P型重掺杂硅薄膜及其在叠层电池隧道结中的应用

本文采用等离子体增强化学气相沉积(PECVD)方法沉积出不同掺杂浓度的硅薄膜.利用原子力显微镜(AFM),IR和Raman散射等手段对硅薄膜的微结构进行了研究.通过测试薄膜的暗电导和激活能,对硅薄膜的电学特性进行了分析.为提高隧道结的复合速率,在隧道结的N层、P层之间插入不同掺杂浓度的硅薄膜做复合层,并测试了隧道结的电流-电压特性和透光性.实验结果表明:随着掺杂气体比例R(B2H6/SiH4)的增加,硅薄膜逐渐由微晶硅转变为非晶硅,薄膜的微结构和电学特性随之改变.隧道结复合层的最佳掺杂气体比例R=0.04,在该条件下的薄膜是含有少量品粒的非晶硅.使用该复合层的隧道结具有阻抗小、接近欧姆接触、光吸收少等优点.

HEAVILY DOPED P TYPE SILICON FILMS AND ITS APPLICATION IN TUNNEL JUNCTIONS OF TANDEM SOLAR CELLS

Heavily doped P type silicon films had been deposited in a plasma-enhanced chemical vapor deposition（PECVD） system using hydrogen（H2） as a diluent gas of silane（SiH4） and diborane（B2H6） as the dopant gas at several gas phase doping ratios.The microstructure properties of the films had been investigated by AFM,IR and Raman scattering measurements.The electrical properties of the films had been investigated by room temperature dark conductivity（σd） and activation energy（Ea） measurements.A thin layer of silicon films of different gas phase doping ratio were inserted between the N layers and P layers of the tunnel junctions as recombination layers to increase the recombination rates.The current versus voltage characteristics and transparency spectra of the tunnel junctions were measured.It is shown that the silicon films transform from microcrystalline silicon to amorphous silicon when the gas phase doping ratio is increased.The microstructures and the electrical properties of the films changed accordingly.The best gas phase doping ratio of the tunnel junction recombination layer is 4% and the film deposited under that condition is amorphous silicon with a small amount of crystallites embedded in it.The tunnel junction with that recombination layer has advantages of small resistance,near ohm contact and negligible optical absorption.