【作者】 骆瑛琳；

【导师】 刘维峰；

【作者基本信息】 大连理工大学 ， 微电子与固体电子学， 2014， 硕士

【摘要】 半导体器件的性能除了与构成器件的材料有关外,还主要受到器件表面和界面性质的影响。而光伏器件作为典型的半导体器件,其性能不仅与表面及界面处的载流子运动有关,而且与表面及界面处的光学特性也有较大关系。光伏器件表面及界面的研究对优化器件结构、提高器件效率具有重要意义。因此我们做了如下工作：针对于表面,本文采用高压氧化技术在纳米硅太阳能电池表面制备出了一层致密的钝化膜。高压氧化技术通过高压来补偿温度,在450℃且不破坏器件原型结构的情况下制备出一层质量较好的钝化层。在与未经过表面钝化处理及普通高温氧化钝化处理的样品进行了对比时,我们通过电流-电压(I-V)和量子效率等测试手段发现高压氧化表面处理技术可以有效的降低复合效应,使器件的外量子效率在波长350-700nm范围内明显提高,并把纳米硅太阳能电池的转换效率提高到12.22%。另外,我们还把高压技术应用到退火过程中。本文以InN薄膜为样品,在不同条件下对样品进行表面退火处理,并运用Kelvin探针对其表面功函数进行表征。发现不同的退火条件可以使InN薄膜表面功函数从4.8eV提高到5.2eV。针对于界面,本文分别在纳米硅衬底和平面硅衬底上制备了异质结器件,并通过对比它们之间电学性能的差异,探索了界面对器件性能的影响。在电流-电压(I-V)测试过程中我们发现具有不同界面形貌的异质结器件开路电压相差较大。为了进一步探究其原因,我们引入阻抗谱(IS)测试,并通过建立等效电路对器件进行拟合。拟合过程中我们发现不同器件参数间有着较大的不同,这一差异是由界面处的缺陷态和寄生效应引起的。为了进一步探索界面信息,我们还做了瞬态光伏谱(TPV)测试,并由此得到了不同器件的有效寿命,进一步证明了缺陷态和寄生效应对器件性能的影响。更多还原

【Abstract】 The performance of semiconductor devices is not only related to materials, but also influenced by the surface and interfacial characteristics of devices. As a typical semiconductor device, the performance of photovoltaic device is influenced by both the movement of carrier and optical properties of surface and the interface. The research on surface and interfacial characteristics of photovoltaic devices has important meaning for both optimizing structure of photovoltaic device and improving the conversion efficiency. Specific researches were done as followed:For the surface, a simple low temperature surface passivation method based on high pressure O2thermal oxidation was proposed for nano-silicon solar cells. With this method, the nanowire textured surface of the black silicon solar cells can be effectively passivated at an extremely low temperature of～450℃, under which the prototype structure of the device would not be damaged and a better performance was achieved compared with that treated with the conventional high temperature surface passivation. Then, the current-voltage (I-V) measurement and external quantum efficiencies (EQEs) measurement were applied to characterize the electrical properties of different devices. By contrast, we found that high-pressure oxidation surface treatment technology could effectively reduce the recombination effect and in the wavelength range of350～700nm, the EQEs were improved. Finally, the conversion efficiency of nano-silicon solar cells has reached12.22%. In addition, high-pressure technique was also applied to the process of annealing treatment and improved the surface properties of photovoltaic materials. Annealing studies were performed to investigate the effects of heat treatment on InN thin films by changing the annealing condition from vacuum to high pressure N2. Then, Kelvin probe technique, an effective characterization method was applied to characterize the changes of surface work function, which arranged from4.8eV to5.2eV with different treatment environments.For the interface, both planar-Si and nano-Si were used as substrates for different heterojunctions. The differences in electrical properties between heterojunctions were compared and the effects of the interface on the device performance were explored. In the process of I-V measurement, we found that there existed big differences between heterojunction devices with different interracial morphologies. In order to further explore the mechanism, impedance spectroscopy (IS) measurement was carried out and fitting process were bone by creating an equivalent circuit which corresponded to the structure of the devices. In the process of fitting, the big differences between device parameters were found, which were induced by defect states and parasitic effects at the interface of heterojunctions. Then, we carried out the transient spectrum photovoltaic (TPV) measurement and got the effective life time of devices with different interfacial morphologies, which further prove that defect states and parasitic effects at the interface had effect on performance of device.更多还原