at 300℃ for 30s. The annealed solar cell showed an average absolute efficiency 1.5% higher than that of the as-deposited one. For the microstructure analysis and the physical phase confirmation, X-ray diffraction (XRD), Raman spectra, front surface reflection (FSR), internal quantum efficiency (IQE), and X-ray photoelectron spectroscopy (XPS) were respectively applied to distinguish the causes inducing the efficiency variation. All experimental results implied that the RTA eliminated recombination centers at the p-n junction, reduced the surface optical losses, enhanced the blue response of the CdS buffer layer, and improved the ohmic contact between Mo and Cu(In, Ga)Se2 (CIGS) layers. This leaded to the improved performance of CIGS solar cell.     

Variation of passivation behavior induced by sputtered energetic particles and thermal annealing for ITO/SiO_x/Si system

The damage on the atomic bonding and electronic state in a SiO_x(1.4-2.3 nm)/c-Si(150 μm) interface has been investigated.This occurred in the process of depositing indium tin oxide(ITO) film onto the silicon substrate by magnetron sputtering.We observe that this damage is caused by energetic particles produced in the plasma(atoms,ions,and UV light).The passivation quality and the variation on interface states of the SiO_x/c-Si system were mainly studied by using effective minority carrier lifetime(τ_(eff)) measurement as a potential evaluation.The results showed that the samples' τ_(eff)was reduced by more than 90%after ITO formation,declined from 107 μs to 5 μs.Following vacuum annealing at 200 ℃,the τ_(eff) can be restored to 30 μs.The components of Si to O bonding states at the SiO_x/c-Si interface were analyzed by x-ray photoelectron spectroscopy(XPS) coupled with depth profiling.The amorphous phase of the SiO_x layer and the "atomistic interleaving structure" at the SiO_x/c-Si interface was observed by a transmission electron microscope(TEM).The chemical configuration of the Si-O fraction within the intermediate region is the main reason for inducing the variation of Si dangling bonds(or interface states) and effective minority carrier lifetime.After an appropriate annealing,the reduction of the Si dangling bonds between SiO_x and near the c-Si surface is helpful to improve the passivation effect.