DETERMINATION OF DIFUSION LENGTH IN SINGLE CRYSTAL SILICON FOR SOLAR CELLS

N. DI LALLA; A. LAMAGNA; A. BOSELLI

Bs As

Workshop; WORKSHOP ON MATERIAL SCIENCE AND PHYSICS OF NON-CONVENTIONAL ENERGY SOURCES.; 1992

CNEA

Recombination of excess carriers is an important property of semiconductors materials, and characterized by the minority-carrier diffusion length ( Ld). Determination of recombination properties is of great interest, not only in field of material research, but also for device-oriented material characterization because recombination determines the electrical performance of many semiconductor device,  as the efficiency of solar cells. This paper presents a method for measuring minority carrier diffusion length using lector-beam-induced-current ( EBIC), on boron doped Cz-silicon grown in our laboratory. An aluminium Schottky barrier was elaborated on the silicon sample and then it was mounted at the electron microprobe. The diffusion length was foun from the study of the EBIC decay when the beam is slowly moved away from the diode edge. The diffusion length is evaluated for several wafers of the same ingot. The problems found surface preparation, relative with the aluminium barrier and the gold ohmic contact are described. All the LD values measured were about 60 micrones.