Fabrication of solar cells having SiH2Cl2 based I-layer materials

Intrinsic amorphous silicon films were fabricated using electron cyclotron resonance (ECR) assisted chemical vapor deposition and SiH2Cl2 source,gas. Intrinsic layers were used for material characterization and also for the a bsorber layer of solar cells, The highly reducing atmosphere produced by th e high energy ECR hydrogen plasma used to deposit these intrinsic films cau sed some degradation and/or etching of the previously deposited solar cell doped layers as well as the SnO2-coated glass substrates. The p-layer etchi ng rates were greater than those of the n-layer when these layers were expo sed to ECR hydrogen plasma. Optimum photovoltaic performance was achieved w hen an optimized n/i interfacial buffer layer was used for a solar cell dep osited in the n-i-p sequence. Better solar cell performances were obtained when the solar cells were measured under n-side illumination. In parr, the buffer layer optimization involved careful consideration of band gap matchi ng to the relatively wide band gap (1.85 eV) intrinsic layers prepared from SiH2Cl2. Further performance gains were possible through transparent condu ctive oxide/substrate optimization. For example: the open circuit voltage ( V-oc) increased to similar to 0.89 V when gallium-doped zinc oxide/glass su bstrates were used compared to similar to 0.63V when tin oxide/glass substr ates were used. Interface recombination and minority carrier diffusion leng ths were probed by n- and p-side illuminated quantum efficiency measurement and analysis. The electron and hole mu tau products were estimated to be 4 .4 x 10(-8) cm(2)/V and 3.5 x 10(-8) cm(2)/V, respectively. The stability o f the solar cells was also examined.