Title :
Novel light trapping scheme for thin crystalline cells utilizing deep structures on both wafer sides [solar cells]
Author :
Jorgensen, Anders M. ; Clausen, Thomas ; Leistiko, Otto
Author_Institution :
Microelectron. Centre, Tech. Univ. Denmark, Lyngby, Denmark
fDate :
29 Sep-3 Oct 1997
Abstract :
A new light trapping structure is presented with trapping capabilities comparable to or better than those of the perpendicular grooves structure. The new structure traps a larger fraction of rays for 8-80 passes than the perpendicular grooves structure. The average path length enhancement is about 62 times the average thickness. The structure consists of deep (-200 μm) inverted pyramids on the front side and deep (-200 μm) truncated pyramids with eight sides on the back. The structure is realized in crystalline silicon by wet chemical etching using potassium hydroxide (KOH) and isopropanol (IPA). A process for creating thin solar cells with this light trapping scheme is described. The process includes only two main photolithographic steps and features a self-aligned front metallization. The process uses 250 μm wafers to create cells that on average are about 70 μm thick
Keywords :
elemental semiconductors; etching; photolithography; semiconductor device metallisation; semiconductor device testing; semiconductor doping; silicon; solar cells; 200 mum; 250 mum; 70 mum; deep inverted pyramids; deep structures; deep truncated pyramids; light trapping scheme; path length enhancement; photolithographic steps; self-aligned front metallization; thin crystalline solar cells; wet chemical etching; Charge carrier lifetime; Chemicals; Crystallization; Metallization; Microelectronics; Microwave integrated circuits; Optical scattering; Photovoltaic cells; Silicon; Wet etching;
Conference_Titel :
Photovoltaic Specialists Conference, 1997., Conference Record of the Twenty-Sixth IEEE
Conference_Location :
Anaheim, CA
Print_ISBN :
0-7803-3767-0
DOI :
10.1109/PVSC.1997.654079
