EFFECT OF GROOVING - BASED REAR BURIED CONTACTS ON POLYCRYSTALLINE SILICON SOLAR CELLS PERFORMANCES

摘要

In This paper we investigate the effect of rear buried contacts (RBC) on the internal quantum efficiency of polycrystalline silicon (pc-Si) solar cells. To achieve the rear buried contacts (RBC), we formed grooves on the rear surface of pc-Si wafers by a new method which we called Chemical Vapor Etching (CVE). The CVE technique consists of exposing pc-Si wafers to a mixture of HF/HNO3 acids vapors. By choosing adequate antiacid masks, the CVE method let us have a sufficient groove resolution to introduce buried contacts in a simple polycrystalline silicon solar cells technology. The RBCs are realized on the base of the pc-Si solar cells using patterned grooves. The depth of the grooves is an important parameter that affects the effective thickness of the base of the solar cells and thus the internal quantum efficiency. After achieving RBCs, we observe a non negligible increase of the internal quantum efficiency (IQE), particularly in the long wavelength range. The improvement of the IQE was attributed to an enlargement of the rear ohmic contact and to the reduction of the effective thickness of the base of the cells. Adjustment of theoretical internal quantum efficiencies to experimental ones shows an enhancement of the minority carrier diffusion length (I.e., electrons in the p-type base).