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OPTIMIZATION OF HIGH EFFICIENCY MULTILAYER SOLAR CELLS BASED ON III-V COMPOUNDS.

Objective

DURING THE LAST PERIOD, WE STARTED A RESEARCH AIMED AT THE IMPROVEMENT OF THE CUINSE2/ZNCDS SOLAR CELL (CIS/ZNCDS) BY USING A CIS "DOUBLE-LAYER" FILM, THAT IS, BY DEPOSITING AN IN-RICH LAYER ON TOP OF A CU-RICH LAYER.
SOLINFO is a program that aims to stimulate interest in the incorporation of passive solar energy design and energy efficiency into architectural attitudes.
DUE TO THEIR HIGH CONDUCTIVITY THE HEAVILY DOPED N-TYPE GAAS WAFERS CAN BE USED FOR MANUFACTORING HIGH-EFFICIENCY SOLAR CELL. HOWEVER, IN ORDER TO GET DEVICES (EITHER BY DIFFUSION OR EPITAXY) WITH SUPERIOR PERFORMANCES IT IS NECESSARY TO ELIMINATE STRUCTURAL MICRO AND MACRO-DEFECT FROM THE BULK CRYSTALS AS WELL AS TO IMPROVE THE ELECTRON MOBILITY AND THE HOLE DIFFUSION LENGHT. THIS STUDY WAS ADDRESSED TO ASSESS THE ROLE OF HIGH AMOUNTS OF DOPANTS (MAINLY SILICON AND SULPHUR) ON: DISLOCATION DENSITY, MICROPRECIPITATES, ELECTRON MOBILITY AND HOLE LIFETIME IN GAAS CRYSTALS GROWN BY THE LEC TECHNIQUE. SUBSTRATE CHARACTERIZATION WERE PERFORMED BY: HALL EFFECT AND C-V MEASUREMENTS, SEM (EBIC AND CATODOLUMINESCENCE) AND CHEMICAL ETCHING (MOLTEN KOH, A/B AND DSL ETCHS).

THE MAIN CONCLUSIONS ARE:
1) DISLOCATION DENSITY WAS REDUCED BY HEAVY SILICON AND SULPHUR DOPING (N > 10 TO THE POWER 18 / CM3);
2) SILICON IS ADVANTAGEOUS WITH RESPECT TO SULPHUR AS IT CAN BE INTRODUCED UP TO HIGH CONCENTRATION WITHOUT PRECIPITATION PHENOMENA;
3) SI-IN CO-DOPING IS EFFECTIVE IN DECREASING THE DISLOCATION DENSITY IN THE 10 TO THE POWER 17 - 10 TO THE POWER 13 ELECTRON / CM3 RANGE;
4) IN SI DOPED CRYSTALS A DOPING LEVEL GIVING ELECTRON CONCENTRATIONS AROUND 10 TO THE POWER 17 / CM3 IS THE MOST APPROPRIATE FROM THE POINT OF VIEW OF BOTH HOLE LIFETIME AND ELECTRON MOBILITY.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

NATIONAL RESEARCH COUNCIL OF ITALY
Address
Parco Area Delle Scienze 37/A
43010 Fontevivo
Italy