Structural and Electrical Properties of Polysilicon Films Prepared by AIC Process for a Polycrystalline Silicon Solar Cell Seed Layer

Abstract

Polycrystalline silicon (pc-Si) films are produced by aluminum-induced crystallization (AIC) process for a polycrystalline silicon solar cell seed layer, and the structural and electrical properties of the films are analyzed. The used structure is glass/Al/ Al<sub >2</sub>O<sub >3</sub>/a-Si, and the thickness of Al<sub >2</sub>O<sub >3</sub> layer was varied from 2&#x2009;nm to 20&#x2009;nm to investigate the influence of the Al<sub >2</sub>O<sub >3</sub> layer thickness on the formation of the polycrystalline silicon. The annealing temperature and annealing time were fixed to <svg style="vertical-align:-0.17555pt;width:28.025px;" id="M1" height="11.0375" version="1.1" viewBox="0 0 28.025 11.0375" width="28.025" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0375)"> <g transform="translate(72,-63.17)"> <text transform="matrix(1,0,0,-1,-71.95,63.39)"> <tspan style="font-size: 12.50px; " x="0" y="0">4</tspan> <tspan style="font-size: 12.50px; " x="6.2515001" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="12.503" y="0">0</tspan> </text> <text transform="matrix(1,0,0,-1,-53.2,68.56)"> <tspan style="font-size: 8.75px; " x="0" y="0">∘</tspan> </text> </g> </g> </svg>C and 5 hours, respectively, for the AIC process conditions. As a result, it is observed that the average grain size of the pc-Si films is rapidly smaller with increasing the thickness of Al<sub >2</sub>O<sub >3</sub> layer, whereas the film quality, as defects and Hall mobility, was gradually degraded with only small difference. We obtained the maximum average grain size of 15&#x2009;<i >&#x3bc;</i>m for the pc-Si film with the thickness of Al<sub >2</sub>O<sub >3</sub> layer of 4&#x2009;nm. The best resistivity and the Hall mobility was <svg style="vertical-align:-0.3135pt;width:65.824997px;" id="M2" height="14.375" version="1.1" viewBox="0 0 65.824997 14.375" width="65.824997" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,14.375)"> <g transform="translate(72,-60.5)"> <text transform="matrix(1,0,0,-1,-71.95,60.86)"> <tspan style="font-size: 12.50px; " x="0" y="0">6</tspan> <tspan style="font-size: 12.50px; " x="6.2515001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="9.3772497" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="18.404415" y="0">×</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="35.433502" y="0">0</tspan> </text> <text transform="matrix(1,0,0,-1,-30.26,66.03)"> <tspan style="font-size: 8.75px; " x="0" y="0">−</tspan> <tspan style="font-size: 8.75px; " x="5.99512" y="0">2</tspan> </text> </g> </g> </svg>&#x2009;<svg style="vertical-align:-0.12538pt;width:42.262501px;" id="M3" height="10.85" version="1.1" viewBox="0 0 42.262501 10.85" width="42.262501" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,10.85)"> <g transform="translate(72,-63.32)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">Ω</tspan> <tspan style="font-size: 12.50px; " x="12.077898" y="0">⋅</tspan> <tspan style="font-size: 12.50px; " x="18.429422" y="0">c</tspan> <tspan style="font-size: 12.50px; " x="23.980755" y="0">m</tspan> </text> </g> </g> </svg> and 90.91&#x2009;cm<sup >2</sup>/Vs, respectively, in the case of 8&#x2009;nm thick Al oxide layer.