Impurity effects inahyphen;Si:H solar cells due to air, oxygen, nitrogen, phosphine, or monochlorosilane in the plasma

摘要

It is demonstrated that solar cells fabricated using plasmahyphen;depositedahyphen;Si:H alloys can be seriously degraded by the incorporation of certain impurities during deposition of theahyphen;Si:H materials. Nominally intrinsic layers are adversely affected by the addition to the plasma of air, N2+O2mixtures (although by neither N2nor O2separately), PH3, or SiH3Cl (monochlorosilane). For example, the conversion efficiency of Pd/phyphen;ihyphen;nsolar cells is lowered from 3.1percnt; to 1.5percnt; by the presence in the plasma of 3000 ppm air during deposition of theihyphen;layer. In this case modification of theahyphen;Si:H gaphyphen;state density owing to synergistic effects of oxygen and nitrogen in the plasma leads to a collapse of the spacehyphen;charge region and a reduction of the mgr;tgr; product for holes. The deleterious effects on device performance of phosphine and monochlorosilane are also discussed.