原子层沉积氧化铝薄膜对多晶太阳能电池表面钝化的影响

A stack of Al2O3/SiNx dual layer was applied for the back side surface passivation of p-type multi-crystalline silicon solar cells, with laser-opened line metal contacts, forming a local aluminum back surface field （local Al-BSF） structure. A slight amount of Al2O3, wrapping around to the front side of the wafer during the thermal atomic layer deposition process, was found to have a negative influence on cell performance. The different process flow was found to lead to a different cell performance, because of the Al2O3 wrapping around the front surface. The best cell performance, with an absolute efficiency gain of about 0.6% compared with the normal full Al-BSF structure solar cell, was achieved when the Al2O3 layer was deposited after the front surface of the wafer had been covered by a SiNx layer. We discuss the possible reasons for this phenomenon, and propose three explanations as the Ag paste, being hindered from firing through the front passivation layer, degraded the SiNx passivation effect and the Al2O3 induced an inversion effect on the front surface. Characterization methods like internal quantum efficiency and contact resistance scanning were used to assist our understanding of the underlying mechanisms.     

PEALD制备的Al2O3薄膜在n-TOPCon太阳电池上的钝化性能

对采用等离子体增强原子层沉积(PEALD)法制备的Al2O3薄膜在n型单晶硅隧穿氧化层钝化接触(TOPCon)太阳电池正表面的钝化性能进行了研究.采用少数载流子寿命、X射线电子能谱(XPS)及J-V特性的测试分析,重点研究了 Al2O3沉积温度、薄膜厚度及薄膜形成后不同退火条件对钝化性能的影响,实现了低表面复合速率、良好钝化效果的产业化制备的Al2O3薄膜工艺.研究结果表明,在沉积温度为150℃、膜厚为5 nm、退火温度为450℃时,测试计算得出薄膜中O和Al的原子数之比为2.08,电池发射极正表面复合速率较低,达到了Al2O3钝化的最优效果,并且分析了 Al2O3薄膜的化学态和形成机理.利用其Al2O3薄膜工艺制备的n型单晶硅TOPCon太阳电池开路电压提升了 8 mV,电池的平均光电转换效率达到了 23.30％.     

溅射条件对Al2O3薄膜介电强度和沉积速率的影响

用射频溅射方法，在不同工作气体（纯Ａｒ和Ａｒ＋１０％Ｏ＿２）和不同基片偏压（－３０Ｖ到－１８０Ｖ，间隔－３０Ｖ）下，由烧结Ａｌ＿２Ｏ＿３靶材制备Ａｌ＿２Ｏ＿３薄膜。测试了样品的介电强度和沉积速率，对部分样品的结构和成份分别用ＸＰＳ和Ｘ射线进行了分析。结果表明：薄膜均呈非晶态；在两种工作气体中，随着基片负偏压的升高，沉积速率和介电强度均下降，但在－６０Ｖ偏压时，介电强度具有最大值。含氧的工作气体导致沉积速率下降，但提高了介电强度。在含氧和－６０Ｖ偏压下，Ａｌ＿２Ｏ＿３薄膜的平均介电强度为３．４６ＭＶ／ｃｍ。纯氩气氛中制备的Ａｌ＿２Ｏ＿３薄膜是缺氧的，而含氧的工作气体可使薄膜中的氧含量提高。     

Ga2O3缓冲层厚度对柔性衬底沉积Cu/ITO薄膜性能的影响

Cu and Cu/ITO films were prepared on polyethylene terephthalate （PET） substrates with a Ga2O3 buffer layer using radio frequency （RF） and direct current （DC） magnetron sputtering. The effect of Cu layer thickness on the optical and electrical properties of the Cu film deposited on a PET substrate with a Ga2O3 buffer layer was studied, and an appropriate Cu layer thickness of 4.2 nm was obtained. Changes in the optoelectrical properties of Cu（4.2 nm）/ITO（30 nm） films were investigated with respect to the Ga2O3 buffer layer thickness. The optical and electrical properties of the Cu/ITO films were significantly influenced by the thickness of the Ga2O3 buffer layer. A maximum transmission of 86%, sheet resistance of 45 Ω/□ and figure of merit of 3.96 × 10^-3 Ω^ -1 were achieved for Cu（4.2 nm）/ITO（30 nm） films with a Ga2O3 layer thickness of 15 nm.     

Al2O3过渡层厚度对AZO薄膜性能的影响研究

采用磁控溅射法,在预先沉积了Al2O3过渡层的玻璃衬底上制备了性能优良的AZO薄膜。借助XRD、AFM、四探针仪和分光光度计对AZO薄膜的结构、表面形貌以及电学和光学性质进行了表征,并研究了Al2O3过渡层厚度对AZO薄膜性能的影响。结果表明:Al2O3过渡层的添加对AZO薄膜的表面形貌有一定影响;AZO薄膜的结晶质量随着过渡层厚度的增加先上升后下降;AZO薄膜的电阻率因过渡层的添加而明显降低,特别是在AZO薄膜较薄时;在添加了1～3 nm厚的过渡层后,160 nm厚的AZO薄膜的电阻率下降了44%左右;AZO薄膜的可见光透射率和光学带隙基本不受过渡层影响。     

背表面形貌对硅太阳电池效率的影响

Different processes are used on the back surface of silicon wafers to form cells falling into three groups：textured, planar, and sawed-off pyramid back surface.The characteristic parameters of the cells, ISC, VOC, FF, Pm, and Eff, are measured.All these parameters of the planar back surface cells are the best.The FF, Pm, and Eff of sawed-off pyramid back surface cells are superior to textured back surface cells, although ISC and VOC are lower.The parasitic resistance is analyzed to explain the higher FF of the sawed-off pyramid back surface cells.The cross-section scanning electron microscopy（SEM） pictures show the uniformity of the aluminum-silicon alloy, which has an important effect on the back surface recombination velocity and the ohmic contact.The measured value of the aluminum back surface field thickness in the SEM picture is in good agreement with the theoretical value deduced from the Al-Si phase diagram.It is shown in an external quantum efficiency（EQE） diagram that the planar back surface has the best response to a wavelength between 440 and 1000 nm and the sawed-off back surface has a better long wavelength response.     

