Ultrathin crystalline silicon solar cells on glass substrates

We fabricate thin crystalline silicon solar cells with a minority carrier diffusion length of 0.6 +/- 0.2 mu m by direct high-temperature chemical vapor deposition on glass substrates, This small diffusion length does not allow high cell efficiencies with conventional cell designs. We propose a new cell design that utilizes submicron thin silicon layers to compensate for low minority carrier diffusion lengths. According to theoretical modeling, our design exhibits excellent light trapping properties and allows for 10% efficiency at an optimum cell thickness of 0.4 mu m only. This submicron range of cell thicknesses was formerly thought to require direct band gap semiconductors. (C) 1997 American Institute of Physics.