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RESEARCH ON NARROW BAND GAP ALLOYS FOR THE IMPROVEMENT OF THE EFFICIENCY OF AMORPHOUS SILICON BASED SOLAR CELLS

Objective



INFRARED ABSORPTION AND THE DENSITY OF GAP STATES HAVE BEEN MEASURED OF SAMPLES OF THIN FILMS OF AMORPHOUS SILICON FABRICATED WITH DIFFERENT GROWTH RATES IN A PLASMA OF PURE SILANE AS WELL AS IN A PLASMA DILUTED WITH 55% HYDROGEN. FOR SAMPLES GROWN IN PURE SILANE THE DENSITY OF GAP STATES AND THE INFRARED ABSORPTION AT 2070 CM-1 INCREASE WITH INCREASING GROWTH RATES. INCREASE OF THESE QUANTITIES WITH INCREASING GROWTH RATE IS NOT PRESENT IN SAMPLES GROWN IN THE DILUTED PLASMA. FROM THESE DATA IT IS CONCLUDED THAT THE MICROSTRUCTURE OF THE GROWN LAYERS DETERMINES ITS ELECTRICAL QUALITY.
THE REFRACTIVE INDEX OF A 5000 ANGSTROM THICK MICRO-CRYSTALLINE SILICON LAYER ON GLASS HAS BEEN DETERMINED FROM REFLECTION AND TRANSMISSION OF MONOCHROMATIC LIGHT VERSUS WAVE LENGTH. THESE MEASUREMENTS WERE CARRIED OUT WITH LIGHT INCIDENT AT THE GLASS SUBSTRATE AND COMPARED WITH THOSE WHEN THE LIGHT IS INCIDENT AT THE MICRO-CRYSTALLINE LAYER. THE DIFFERENCE BETWEEN THE TWO MEASUREMENTS CAN BE EXPLAINED BY A 200 ANGSTROM THICK AMORPHOUS LAYER BETWEEN THE SUBSTRATE AND THE MICRO-CRYSTALLINE LAYER.
PARALLEL TO THESE EXPERIMENTS THE COMPUTER MODEL FOR THE SIMULATION OF DEVICES, INCLUDING SOLAR CELLS, HAS BEEN EXTENDED BY SURFACE RECOMBINATION AND AUGER RECOMBINATION. CURRENT-VOLTAGE DEPENDENCIES AND ELECTRICAL FIELD DISTRIBUTIONS OF P-I-N SOLAR CELLS AND P-I-P SANDWICH STRUCTURE HAVE BEEN CALCULATED.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

TECHNISCHE UNIVERSITEIT DELFT
Address
Julianalaan 134
2628 BL Delft
Netherlands