PECVD沉积双层SiNx对太阳电池性能的影响

提出了一种简单有效的制备双层SiNx薄膜的方法,其薄膜具有良好的减反射钝化特性。采用等离子体增强化学气相沉积(PECVD)的方法,通过控制SiH4和NH3气体流量比,在p型多晶硅衬底上生长单层及双层SiNx膜。随后使用薄膜测试分析仪测量了薄膜的厚度、折射率及反射率,并用Semilab WT-2000测量少数载流子寿命,通过测量量子效率,对单、双层膜电池进行了比较。实验结果表明:相比单层减反射钝化膜,采用双层SiNx膜,少数载流子寿命可以得到更好的改善,开路电压可提高约2 mV,短路电流可提高约40 mA,电池效率能提高0.15%。     

硅系太阳电池表面钝化技术比较

通过对硅片的少数载流子有效寿命、硅太阳电池的反射损失和光谱响应这三个方面的研究,比较了目前主要的硅太阳电池表面钝化技术,对这些钝化技术的优缺点进行了分析和评价.从上述三个方面的比较可以看出,RTO/SiNx堆叠钝化技术在提高硅太阳电池性能上是最优的,具有良好的应用前景.     

电子束辐照下的石墨烯上的原子层沉积Al2O3介质层

为了研究石墨烯与高k介质的结合,使用原子层沉积氧化铝在石墨衬底上。沉积前使用电子束辐照,观测到了氧化铝明显改善的形貌。归因于电子束辐照过程中的石墨层的无定形变化过程。     

PC1D方法对铝背场钝化技术的分析

降低单晶硅原材料成本,采用更薄的硅片作为太阳电池的原料是晶体硅太阳电池产业发展的趋势之一。对薄片化的太阳电池,铝背场的背表面钝化工艺显得愈加重要。采用PC1D太阳电池软件模拟的方法,对以商业用p型硅为衬底的单晶硅125×125太阳电池的铝背场的背表面钝化技术进行了模拟,分析得出,对一定厚度的电池片来说,尤其是当少数载流...     

利用二次阳极氧化方法降低N型碲镉汞材料表面复合速度

利用微波反射光电导衰退法比较了采用一次阳极氧化和二次阳极氧化的N型碲镉汞材料的非平衡载流子寿命及其随温度的变化,通过与理论值进行比较拟合得到了碲镉汞材料表面复合速度随温度的变化曲线.结果发现,二次阳极氧化方法能够更好地降低材料表面悬挂键的密度,同时减少抛光引入的表面缺陷能级的数量,从而降低材料的表面复合速度,改善材料的非平衡载流子寿命,利于制造出高性能的HgCdTe红外探测器.     

Drain current enhancement and negligible current collapse in GaN MOSFETs with atomic-layer-deposited HfO2 as a gate dielectric

Accumulation-type GaN metal-oxide-semiconductor field-effect-transistors (MOSFET’s) with atomic-layer-deposited HfO₂ gate dielectrics have been fabricated; a 4 μm gate-length device with a gate dielectric of 14.8 nm in thickness (an equivalent SiO₂ thickness of 3.8 nm) gave a drain current of 230 mA/mm and a broad maximum transconductance of 31 mS/mm. Owing to a low interfacial density of states (D_it) at the HfO₂/GaN interface, more than two third of the drain currents come from accumulation, in contrast to those of Schottky-gate GaN devices. The device also showed negligible current collapse in a wide range of bias voltages, again due to the low D_it, which effectively passivate the surface states located in the gate-drain access region. Moreover, the device demonstrated a larger forward gate bias of +6 V with a much lower gate leakage current.     

Ultra Thin Film Encapsulation of Organic Light Emitting Diode on a Plastic Substrate

We have carried out the fabrications of a barrier layer on a polyethersulfon (PES) film and organic light emitting diode (OLED) based on a plastic substrate by means of atomic layer deposition (ALD). Simultaneous deposition of 30 nm AlO_x film on both sides of the PES film gave a water vapor transition rate (WVTR) of 0.062 g/m²/day (@38°C, 100% R.H.). Further, the double layer of 200 nm SiNx film deposited by plasma enhanced chemical vapor deposition (PECVD) and 20 nm AlOx film by ALD resulted in a WVTR value lower than the detection limit of MOCON. We have investigated the OLED encapsulation performance of the double layer using the OLED structure of ITO / MTDATA (20 nm) / NPD (40 nm) / AlQ (60 nm) / LiF (1 nm) / Al (75 nm) on a plastic substrate. The preliminary life time to reach 91% of the initial luminance (1300 cd/m²) was 260 hours for the OLED encapsulated with 100 nm of PECVD‐deposited SiNx and 30 nm of ALD‐deposited AlO_x.