Date of Award

Spring 2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Materials Science and Engineering - (Ph.D.)

Department

Committee for the Interdisciplinary Program in Materials Science and Engineering

First Advisor

N. M. Ravindra

Second Advisor

Bhushan L. Sopori

Third Advisor

Anthony Fiory

Fourth Advisor

Tao Zhou

Fifth Advisor

Ken Keunhyuk Ahn

Abstract

Impact of the SiNx/n+-Si interface on silicon solar cell performance was investigated, where SiNx is used as a passivation layer. Significant shifts in capacitance, conductance and leakage current characteristics were observed for metal/SiN:H/n+-Si MOS capacitor when it was subjected to a constant voltage stress (CVS) of +10V at room temperature. The interface trap density (Dit) across the SiN:H/n+-Si interface increased from 6.3 x 109 to 7.5 x 109 cm-2 eV-1 after a 500-second stress whereas the n+/p junction diode remained unaffected by the stress. A direct correlation between the degradation of SiN:H/Si interface and the solar cell performance was observed. It is seen that there is a decrease in the open-circuit voltage (Voc) from 570 to 550 mV due to CVS. No significant change in short-circuit current (Isc) is observed whereas the conversion efficiency (η) decreases from 12.1 to 11.6% due to CVS. Therefore, the decrease in conversion efficiency by ~ 4.13% is due to increase in Dit after 500s stressing. CVS study on Cu/SiNx/n+ MOS capacitor both under dark and light illumination is carried out. It is observed that the degradation in solar cell parameters is more when the MOS capacitor is stressed under illumination compared to dark condition. It is also seen that there is a shift in both C-V and G-V characteristics after 5 hrs of light soaking. Thus, an increment in interface trap density (Dit) is observed after light soaking. Therefore, degradation in solar cell parameters occurs after light soaking due to increase in Dit.

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